Note: Descriptions are shown in the official language in which they were submitted.
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DIGITAL CORE WORKFLOW METHOD USING DIGITAL CORE
IMAGES
FIELD OF THE INVENTION
The present invention relates to methods for determining formation depths, and
more particularly to core logging methods.
BACKGROUND OF THE INVENTION
Although relatively expensive, coring - the taking of subsurface rock samples
with specialized drilling tools - is one of the oldest methods of subsurface
formation evaluation and the only method (other than cuttings analysis) for
providing rock samples for laboratory analysis. Coring is used to provide
geologists and other earth scientists with physical rock samples that can
provide
much-needed information on a direct rather than indirect basis.
A core bit is used to cut a generally cylindrical section of rock that is
contained
within a coring tube, which section within the tube is then brought to surface
(any
expected portion of the core that does not make it back to surface is
considered
to be "lost core"). The core tube is marked with a well name, core number, and
subsurface interval depths and orientation (which end of the core was
originally
up-hole) by workers on the drilling rig. The marked core tubes, which may need
to be frozen in the field (especially oil sands cores), are transported to a
core
handling lab where cores (with tube) are cut or "stabbed" along the tube
length
into two halves (see step 20 of Figure 2, which Figure summarizes the
traditional
physical core workflow), one side for viewing and the other side for cutting
physical samples. The stabbed two halves are placed in two separate sets of
boxes for future handling, with the viewing side being cleaned first before it
is
placed into core boxes. Core boxes of the two separate sets are labelled in a
certain way to preserve the field information of the cores, including the well
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name, core number and orientation. Additional information (e.g. physical core
box number) is added to the box label. If the cores are frozen, the sample
side of
the core will be sent back to a freezer to preserve the original state, and
the
viewing side of the core will be displayed in a room to be dried at step 21,
normally at room temperature and typically for 24 to 48 hours.
Various tests and analyses can then be conducted on the cores in a laboratory
setting. Traditionally, after the viewing side of the cores are dried to a
certain
degree, geologists use the physical core to engage in "core logging" at step
22
which includes determining core depths and core order in the subsurface and
describing the cores. Geologists also need to provide guidelines for lab
technicians to select, or select by themselves, sample intervals (at step 23)
and
then do physical samplings (at step 27) with digital image shooting (at step
24)
and image annotation (at step 25) in between.
Geologists need to determine exactly where (at what depths) the rock samples
were taken from in order to understand geology deep in the Earth and to assess
the spatial occurrence of mineral resources. As depth analysis is part of core
logging, core depth correction has also been routinely performed by geologists
for many years. During drilling, core depths are recorded by workers on a
drilling
rig, but very often they are not accurate (off-depth), and the geologist is
faced
with the task of attempting to determine depth information based on rock that
has
already been brought to surface.
The task of depth determination has been aided considerably by the
development and use of special tools (well logging tools) which measure
physical
rock properties around the borehole. These rock properties include rock gamma
radiation, resistivity, and porosity, among many others. Logging tools are
sent
downhole and take measurements at even spacing along the borehole. All the
measurements for a given rock property, when plotted out against depth, will
produce a rock property curve (or well log). Any given well will normally have
a
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suite of well logs, and the depths on well logs are believed to be generally
accurate if good logging procedures have been followed during well logging. As
can be seen, rock samples and well logs provide different kinds of information
from virtually the same object (rock), an analogy being the human body and its
X-
ray image. As a result, it is expected that a suite of well logs will match
the
physical cores in a certain way, which is the basis of core depth correction
with
well logging data as the depth reference.
Depth correction is used to shift initial core depths to match the depths
determined by well logging data (including well logs and borehole imaging
logs),
as the latter is considered to provide accurate depth information. In a
traditional
physical core workflow, geologists bring a paper copy of the relevant well
logs to
the lab and lay them out on a table side-by-side with the core boxes, along
with a
copy of the field core depth sheet. They will then locate a depth reference
marker on the well logs and its corresponding depth marker on the cores,
assigning the depth of the depth reference marker to the corresponding core
marker. Based on core length from the core depth reference marker and the
depth of the marker itself, geologists then calculate depths of any points on
the
cores above and below the marker. They repeat this process until all the cores
are depth-shifted or depth-corrected and have a good depth match with the well
logs. A corrected core depth table, which normally includes top and base
depths
of each core box (and lost core intervals if any exist), is produced and
provided
to the lab for calculating sample depths. They may need to adjust lost core
intervals (add or delete) and amend core orders to achieve a good match
between the cores and the well logs. A mismatch between cores and well logs is
normally caused by (1 ) core depths (including lost core intervals) being
incorrectly recorded in the fields, (2) core expansion, (3) core being upside-
down,
(4) core being misplaced, or (5) any combination of these four. Depth
correction
alone normally takes 3 to 4 hours for a typical oil sands well.
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Following core depth correction, geologists engage in core description by
looking
at physical cores (including visually estimating volume of shale), observing
and
describing the cores and recording a description on paper or in a computer
file.
Core description will normally take 4 to 8 hours per oil sands well. Core
depth
correction and description are normally performed by one geologist.
After the cores are described, the geologist will provide sampling guidelines
to
enable a lab technician to select the sample intervals (or mark sample
intervals
by themselves). A lab technician will select sample intervals on the viewing
portion of the cores, mark the sample intervals on the core boxes, and then
calculate the sample depths based on the corrected core depth table provided
by
the geologist. The lab technician will also need to determine the physical
position on the core for every meter depth, and these positions are marked on
the core boxes for later use. Determination of sample depths and meter depth
are traditionally achieved by using measurements of physical core lengths to
enable calculation based on core top/base depths in the corrected core depth
table. Sample selection/marking, sample depth calculation and
determination/marking of position for each meter depth normally takes 2 to 4
hours per oil sands well. The marked sample intervals will usually then be
translated to the sampling portion of the cores by another lab technician to
guide
physical sampling.
The viewing side of the core, which has been described by the geologist and
marked with sample intervals, is then transported to a digital lab for digital
imaging at step 24. Before digital images of the cores can be taken, the
photographer needs to manually place many labels onto the physical cores,
normally with magnetic stickers. There are three key label types (in addition
to
others): (1 ) top and base depths of cores; (2) sample intervals and sample
numbers; and (3) meter depths. The manual, hard-coded labelling is a very time-
consuming process and prone to errors; it also makes any updating of labels
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extremely difficult, especially when the geologist changes a depth. Changes in
the geologist's core depths normally require re-calculating of meter
depths/sample depths, which also requires "laying out" of the physical cores
again and probably re-shooting the digital images. Labelling and digital
imaging
typically take 3 to 4 hours per oil sands well. Any label updating or re-
shooting
will add extra time to this process. This process produces raw digital images
with
labels.
Raw digital images with labels need to be cropped, and other information such
as
well name, depth scale, and company logo will be added to produce ready-for-
print images at step 25 or 26. This process normally takes less than one hour
per oil sands well. Ready-for-print digital core images will then be printed
on
high-quality photographic paper to produce core photographs or on paper at
step
26. A paper copy is generally used by the lab technician to translate sample
intervals that are marked on view-side cores and recorded on the digital
images
to the sample-side cores to enable physical sampling. The core photograph hard
copies are normally not printed out on photographic paper until the passage of
1
to 4 weeks, to avoid any potential waste should any update on image annotation
be needed.
As is abundantly clear from the foregoing, there are numerous disadvantages to
the traditional physical core workflow:
1 ) Several people are necessarily involved. More than eight people (one
geologist and more than seven lab technicians) are usually involved, from
core stabbing to producing deliverable results for oil companies. The
more people that are involved, the harder it is to co-ordinate and the more
opportunities there are for mistakes. There are more inherent errors as
well.
2) The traditional workflow is time-consuming (as can be seen in Figure 2). It
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typically takes 24 to 48 hours to dry oil sands cores. Seventeen to twenty
two hours elapses from core logging (core depth correction and
description) to producing ready-for-print digital images and getting ready
for physical sampling, and another 1 to 4 weeks will usually pass while
waiting for the core photographs.
3) The reliance on a physical core workflow. Most processes are happening
on physical cores. People involved therefore need to be physically
present in a lab, working on the physical cores. The workflow also
accordingly requires usage of physical lab space.
4) Geologists do the depth correction and core togging with physical paper-
copy well logs and physical cores. In order for them to do core depth
correction, geologists need to visually estimate the depth of a depth
marker on well logs, and then manually translate that depth to the
corresponding core depth marker, to physically measure the core length at
a given point from a core marker with a measuring tape (and then to
calculate the corrected depth of the given point). They need to repeat the
above process for every point for which they need to calculate a corrected
core depth. The process is slow and prone to errors; in addition, any
change in the depth of a depth marker requires repetition of the above
steps.
5) The use of manual, hard-coded labelling. All sample intervals, core depth
and meter depth labels, plus all other labels are manually placed on the
physical cores before any digital images are taken. The labelling process
is time-consuming and prone to errors, and the resultant labelling (now
part of the images) is hard-coded and makes it extremely difficult to make
any required updates and changes.
6) Due to the time-consuming nature of the traditional workflow, sample
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selection and sample depth calculation are normally carried out by a lab
technician with sampling guidelines provided by a geologist. As a result,
sample selection is not totally controlled by the geologist, and very often
more samples are taken than is needed.
What is needed, therefore, is an improved and more efficient workflow that
overcomes the above disadvantages of the traditional physical workflow.
SUMMARY OF THE INVENTION
The present invention accordingly seeks to provide a method for utilising
digital
core images in depth registration and correction processes.
The present invention further seeks to provide a digital, integrated workflow
comprising a method for utilising digital core images in core depth
registration,
core depth correction, sample selection, digital image annotation, shale
volume
quantification, facies interpretation and core description.
According to a first aspect of the present invention there is provided a
method for
registration of downhole core depth information comprising the steps of:
a. providing at least one digital image of a core sample from a well;
b. displaying the at least one digital image on a display device;
c. selecting a displayed interval from the displayed at least one digital
image, the displayed interval being defined by a first depth and a
second depth spaced from the first depth;
d. establishing an approximate actual depth value for the first depth of
the displayed interval; and
e. measuring the length of the displayed interval to determine an
approximate actual depth value for the second depth of the
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displayed interval.
According to a second aspect of the present invention there is provided a
method
for registration and correction of downhole core depth information comprising
the
steps of:
a. providing at least one digital image of a core sample from a well;
b. providing well logging data corresponding to the core sample;
c. displaying the at least one digital image on a display device;
d. selecting a displayed interval from the displayed at least one digital
image, the displayed interval being defined by a first depth and a
second depth spaced from the first depth;
e. establishing an approximate actual depth value for the first depth of
the displayed interval;
f. measuring the length of the displayed interval to determine an
approximate actual depth value for the second depth of the
displayed interval;
g. displaying the well logging data adjacent the displayed interval;
h. allowing for comparison of the well logging data and the displayed
interval; and
i. allowing for correction of the first depth and the second depth.
According to a third aspect of the present invention there is provided a
method
for on-line registration and correction of downhole core depth information
comprising the steps of:
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a. providing a web portal for accessing digital images and well logging
data and a server for storing the digital images and the well logging
data;
b. allowing for uploading of at least one digital image of a core sample
from a well to the server;
c. allowing for uploading of well logging data from the well to the
server;
d. downloading and displaying the at least one digital image on a
display device;
e. selecting a displayed interval from the displayed at least one digital
image, the displayed interval being defined by a first depth and a
second depth spaced from the first depth;
f. establishing an approximate actual depth value for the first depth of
the displayed interval;
g. measuring the length of the displayed interval to determine an
approximate actual depth value for the second depth of the
displayed interval;
h. downloading and displaying the well logging data adjacent the
displayed interval;
i. allowing for comparison of the well logging data and the displayed
interval; and
j. allowing for correction of the first depth and the second depth.
According to a fourth aspect of the present invention, there is provided a
method
for determining shale volume in a core sample from a well comprising the steps
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of:
a. selecting at least one region of a digital image of the core sample to
represent a shale type;
b. specifying colour threshold values for the shale type;
c. specifying shale volume calculation options; and
d. calculating a shale volume value.
Preferably, a plurality of shale volume values are calculated, each at a
discrete
shale volume depth point, enabling plotting of a shale volume curve which can
be
displayed on a display device. This fourth aspect can be combined with the
methods of the first, second and third aspects of the present invention.
According to a fifth aspect of the present invention, there is provided a
method
for enabling facies interpretation of a core sample from a well comprising the
steps of:
a. displaying a digital image of the core sample on a display device;
b. defining at least one facies by means of characteristics including
facies colour and minimum and maximum shale volume value cut-
offs, the facies colour and minimum and maximum shale volume
value cut-offs being determined by reference to the digital image of
the core sample;
c. selecting a facies interval directly from the digital image by
selecting first and second locations representing top and base
depths of the facies interval;
d. identifying the at least one facies with at least a part of the facies
interval based on the characteristics;
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e. displaying the at least one facies on the display device according to
the top and base depths; and
f. allowing for inspection and interpretation of the displayed at least
one facies.
This fifth aspect can be combined with the methods of the first, second, third
and
fourth aspects of the present invention.
According to a sixth aspect of the present invention, there is provided a
computer
readable memory having recorded thereon statements and instructions for
execution by a computer to carry out the method of any one of the other
aspects
of the present invention.
According to a seventh aspect of the present invention, there is provided a
digital
core workflow method comprising the steps of:
a. providing at least one digital image of a core sample from a well;
b. providing well logging data corresponding to the core sample;
c. displaying the at least one digital image on a display device;
d. selecting a displayed interval from the displayed at least one digital
image, the displayed interval being defined by a first depth and a
second depth spaced from the first depth;
e. establishing an approximate actual depth value for the first depth of
the displayed interval;
f. measuring the length of the displayed interval to determine an
approximate actual depth value for the second depth of the
displayed interval;
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g. displaying the well logging data adjacent to the displayed interval;
h. allowing for comparison of the well logging data and the displayed
interval to enable selecting corresponding depth markers on the
displayed interval and the displayed well logging data, and to
enable adjusting lost core intervals;
i. allowing for correction of the first depth and the second depth;
j. selecting at least one region of the at least one digital image of the
core sample to represent a shale type;
k. specifying colour threshold values for the shale type;
I. specifying shale volume calculation options;
m. calculating a shale volume value;
n. defining at least one facies by means of characteristics including
facies colour and minimum and maximum shale volume value cut-
offs, the facies colour and minimum and maximum shale volume
value cut-offs being determined by reference to the at least one
digital image;
o. selecting a facies interval directly from the at least one digital image
by selecting first and second locations representing top and base
depths of the facies interval;
p. identifying the at least one facies with at least a part of the facies
interval based on the characteristics;
q. displaying the at least one facies on the display device according to
the top and base depths;
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r. allowing for inspection and interpretation of the displayed at least
one facies; and
s. using corrected top and base depths to annotate the at least one
digital image.
In exemplary embodiments of the present invention, the providing of the well
logging data and the at least one digital image of a core sample from a well
is
achieved by obtaining the well logging data and the at least one digital image
from an oil company. The display device is preferably a computer monitor
receiving signals from a user computer workstation.
The displayed interval is preferably selected by means of: positioning a mouse
cursor over a first location on the displayed at least one digital image
representing the first depth; clicking a mouse button to select the first
location;
positioning the mouse cursor over a second location on the displayed at least
one digital image representing the second depth; and clicking the mouse button
to select the second location. The first depth may represent either the top
depth
of the displayed interval (with the second depth then representing the bottom
depth of the displayed interval) or the bottom depth (the second depth then
representing the top depth). The approximate actual depth value for the first
depth is preferably established based on field data, as explained below, and
the
length of the displayed interval is preferably measured by means of a
predetermined digital ruler that equates pixel numbers with a set length
value.
After depth registration is accomplished, comparison and correction processes
can be conducted. Preferably, the step of allowing for comparison of the well
logging data and the displayed interval is achieved by means of displaying the
well logging data and the displayed interval in parallel, adjacent
orientation,
enabling a user to visually inspect the well logging data and the displayed
interval
for correlation purposes. Allowing for correction of the first and second
depths is
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then preferably achieved by means of: allowing a user to pick corresponding
markers on the well logging data and the displayed interval, by means of mouse
cursor positioning and location selection; inserting correlation lines
connecting
the corresponding markers; inspecting the digital interval to determine if
there are
any lost core intervals; adding any desired sub-intervals to the displayed
interval
to represent lost core intervals; and axially shifting the displayed interval
such
that the correlation lines are generally horizontal. Preferred embodiment of
the
present invention comprise the further step of using corrected top and base
depths to annotate the at least one digital image.
The use of digital core images during depth registration, rather than reliance
on
the presence of physical core samples, provides tremendous advantages for
geologists and the companies they work for, particularly when this is linked
to the
use of the Internet for access and dissemination of information. While digital
images have been used in the past to summarize core logging information, and
occasionally for comparison against well logging data during depth correction
processes, the advantage of using digital core images in depth registration is
a
novel development in the field.
A method according to the present invention requires fewer personnel, with
time
expenditure reduced substantially when compared with traditional methods. All
information, including well logs and cores, is provided in digital form and
can
therefore be easily manipulated, analyzed, and distributed to others. The
geologist need no longer be confined to a laboratory setting to engage in core
logging, but can instead be at some remote location anywhere in the world at a
computer workstation.
Further, geologists engaged in traditional workflow can only do depth
correction
one box at a time, without having ready access to the whole picture of the
entire
well. The present invention, by contrast, can display both well logs and core
images for the entire well on one screen by changing depth scale, and depth
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correction can be performed at the same time for the entire well. The methods
of
the present invention allow a user to attempt different correlation and
matching
scenarios before proceeding to the depth correction stage, and a user can
easily
insert or delete lost core or adjust core order.
In the end, the present invention can produce highly accurate depth
determinations, integrating depth registration/correction with sample picking,
image annotation, VSH (shale volume) calculation and picking facies intervals
directly from digital core images, streamlining the entire core workflow.
A detailed description of an exemplary embodiment of the present invention is
given in the following. It is to be understood, however, that the invention is
not to
be construed as limited to this embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary embodiment of the
present invention:
Figure 1 is a schematic illustration of a digital core workflow according to
the
present invention;
Figure 2 is a schematic illustration of a traditional physical core workflow;
Figure 3 is a schematic illustration of a system for executing a method
according
to the present invention;
Figure 4 is a schematic illustration of the modules and information flow of
the
present invention;
Figure 5 is a flowchart illustrating a method according to the present
invention;
Figure 6 is a representation of a login window;
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Figure 7 is a representation of a project name entry window;
Figure 8 is a representation of a well name entry window;
Figure 9 is a flowchart illustrating the depth registration process;
Figure 10 is a screen shot of a digital ruler definition window;
Figure 11 is a representation of a raw digital core image with core number and
box number as the only labels;
Figure 12 is a screen shot of a Smart DepthsT"" window illustrating how
various
depth registration information is displayed on an annotated core image;
Figure 13 is a screen shot of a well log loading window;
Figure 14 is a flowchart illustrating the depth correction process;
Figure 15 is a schematic illustration of the adjacent display of well logging
data
and stacked core images during the marker-picking portion of the depth
correction process;
Figure 16 is a schematic illustration of the adjacent display of well logging
data
and stacked core images during the fine-tuning portion of the depth correction
process;
Figure 17 is a screen shot of the display during the fine-tuning portion of
the
depth correction process;
Figure 18 is a lost core deletion window;
Figure 19 is a lost core insertion window;
Figure 20 is a screen shot illustrating uncorrected and corrected depths on a
display;
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Figure 21 is a raw digital image with annotations;
Figure 22 is a raw digital image provided with a frame and associated
information;
Figure 23 is a digital core image with full annotation and frame information;
Figure 24 is a screen shot of a digital core image after selection of two
sample
intervals;
Figure 25 is a sample registration window;
Figure 26 is a representation of a sand/shale calibration window for shale
volume calculations;
Figure 27 is a shale volume calculation options window;
Figure 28 is a screen shot of one embodiment of a display in the Depth
Correction Window;
Figure 29 is a screen shot of a facies definition window; and
Figure 30 is a flowchart illustrating the facies interpretation process.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
A preferred embodiment of the present invention will now be described with
reference to the accompanying drawings. The preferred embodiment of the
present invention will be described below by reference to an overall digital
core
workflow, which digital core workflow comprises a method and system referred
to
as ADFMT"~ (an acronym for "Accurate Depths for Facies and Modeling").
Digital Core Workflow
Referring now in detail to Figure 1, a digital core workflow is illustrated in
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accordance with the present invention. As can be seen, after cores (which may
be frozen) are stabbed into two halves at step 1, the view-side cores are
placed
at step 2a into a specialized drying room 2b for approximately 10 to 14 hours
to
dry the cores, instead of simply displaying the cores in an ordinary core-view
room. The specialized drying room 2b is tightly sealed after the doors are
closed
and is separated from other ordinary view rooms or office rooms. The
temperature in the room is settable, and is normally higher than room
temperature. The humidity is settable, as well, through dehumidifiers, at a
level
normally much lower than typical office conditions. The room 2b is also
provided
with good internal circulation. The composite effect of the above three
conditions
is that the cores can be dried much faster, reducing drying time from 24 to 48
hours down to 10 to 14 hours for typical oil sands cores.
Dried cores are then transported to a digital imaging studio for digital
imaging at
step 3. This workflow order is very different from the traditional physical
core
workflow in which this step 3 happens near the end of the workflow process
(see
step 24 in Figure 2). This change in workflow order allows for a prompt
acquisition of the digital format data of the cores, to enable the depth
registration
process (described below) to begin. Only the core number and physical box
number are required to be placed onto the physical cores for labelling, since
any
other labels can be added digitally with the ADFM system at step 4. This
simplified labelling requirement can reduce digital core image shooting time
from
3 to 4 hours per oil sands well to less than one hour.
All processes at step 4 take place digitally in the ADFM system, and the view-
side cores can be sent at step 6 to a core storage facility. The ADFM system,
described in detail below, is a computer-assisted system that enables the use
of
digital core images in the core logging work that is normally done by
geologists
and some of the work traditionally done by lab technicians. As will be clear
from
the following description, this integrated digital ADFM system overcomes the
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disadvantages of the traditional physical workflow described above. The
preferred embodiment of the ADFM system comprises the following seven
functionalities:
1 ) Displaying digital well logging data such as digital well logs, micro-
s formation imaging, etc. for use as a depth reference;
2) Registering (assigning) core depths on raw digital images;
3) Performing core depth correction using digital well logging data and
digital
core images;
4) Selecting samples on digital core images;
5) Calculating sample depths;
6) Annotating raw digital core images with desired labels and generating
composite digital images that combine raw digital core images with
annotation for core photograph hardcopy printing (annotations may
include sample intervals and sample numbers, core top/base depths,
meter depths, well name, company name, company logo, depth scale bar,
plus other labels);
7) Calculating volume of shale directly from digital core images;
8) Functionalities for enabling geologists to record their core descriptions
and
export the results, including facies (rock groups) determinations; and
9) Exporting results.
The ADFM system preferably produces the following five sets of results:
1 ) Corrected core depths, with lost core interval depths, for core box
labelling;
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2) A sample list with corrected core depths, NA (Not Analyzed) intervals and
lost core intervals;
3) Annotated digital core images that are ready for hardcopy print on
photographic paper (annotated images are also provided by paper copy to
the lab to assist in physical sampling on sample-side cores, according to
sample intervals annotated on the images);
4) VSH and facies results; and
5) Selected content of the Depth Correction Window.
One implementation of the preferred embodiment of the ADFM system has
demonstrated that the ADFM system can reduce the time from the digital imaging
stage to the physical sampling stage from 17 to 22 hours per oil sands well to
approximately 3 to 5 hours. It can also reduce the number of required
personnel
from five people (as required in the traditional workflow) to two people (in
the
ADFM system - one photographer for digital imaging and one geologist for
operating the ADFM system). With ADFM, more accurate core depths and
sample depths can be produced. A core photo hardcopy can be printed out on
photographic paper immediately upon completion of the desired processing and
delivered to the oil company within 1 to 2 days, since core depth correction,
sample selection and image annotation are handled by one geologist in a very
efficient and consistent way. This is in contrast to the traditional physical
core
workflow where one might wait 1 to 4 weeks before digital image printing,
since
information for annotation is obtained from different sources: (1 ) core
depths are
provided by a geologist, (2) meter depths and sample intervals are provided by
a
lab technician, (3) most labels are put on by a photographer, and (4) the
remaining labels such as company name, well name, etc. are added by an image
editor.
ADFM System
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Referring now in detail to Figure 3, an ADFM system according to the present
invention is illustrated for executing a method according to the present
invention.
As can be seen, an ADFM user 31, with access to the ADFM system 32, is
connected through the Internet 33 to a data server 34 to retrieve their
assigned
privileges from the data server 34, as described in detail below. The user 31
is
provided with digital images and well logging data either through the Internet
connection or by means of portable storage media 35. The clients 36 (oil
companies, labs, etc.) provide raw data to users by uploading raw data to the
data server (by browser or ftp client 37) or through portable storage media
35,
the users 31 typically being geologists or other earth science professionals
employed by the oil company 36 as full-time or contract workers to analyse the
raw data from the clients 36 and then upload analyzed results to the data
server
34. The users 31 can also deliver results (for example, back to the oil
company
36) through portable media 35 or paper copy. Clients 36 or any authorized
users
can browse or download results from the data server 34. When raw data is
provided in a digital format (digital core images and digital well logging
data) and
results are delivered in a digital format, ADFM users 31 can accordingly
remotely
perform core logging work without ever looking at any physical cores in a
traditional lab, and can provide their services to different clients globally,
which is
logistically extremely difficult to achieve in the traditional physical core
workflow.
The preferred embodiment of a method according to the present invention
comprises a series of stages, namely Program Initiation, Depth Registration,
Depth Correction, Annotation, Finalizing Annotated Images, Sample Selection,
VsH (shale volume) Calculation, Facies Interpretation, and Result Export
(including Depth Correction Window Export). These stages each have their own
corresponding module, as is illustrated in detail in Figure 4, and will each
be
addressed in detail in the following, with reference to the accompanying
drawings.
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PROGRAM INITIATION
Referring now in detail to Figure 5, Program Initiation begins when the
program is
accessed by a user. As the preferred embodiment is web-based, the user would
utilise an Internet connection to log onto the server to obtain the assigned
privileges from the data server. The user will be presented at step 50 with a
window (see Figure 6) that enables entering a username and password, which
username and password will have been set up and stored in the data server
before the user requires access to the ADFM program. The preferred user
verification process is of a commonly employed form. When the user enters
their
username and password at step 50, the program will connect to the database
server to retrieve pre-assigned access privileges at step 51 using the
username
and password. If the combination of the username and password exists in the
data server, the program will enable or disable certain modules (see Figure 4)
of
the ADFM system based on the retrieved access privileges. If, for example, the
retrieved value for a module is 1, the module is enabled; if the retrieved
value for
a module is 0, the module is disabled.
Once user verification is accomplished and the user has been provided access
to
the full program functionality, the next step is to create a "project" at step
52. To
do this, the user enters a project name in an input window (such as that shown
in
Figure 7); the project name then becomes the name of a folder on the hard
disk.
The user is preferably given a number of options after the new project is
created:
a) Open a project, which enables the user to select a project folder
and set it as a working project;
b) Save, where information is saved;
c) Save as, to save a project under a new name; and
d) Exit, to quit the program.
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The next step 53 is to add the name of a well (one well at a time) to a
working
project, thereby creating a placeholder. The user can add as many wells to a
project as desired. Where a number of wells are added, a well list will be
generated and saved for access by the user in selecting a "working" well for
the
given project. The user will be presented with options regarding wells:
a) Add, to add a well to the current project; a well name is provided by
the user (as shown in Figure 8); when a well is added, a folder with
that well name is created;
b) Export, to save well information of the selected wells) from the
current project into a file;
c) Import, to import well information from a file created in Export from
another existing project;
d) Delete, where the well list is displayed for the user to select a well
to delete; and
e) Select, where a well can be selected from the well list under the
current project as the working well.
After a well is added to a project, the next stage, then, is for the user to
load
digital core images at step 54, the raw digital images being previously
received
from an oil company. The raw digital core images can be loaded from portable
storage media or downloaded from the data sever (see Figure 3), depending on
how the raw data was provided by the client. A well is usually represented by
15
to 25 images in any image format, which images are presented in file list form
in
a typical file-open window and can be loaded one-by-one or all at once. The
user will again be presented with options:
a) Load, to load images into the current well; a "file open" window is
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presented to enable the user to browse and select images to load;
b) Select, to select an image from the image list of the current well as
the working image and display it in the Depth Registration Window
(discussed below); on the list, images that have been depth-
s registered are separated from the rest with a special sign or
marker; and
c) Delete, to delete selected images (one or more) from the well.
In the Depth Registration Window (illustrated in Figure 12 and discussed in
detail
below), the selected image can be zoomed in, zoomed out, or rotated 90°
left or
right. Three special zoom functions are also available: 1:1, Fit-all, and Fit-
width,
the default being Fit-all. Four image navigation buttons are also provided:
First,
Previous, Next, and Last. The Depth Registration Window is a workspace on the
screen for use in engaging in steps related to the raw digital core images.
Three
modules (see Figure 4) are associated with the Depth Registration Window: (1 )
the Depth/sample Registration Module for registering core depths and selecting
sample intervals; (2) the Facies Registration Module for selecting facies
top/base
depths; and (3) the Annotation Module for adding, displaying, and manipulating
annotation.
Once the raw image has been selected at step 55, the program will then display
the core image in the Depth Registration Window (as shown in Figure 11 ),
labelled only by core number and box number; note that the core number defines
a discrete section, or "run", of core (usually 3m in length for oil sands
cores),
while the box number identifies the box where the actual physical cores are
stored. While digital image providers normally must spend a substantial amount
of time providing detailed annotation before shooting digital images, the
limited
annotation requirements of the present invention enable a relatively rapid
shooting of digital core images, cutting down considerably on their
acquisition
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time. Traditional core labs will normally have to manually insert information,
such
as by putting magnetic stickers of sample intervals, sample numbers, core
top/base depths, core meter depths, etc., on a metallic framing structure to
label
cores, before taking any digital photographs, and hence there is a substantial
time savings in a method according to the present invention, normally reducing
the required time from 3 to 4 hours per oil sands well to less than one hour.
DEPTH REGISTRATION
The next stage of the ADFM process is Depth Registration (step 56 of Figure
5).
A flowchart illustrating the steps of the depth registration stage is
presented in
Figure 9, which steps are explained in greater detail below.
First, the user must select an image at step 91 to display it in the Depth
Registration Window and then define a "digital ruler" at step 92, which
digital
ruler will be employed by the program to determine an exact, actual length of
the
interval in question. To define the digital ruler, the user right-clicks
(using the
mouse) anywhere over the displayed image to display a pop-up menu and then
selects "Define digital ruler" from the menu. The user clicks on any two
points on
the displayed image and a "Define digital ruler" window is popped up (see
Figure
10), including the horizontal distance on the digital image in term of pixels
between the clicked two points (2389 pixels in Figure 10), and two radio
buttons
for selection (one for 0.75m and the other for an alternative length defined
in the
user-input box). When the OK button is clicked, the window closes, which
establishes a user-defined relationship between digital image sizes in terms
of
pixels and physical core lengths in terms of meter. For example, if the 0.75m
radio button is selected, the program defines a digital ruler in which 2389
pixels
on the image are equivalent to 0.75m of physical core length. This
relationship
will be maintained and used to calculate core length during the core depth
registration process until a new digital ruler is established.
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Once the digital ruler is defined, depth registration proceeds by means of the
Smart Depths process, details of which process follow with reference to Figure
12.
According to the Smart Depths process, the user will select top and base depth
points using the mouse to define a desired interval, and there can be multiple
selected intervals within the same digital image. The user selects the top and
base depth points by clicking at two locations on the image itself at step 93.
The
program then measures and crops a rectangular area (a depth registration
rectangle) between these top and base depth points for later use and pops up a
Smart Depths window at step 94 for the user to input/confirm depth
registration
information for the interval defined by the depth registration rectangle.
Depth
registration information includes core identification (core number, box number
and interval number) and both top and base depths.
Core identification is then assigned in the following manner: the user will
manually input a core number in the Smart Depths window, and the program will
then automatically determine the proper box number. For example, using
common digital images where a typical core is 3m, there are two physical core
boxes (representing 1.5m of physical core each). The first physical core box
has
the number "1" as its box number and the second physical core box has the
number "2" as its box number. Each 1.5m core box will result in two 0.75m
image sections, which are labelled "A" and "B", respectively. As a result,
core
box identification will have a format such as 1A, 1 B, 2A, 2B, etc., where "1"
and
"2" provide the physical core box sequence and "A" and "B" represent the first
and second 0.75m core within a physical core box. The program automatically
advances the box number from 1 A to 1 B, 2A, 2B, 3A, etc., when one Smart
Depths window is completed and the user proceeds to define the next adjacent
displayed interval (a new Smart Depths window is employed for each subsequent
selected interval). This automatic advance in box number can be altered by the
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user if desired at step 95.
For the first Smart Depths window representing the most shallow core interval,
the user will manually input the top depth, which will normally be determined
in
the field by coring personnel, and the program will then automatically
determine
the base depth based on the digital ruler and the distance on the image
between
the two clicks. The base depth will be remembered by the program and used as
the top depth for the next adjacent descending core interval (the last depth
from
the former Smart Depths window cannot be changed by the user within the new
Smart Depths window, but the user can amend the top depth in the new Smart
Depths window at step 95).
When moving on to the next core, the user will manually input a new core
number in the Smart Depths window, otherwise the program will assume that the
user is still working with the previous core interval and only update the box
number. The program will then automatically reset the box number to 1A and
calculate the new interval length and the base depth; the interval number is
specified by the user and remains the same until it is changed again. After
the
user makes necessary changes at step 95, the user will be presented with the
option of either accepting the edit at step 96a or cancelling the edit at step
96b.
If "Accept" is chosen, the program will crop out the rectangular portion, save
it
with its core identification and top/base depths at step 97, and automatically
annotate each registered interval with the core number, box number, interval
number, and top and base depths, in a program-defined format (as shown in
Figure 12).
The user can repeat steps 93 through 97 until all core intervals on the image
are
depth-registered. The user then moves to the next image to do depth
registration
at step 98.
Although the preceding has been presented as a top-down registration process,
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registration can be conducted top-to-bottom or bottom-to-top, at the option of
the
user. The program automatically determines whether registration is being
conducted top-to-bottom or bottom-to-top, based on the relative positions of
the
two mouse-selected points and their order of selection. If the user changes
registration direction during the process, however, the user will need to
ensure
that the depths are being accurately determined, and the user may need to
manually amend the core/box/interval number if necessary when the first Smart
Depths window is popped up after a change of depth registration direction.
Depth consistency is also checked by the program, such that shallower depth
images cannot be overlapped with or displayed as being deeper than any deeper
images.
Having completed the initial depth registration steps, the registration
information
can be modified by the user at this stage. If the user clicks anywhere within
a
selected depth registration rectangle, the depth registration window is popped-
up
with the associated information, including top/base depths and core length.
The
user can also change the core/box/interval number. However, any change in one
depth registration rectangle will not trigger changes in other depth
registration
rectangles, so the user will need to revise other interval information as
desired.
The user can also delete registration information by entering depth deletion
mode, which enables deletion of a selected piece of information or all depth
registration information for the core image, and start again.
Once the user has completed all depth registration for the digital core
images,
the user can then close the core image window and proceed to core Depth
Correction in the Depth Correction Window. Optionally, the user can select and
register sample intervals, as well, at step 57 of Figure 5. Sample selection
will be
described in detail below.
DEPTH CORRECTION
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The Depth Correction Window is the workspace on the display wherein the user
performs all actions related to stacked images that are cropped from raw
digital
core images, which cropped images were defined by depth registration
rectangles during the depth registration process in the Depth Registration
Window.
After core depth registration is completed for all raw digital core images,
the user
will then load corresponding well logging data at step 58 (which provides
depth
reference, so the well logs are sometimes termed "depth reference logs"),
enabling correcting of the core depths at step 59 below. The well logging data
can include GR, porosity, resistivity, dipmeter logs and/or high-resolution
borehole image logs such as formation micro-imaging (FMI) logs. Well logging
data can be provided in an oil industry standard format such as LAS or a
digital
image format (such as .tif or .jpeg) by oil companies, as was the case with
the
digital core images, and the user accesses the well logging data by means of
the
well logging data selection window shown in Figure 13.
As is shown in Figure 17 and described in greater detail below, the program
then
displays in the Depth Correction Window (1 ) the stacked, cropped core images
(that have just been registered) in a vertical orientation (the images
possibly
being highly compressed depending on the depth scale used), (2) the
corresponding core identification, and (3) the well logging data. All of these
three
pieces of information are displayed according to depths, and the depth scales
in
the Depth Correction Window can be changed by the user. In this preferred
embodiment, there will be two vertical core image stacks, one displaying the
cropped images according to their registered depths and the other displaying
the
cropped images according to either their registered depths or corrected depths
at
the user's option. The second stack is used in the depth correction process
detailed below (and illustrated in Figure 15). Any lost core intervals (depth
gaps
between any neighbouring cropped images) are filled with a highlight colour,
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such as red.
With depth reference well logs, stacked core images and corresponding core
identification displayed side-by-side on the display device, the user begins
the
stage of core Depth Correction (step 59 of Figure 5). Depth correction is to
recalculate the top/base depths of each cropped image based on depth markers
selected by the user and save the results for further analysis.
The first step in the depth correction stage is to pick depth reference
markers,
which is illustrated in the flowchart of Figure 14. Depth reference markers
will
usually be selected on the basis of some visible feature of importance, such
as a
lithology change; they are special contacts that can be easily identified on
both
well logs and core images by geologists. The user will select the marker-
picking
icon or a marker-picking menu to enter the marker-picking mode at step 141, in
a
manner well known to those skilled in the art. The user can then manually pick
corresponding markers on the well log and the digital image at step 142, said
depth markers being "picked" by clicking the mouse when the cursor is over the
desired point on the well logs and then the core images.
As is shown in schematic form in Figure 15, once corresponding markers are
selected, the program will insert horizontal lines 151 and 152 through each of
the
well logs and the core images, respectively, and then also insert a
correlation line
153 connecting those two horizontal lines. As many markers as are desired may
be selected. The user can delete markers, as well, either a single selected
marker or all markers.
Given the highly-compressed nature of the displayed images, there may be some
error where the user has been relying on their own visual inspection of the
displayed images to conduct marker-picking. The next step 143, therefore, is
for
the user to fine-tune the markers - to position a marker to an exact position
at
the user's choice. The user enters the fine-tune markers mode by selecting a
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fine-tune markers icon or fine-tune markers menu, which will pop-up a floating
window (which is shown in schematic form in Figure 16 and in a screen shot in
Figure 17). The floating window (fine-tune marker window) displays a drop-down
list 161 of all the markers that have been picked and a zoom-in 162 of a small
section of the digital image centring around the current active marker 163.
The
active marker 163 is the same one displayed in both the floating window and
the
stacked core images in the Depth Correction Window. The user can set a
marker as active, in the fine-tune markers mode, by (1 ) double-clicking a
marker
in the Depth Correction Window or (2) selecting a marker on the drop-down
marker list under the zoom-in 162 in the fine-tune markers window. When the
position of an active marker 163 is changed, the zoom-in 162 image will be
updated accordingly, and the new active marker 163 is highlighted in the Depth
Correction Window with a highlight colour defined in the program.
In addition to the pop-up of a floating fine-tune markers window, entering
fine-
tune marker mode will display the difference 164 in thickness (the thickness
being between any two adjacent markers) of a corresponding well log and
stacked core section in the Depth Correction Window. The preferred thickness
difference unit is centimetres (e.g. the thickness difference 164 is 20cm in
Figure
16). When the thickness difference exceeds a certain established value
(threshold value), the thickness difference is highlighted with a highlight
colour as
defined in the program to indicate a substantial thickness difference that the
user
may wish to examine in detail.
With the help of a floating window, the user then has a more magnified display
of
the digital image immediately surrounding the selected marker, and the mouse
is
then employed to drag the marker line 163 into a more desirable position based
on the magnified visual inspection. The active marker 163 can also be dragged
in the Depth Correction Window itself, and dragging in either window
automatically updates the marker in the other (and the thickness difference is
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CA 02516872 2005-08-23
updated accordingly).
After all markers are fine-tuned and moved to their correct positions on both
core
images and well logs, the thickness difference between any two neighbouring
markers should preferably be zero or close to zero, since the markers for any
corresponding well log and core image are intended to refer to the same
contact
in the subsurface. If the thickness is not zero, the geologist must decide,
based
on their professional knowledge and experience, what may have caused this
difference and take actions accordingly to render the thickness difference
zero.
There are three key potential causes for the geologist to consider: (1 ) lost
core
intervals have been recorded incorrectly in the field; (2) cores have been
misplaced or are upside-down; and (3) core expansion. Any one of these, or any
combination thereof, can cause a non-zero thickness difference.
Lost core adjustment takes place at step 145. If there is a lost core interval
which is too thick (when compared by the program to the well logging data),
which can be indicated by a sign in front of the thickness difference value
(e.g. a
"-" sign), the user places the mouse over the lost core interval and right-
clicks the
mouse to select the "Delete lost core" menu. A Lost Core Deletion window is
popped up (as is shown in Figure 18), showing the maximum lost core thickness
that can be deleted and an input box for the user to specify the lost core
thickness for deletion. The maximum thickness is the total thickness of the
lost
core interval at this position. When the "OK" button is clicked, the specified
lost
core thickness is deleted and all of the top/base depths of all cropped images
below the lost core interval are shifted up by the specified (deleted)
thickness.
A lost core interval can also be inserted into any join between two
neighbouring
cropped images. To do this, the user will place the mouse over a desired join
and right-click the mouse to select the Insert Lost Core menu, and a Lost Core
Insertion window is then popped up (as is shown in Figure 19), with an input
box
provided for the user to specify a lost core thickness to be inserted at the
join.
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When the "OK" button is clicked, the specified lost core interval is inserted
into
the join. If a lost core interval exists, the specified (inserted) lost core
interval is
added to the existing interval. The program will then shift down the depths of
all
cropped images below the insertion join by the specified (inserted) thickness.
The displayed core intervals (cropped core images) can each be moved
interactively up and down (if inaccurate vertical positioning is determined to
have
occurred) at step 144 or rotated 180° (if it is determined that core
was
accidentally placed upside down, either in the field or during image
shooting), if
there is an error clear from visual inspection of the well logging data and
digital
images. When a cropped image is moved from one place to another, a void (_
lost core) is left at the old position; a prompt is provided as to whether to
delete
the void or not. The depth of all markers and cropped images below the old or
new position, whichever is shallower, may need to be adjusted.
Core expansion is handled by the program automatically by shrinking cropped
image lengths to their corresponding lengths at the subsurface.
After lost core interval adjustment 145 and core order restoration 144, depth
correction of the stacked core images on the Depth Correction Window can be
performed. The user selects a depth correction icon or menu, whereupon the
program displays a table showing raw top/base depths and corrected raw/base
depths for all core boxes or cropped images, plus their thickness before and
after
depth correction, for the user to review. The positions of all of the markers
are
displayed, as well. "OK" and "Cancel" buttons are provided on the table for
the
user to confirm or cancel the action of depth correction. If the "OK" button
is
clicked, the program then automatically performs depth correction at step 147,
which calculates corrected top/base depths of all cropped images and adjusts
core expansion (if any exists), resulting in a display as shown in Figure 20.
Corrected top/base depths for all cropped images can be "locked" and remain
stable unless they are overwritten by the user by "locking again". As can be
seen
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in Figure 20, two stacked core image columns are presented, the first
representing the uncorrected depths and the second being updated so that all
cropped images are displayed according to their corrected top and base depths.
All markers picked on the core images will be aligned by the program at the
same level as their corresponding markers picked on the depth reference logs,
such that the two horizontal lines 151, 152 and the correlation line 153
connecting the two horizontal lines 151, 152 will then appear as one
horizontal
line. Note that the second column of cropped images need not provide the
corrected depth information; in other words, the first and second columns may
instead be presented in identical form (if it is desired, for example, to have
two
separate users each correct the uncorrected information for comparison
purposes).
Any given top or base will have two associated depths: a Raw Depth that was
assigned during depth registration, and a Corrected Depth that was calculated
when depth correction was performed. In addition, there is a Current Depth,
which is a working copy of top and base depths of cropped images. Before
depth correction is performed, Corrected Depth = Raw Depth. When displaying
the depth information, the program will offer the user with options as to
whether
to use Raw Depths or Corrected Depths.
Once correction is completed, the corrected information can be exported as
displayed or in text/table format at step 148 (part of step 60 of Figure 5).
Corrected cropped image top/base depths are used to calculate core top and
bottom depths, and meter depths. Core top/bottom depths and meter depths are
used for annotating raw digital core images, as described in detail below.
The depth correction process traditionally takes three to four hours for a
typical
oil sands core length, but this time is cut to less than one hour with the
ADFM
method according to the present invention.
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ANNOTATION
After correction of the registered depths, the user can proceed to annotate
the
digital images at step 61. As stated above, annotation has traditionally been
conducted by placing magnetic stickers on a metallic framing structure on the
core box, before any digital images are even taken. With the ADFM process, the
use of digital images as early as initial depth registration means that all
corrected
depth information is easily accessible and can be presented directly on the
digital
images themselves.
To begin, the user activates the Annotation Module in the Depth Registration
Window by clicking an annotation icon or by selecting an annotation menu, and
the program automatically transfers the corrected core top and base depths and
annotates them on the digital images; the program will also automatically
calculate the position for every meter depth and mark the position with a mark
and display the depth value adjacent the calculated position. This can be seen
in
Figure 21. If samples are selected, as described in detail below, the program
will
automatically annotate sample labels, sample numbers, and sample start and
end marks such as arrows. If lab analysis results from any samples are
available, an option can be turned on to display lab results adjacent their
corresponding sample labels. If facies have been interpreted, as described in
detail below, facies identification indicators can be annotated on the digital
image
with a corresponding facies colour.
Annotations displayed on core images by the Annotation Module can be moved
by click-and-drag of the mouse, to assist the user in ensuring that the
digital
images are not obscured by the labelling.
FINALIZING ANNOTATED IMAGE
Once the raw digital core images have been annotated at step 61, the user can
finalize the annotated images at step 62. To finalize the annotated images,
the
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CA 02516872 2005-08-23
program can add a frame, company name, well name, the digital ruler, the
client's company logo, etc. Any of this information can be included or
excluded at
the user's choice. Figures 22 and 23 illustrate the type of information that
may
be included when finalizing the annotated image. A final, printable copy of
the
annotated image, in the user's choice of digital image format, is then
generated
automatically by the program at step 63. The user may then print off the
finalized
annotated image at this stage or deliver it to the client by portable media or
uploading to the data server (for the client to download or browse through the
Internet).
SAMPLE SELECTION
A large number of rock samples are routinely taken from oil sands cores for
analyzing bitumen weight percentage in order to determine the richness of
bitumen. Sample intervals are selected on view-side cores by a lab technician
and marked on the core boxes. The digital photographer traditionally positions
sample labels according to these marks before shooting the digital core
images.
The digital images with sample sticker labels are then used to translate
sample
intervals to frozen sample-side cores to enable physical sampling. This
traditional sample selection/translation approach usually involves two people,
and is time-consuming and prone to errors.
To sample according to the preferred embodiment of the present invention at
step 57, the user selects a Sample Registration menu or clicks on a Sample
Registration icon to enter the sample selection mode. In the sample selection
mode, the user selects a sample interval by clicking on two points on the
digital
core image. The two points have to be within a depth registration rectangle so
that sample depths can be calculated based on the positions of the two points
related to core depths. After the two clicks are completed, a Sample
Registration
window is popped up (as shown in Figure 25) asking for three inputs from the
user: (1 ) Label (which indicates the kind of sample with a suggested value
that
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will remain the same unless the user makes a change to it); (2) Number (the
sequence number for the same kind of sample, which automatically increases by
one after every successful sample registration; the value will be re-set to
"1"
when the Label input box is changed by the user, and the value can be
overwritten by the user); and (3) two radio buttons for "Yes" and "No" to
indicate
if the sample number is to be displayed in the sample annotation ("Yes"
indicates
real samples and the sample information will be annotated on digital images;
"No" is for "false" samples and is only for text annotation where only the
Label
value will be annotated on digital images). After "OK" is selected, the sample
intervals are displayed with two marks (for example, two arrows) to show the
start and end points of sample intervals, as is shown in Figure 24. If the two
clicks cover a lost core interval, an error message will be displayed and the
sample selection attempt will fail.
When the Annotation Module is activated and the program is in annotation mode,
the sample marks will be automatically moved out of the depth registration
rectangles and placed at some defined distance above the top of the rectangle
within which they reside in the sample selection mode. Lab analysis results
may
also be displayed or annotated on the digital core images, beside the sample
label and number, which is very useful for any lab result quality checking.
Sample registration values can be edited or deleted in a manner similar to
core
depth registration. A sample list table with corrected top/base depths and
sample length can be exported in different text formats at step 60. NA (Not
Analyzed) intervals and lost core intervals can be included in the table so
that the
lab can directly use the output in their lab report, saving the lab a few
hours in
manually generating the similar output.
VSH CALCULATION
The use of digital core images throughout the process, however, adds
additional
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functionality to the ADFM process. Geologists often need to determine the
volume of shale (VSH) in a given oil sands core in order to assess oil sands
reservoir quality, and the ADFM VSH Module provides a novel means of achieving
that goal. Bitumen-saturated oil sands are essentially black in colour, while
shales are light to dark grey. This characteristic feature of oil sands makes
calculation of VSH directly from digital core images possible.
Regions of the digital image are selected at step 64 to represent sand, shale,
dark shale and water/gas sand. These selected regions of the digital images
are
used by the program to generate Red, Green and Blue (RGB) histogram curves
for each corresponding rock type in a sand/shale calibration window (see
Figure
26).
Referring to Figure 26, based on the histogram curves for different kinds of
rock
types, the user specifies Red, Green and Blue (RGB) threshold values for shale
and dark shale. Threshold values are displayed as interactively-movable (by
means of the mouse) vertical lines on the RGB histograms which essentially
divide the RGB index of 0 to 255 into four regions: sand, dark shale, shale
and
gas/water sand, from which the VSH can be determined:
VSH = (shale region + dark shale region)/(all four regions)
After the four regions are defined, the top and base of a cropped image
interval
can be specified so that the raw core image and interpreted sand/shale (in
black
and white) of the interval can be displayed side by side to allow assessment
of
the validity of the selected threshold values. When the threshold values are
changed, the sand/shale interpreted image is updated accordingly.
The user specifies VSH calculation options (as can be seen in Figure 27),
which
options include Sampling window (the depth interval of cropped images within
which all pixels will be included to calculate VSH) and Sampling step (the
depth
difference between two nearby VSH value points).
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Using the top depth of the shallowest cropped image as the starting point, the
program calculates VSH at the depth for every sampling step, based on RGB
threshold values for shale and dark shale as determined in the calibration
step
and the VSH calculation formula discussed above. The sampling window is the
interval of images centred around a sampling point. If the sampling point is
within a lost core interval, no value is calculated. If the sampling window
includes
lost core, the lost core interval is ignored.
With the threshold values determined, a pixel that has RGB values within shale
or dark shale RGB regions is classified as shale; outside the ranges is
classified
as sand. The program then calculates a VSH value at every VSH depth point and
with all pixels in the corresponding sampling window, and plots a VSH curve in
the
VSH track in the Depth Correction Window (see Figure 28) at step 65. The VSH
curve can be exported in the LAS format, a commonly used industry standard for
recording well logs data, at step 66.
VSH calculation and display is handled by the VSH Module in the ADFM System.
FACIES INTERPRETATION
Oil sands projects are capital-intensive and oil companies spend considerable
funds and effort in trying to characterize oil sands reservoirs, including
building
3D facies models. Traditionally, 3D facies modellers spend 60 to 70% of their
time and effort in compiling data in an appropriate format to enable them to
load
the data into their 3D facies modeling software. The ADFM Facies Module is
designed specifically for generating facies results that can be imported into
many
3D facies modeling software programs.
According to the preferred embodiment, the user defines a facies at step 67 by
means of facies code (ID), facies colour, facies name, and minimum and
maximum VSH cut-offs (see Figure 29). The facies code is unique and can be
composed of a number, letters or a combination of both. Two facies columns are
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preferably provided on the Depth Correction Window, adjacent to the stacked
digital core images, displaying the user's facies determinations (as described
below). Once the various facies are defined by the user, facies can be
interpreted automatically (step 68 of Figure 5) or interactively (step 69 of
Figure
5). Facies can be auto-filled in one facies column in the Depth Correction
Window based on the calculated VSH curve and facies VSH cut-offs, and the
automatically-filled facies can be modified interactively by the user. Facies
can
be copied from one column to the other.
An interactive facies interpretation process is shown in the flowchart of
Figure 30.
The user enters the interactive mode at step 300 by selecting an interactive
menu or by clicking an interactive icon, whereupon a floating window showing
the
defined facies list is popped up (Figure 29). The user then selects a facies
from
the floating window at step 301, places the mouse cursor over a facies column
or
core image at step 302, and clicks on two points on the facies column or core
image to define the top and base depth of an interval at step 303. If the
mouse
action is in Facies Column 1 (step 304a), the program sends the facies ID and
top/base depths to Facies Column 1 at step 304b. If the mouse action is
alternatively in Facies Column 2 (step 305a), the program sends the facies ID
and top/base depths to Facies Column 2 at step 305b. If the mouse action is
alternatively on a digital core image in the Depth Registration Window (step
306a), the program sends the facies ID and top/base depths to a facies column
in the Depth Correction Window at the user's choice at step 306b.
The selected interval is then filled with the predefined facies colour of the
selected facies in a corresponding facies column at step 307, and the facies
file
is updated and saved at step 308. Any previously-established facies within the
interval is replaced with the new facies. If facies above or below the
interval are
the same as the new facies, they will merge into one facies interval. If the
new
interval is inserted in the middle of an existing facies interval, the
existing facies
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interval is split into two intervals divided by the new facies.
Where two geologists are engaged in facies determination and each provides a
facies interpretation of the core on the same well, the program can provide
two
parallel facies columns in the Depth Correction Window with one facies ID
column or two displayed beside the facies columns. If there is only one facies
ID
column, the displayed facies ID can be associated with either facies column.
Each geologist, being a separate user, would independently access the ADFM
system and conduct their own facies analysis. If desired, one geologist can
copy
the other geologist's facies column over to his own column and then make
changes to the copied facies. This is extremely useful, for example, where a
senior geologist is engaged in quality control of a junior geologist's facies
interpretation; the senior geologist can make changes on his own facies column
without losing the junior geologist's work. It is also very useful for an
office
geologist when refining an external consulting geologist's interpretation.
A core/facies description column (or "notes") can also be added adjacent to
the
facies columns) for the user to type in a description of the interval.
Horizontal
lines can be drawn in the description column to divide different description
text
blocks, as can be seen in Figure 28.
Finally, facies information can then be exported in text/table or LAS format
at
step 70 and the data uploaded to the data server at step 71. Once the facies
file
has been updated and saved at step 308, the user can exit the module at step
309.
DEPTH CORRECTION WINDOW EXPORT
Information can be exported by the program by means of text/table or LAS
format, but the Depth Correction Window itself can also be exported. Any
column in the Depth Correction Window can be turned on or off, and the width
and orders of columns can be changed at any time by the user. The content
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displayed in the Depth Correction Window can be exported as a digital image in
any format or in a .pdf file.
Referring now in detail to Figure 28, the columns of the Depth Correction
Window
available for export are as follows:
1 ) Gamma: (1 ) 0 - 150 API from left to right or 150 - 300 API; (2)
depth/unit
lattice;
2) Depth: (1 ) display scale and depth values; (2) depth value display
depends on scale;
3) Density porosity (DPHI) and neutron porosity (NPHI) on the same track:
(1 ) fraction scale from 0 to 0.6; (2) curves in different colour;
4) Resistivity: (1 ) display shallow, medium and deep resistivity curves in
different colours in log scale; (2) 0.2 - 2000 ohm.m;
5) Borehole imaging column: display borehole imaging logs, such as
Formation Micro-Imaging (FMI);
6) Correlation columns which display the correlation lines that connect the
corresponding markers on the well logging data and the stacked core
images, and the correlation lines can be turned on or off;
7) Core image 1: (1 ) display cropped images according to their raw depths
and the depth scale;
8) Image identifier: (1 ) display identifier of cropped images on core image
column 7 and (2) draw a line between cropped images of column 7;
9) Core image 2: (1 ) display cropped images according to their raw depths or
corrected depths and depth scale;
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10)Image identifier: (1 ) display identifier of cropped images on core image
column 9; (2) draw a line between cropped images;
11 )VSH column: (1 ) display the VSH (volume of shale) curve in fraction scale
of
0-1; (2) highlight selected VSH cut-offs defined in facies definition by the
user in different colours;
12)Facies column 1: (1 ) Colour fill facies;
13)Facies ID column: (1 ) display facies ID associated with Facies column 1 or
Facies column 2 at the user's choice; (2) draw a horizontal line between
neighbouring facies intervals;
14)Facies column 2: (1 ) Colour fill facies; may be identical to Facies 1 or
present an alternative interpretation, at the user's choice;
15)Sample column: (1 ) display sample intervals; (2) if lab results are
available, display lab results as a curve or histogram;
16)Notes: (1 ) multiple comments blocks divided by horizontal lines.
TEXT INFORMATION EXPORT
In addition to the ability to export the Depth Correction Window itself, the
program enables the export of information in text form. An Export function is
provided to enable the export of information relating to corrected core
depths,
VSH values, and facies. The user can choose what information combination from
designated wells) to export from a well list, the information including:
a. Core depths: export corrected core box depths.
Format: Core No., Box No., Top depth, Base depth,
Core corrected_length, Core_physical_length, Length difference
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b. Sample list with corrected sample depths and lengths. Lost core intervals
and NA (Not Analyzed) intervals can be included, as well.
Format: Sample label, Sample number, Top depth, Base depth,
Sample thickness
c. VSH and Facies curves: export VSH and facies information in an industry
standard LAS format.
Format: Depth, VSH, Facies code, Facies name
d. Facies only: export facies in the interval format. For every facies
interval
on a facies column in the Depth Correction Window, there will be one row
of data.
Format: Top depth, Base depth, Facies code, Facies_name
ANNOTATED DIGITAL CORE IMAGE EXPORT
Composite images can be generated in any digital format. Composite images
can include raw core images overlaid with different kinds of labels, such as
sample labels, top/base depths of core intervals, meter depths, and image
frame
with information such as company name, well name, company logo, scale bar,
etc. If lab results for samples are available and facies have been
interpreted,
sample results and facies ID can be annotated on the images, as well. Any kind
of label can be turned on or off at the user's choice.
The foregoing method is preferably applied within a system including the
modules as set out in the schematic illustration of Figure 4, which schematic
illustration illustrates the data flow. The flowchart of Figure 5 illustrates
the entire
preferred ADFM process as described in detail above.
As is clear from the foregoing, there are substantial advantages to the
present
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invention when compared with traditional core logging techniques. As can be
seen in Figures 1 and 2, which respectively illustrate the ADFM Digital Core
Workflow and Traditional Physical Core Workflow, the ADFM Digital Core
Workflow using digital images in initial depth registration and throughout the
remaining processes can result in substantial time savings and reduce the
number of people involved. The composite impact is an efficient digital
workflow
with which information can be quickly and remotely processed, and the results
can be delivered promptly to oil companies.
While a particular embodiment of the present invention has been described in
the
foregoing, it is to be understood that other embodiments are possible within
the
scope of the invention and are intended to be included herein. It will be
clear to
any person skilled in the art that modifications of and adjustments to this
invention, not shown, are possible without departing from the spirit of the
invention as demonstrated through the exemplary embodiment. For example,
the method could be embodied in a software product that a user could purchase,
rather than utilising a password-protected on-line environment. The invention
is
therefore to be considered limited solely by the scope of the appended claims.
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