Note: Descriptions are shown in the official language in which they were submitted.
.` 1174073
Methods and ApparatUS for Well
Investigation and Development
EDWARD L. BRYAN
STEVEN B. HUGG
TIMOTHY BREW~R
THOMAS M. CAMPBELL
LESLIE B. HOFFMAN
SPECIFICATION
This invention relates to methods and apparatus for
analyzing materials in or'from a well borehole and provid-
ing the results of the analysis as a function of borehole
depth, and for facilitating development of the well.
BACKGROUND OF THE INVENTION
One of the most complex and difficult problems in the
'overall task of obtaining oil or gas from beneath the earth's
surface involves the drilling operation itself in which a rotat-
ing drill produces a borehole one or several thousand ~eet deep.
Despite the impressive development in recent years of seismic and
other exploration techniques preliminary to drilling, the drilling
operation itself is one which still involves a substantial measure
of guesswork and estimation, based on the experience of the indiv-
iduals involved, because one can never know in advance exactly
what is being or will be encountered by the drill as it passes
through various formations. It will be apparent that various
factors such as drill rotation rate and loading must be varied
depending on the hardness and other characteristics of the forma-
tion being cut by ~e drill, but those characteristics are only
known from deductions from events apparent at the surface, such
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as the amount of vibration felt at the drilling table and the d~ill
advance rate which is known only after the drill has been working in
a specific formation for some interval of time. Thus, response to
changed conditions is slow.
It is also important to be able to know when to stop drilling
and use other techniques for recovery of oil or gas. Many fields
being drilled today do not involve reservoirs under such pressure
that oil suddenly appears at the surface. The oil must be pumped
or other techniques must be used to recover it from, for example,
oil bearing sands. Thus, partly because of the cost of drilling,
it is important to be able to determine rather quickly when a
formation of interest has been encountered and penetrated.
Still further, geological evidence can be used to identify
particular kinds of strata which are known to exist in a specific
relation to oil bearing formations. Such evidence includes litho-
logy composition, fabric such as grain size and porosity, structure,
ij paleontological data such as the presence or absence certain forms
of fossils, and also evidence of the pressure or absence of hydro-
carbons and in what form they exist, as well as numerous other data.
Much of this information is not obtainable at all, and that
which is obtainable is done so only by relatively expensive and
cumbersome techniques usually involving removing the drill string
and sending a special tool down the hoie to take a core sample
which is then brought to the surface and analyzed, or to "log"
the hole by electrical or radioactive techniques.
In 1928, the Schlumberger Brothers made the first electrical
well measurements in the Pechelbron oil field in France. Their
goal in doing so, and the reason that geophysical well logging
- has become a standard operation in petroleum explorations since
then, is due to the fact that it has been impossible to observe
the geological section exposed within an oil well by visual means.
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The following table presents a list of most of the conven-
tional logging techniques presently applied. It should be kept
in mind that these techniques have all been developed and are all
being used as substitutes for direct visual examination of the
sedimentary column in oil wells.
TABLE I~ CONVENTIONAL BOREHOLE LOGGING TECHNIQUES
1. Electrical induction log
2. Induction log
3. Guard log
4. Electrical log
5. Spontaneous potential log
6~ Density log
7. Mechanical caliper log
8. Gamma ray log
9. Compensated sonic log
10. 3-D Velocity log
11. Microquard log
12. Micro-electrical log
13. Dip meter log
14. Continuous direction log -
15. Neutron log
16. Micro-contact caliper log
17. Epithermal neutron log
18. Cement bonding log
19. Borehole camera
20. Seisviewer
21. Temperature log
22. Thermal neutron decay time log
23. Neutron/carbon log
24. Neutron activation log
25. SNAP/VA logs
During the fifty-two years since that first log, research
and investigation by geophysical well logging companies has shown
that certain physical parameters can be measured directly or calcu-
lated from the actual measurements taken down hole by well logging
tools. Those parameters which are directly determined are listed
in Table II, and other parameters which can be empirically determined
in an indirect fashion from geophysical well logging data are listed
in Table III.
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~ABLE II. PARAMETERS DIRECTLY DETERMINED BY
CONVENTIONAL LOGGING TECHNIQUES
1. True resistivity
2. Water and hydrocarbon saturation
~. Bulk density
4. ~orehole diameter !'
5. Mud cake thickness
6~ Acoustic transit time
7. Fracture indentification
8. Flushed zone resistivity
9. Flushed zone filtrate saturation
10. Mud cake presence
11.- Resistivity adjacent to borehole
12. Formation dip angle and direction
13. Borehole direction
14. Borehole angle of deviation from vertical
15. Carbon concentration
16. Elemental density ~O, Si, Al, Mg)
TABLE III. PARAMETERS INDIRECTLY ESTIMATED FROM
CONVENTIONAL LOGGING DATA
1. Water resistivity
2. Lithology, correlation
3. Porosity
4. Lithology, indentification
5, Permeability
6. Young's modulus
7. Shear modulus
8. Bulk Moduls
9. Poisson's Ratio
10. Hydrocarbon displacement
11. Formation structure
12. Location of Stratigraphic features
13. Recognition of sedimentary features
14. Depositional environment
15. Thermal history of basin
It should be noted that, in order for all of the parameters
listed in Tables II and III to be determined from geophysical well
logging data, twenty-five logs must be taken and subsequently
analyzed. It is also important to keep in mind that such important
parameters as correlation lithology, lithologic type and porosity
are not measured directly by any method currently in use. That
information, as well as samples from micropaleontological studies,
can only be determined through geologic analysis of mud cutting
or core samples.
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Core sampling, either in the axis of the drill string or $n
the sidewalls of the drill hole, is the technique which most nearly
approximates the geologic examination of outcropping rocks. However,
the difficulties in recovering a core sample and the expense involved
severely limit the use of actual cores. Also, due to the expense of
recovering cores, a complete analysis is warranted and at present
this is only done at a facility such as a core laboratory.
Accordingly, some attention has been given to observing and
analyzing material carried to the surface by drilling mud. As is
well known, a liquid called drilling mud, containing clays and other
materials, is pumped into the well, through the drill string, to
facilitate drilling and to carry cut and ground material away from
the drill bit, and that material is carried to the surface in the mud.
The term "drill mud return" will be used here to refer to the mud
as it emerges from the ~ell with the other materials. Normally,
the drill mud return is processed to remove cuttings, dumped into
a pit, and recycled down the string. Various substances are added
to cause the mud to have special characteristics of caking ability,
viscosity, etc., but these are of minimal interest here.
Of greater interest is the material carried by the drill mud
return which is that material cut or worn away from the bottom of
the hole by the drill bit or by the mud itself along with fluids
from formations penetrated which can be water, gas or oil. Interest
in this material is shown by U.S. Patents 2,591,737 to Souther, Jr.,
(1952) and 2,692,755 to Nowak (1954), which recognized the possible
value of such material and made some effort to gain information
therefrom. Souther was looking for evidence of oil in the mud
and disclosed techniques for steam-distilling mud samples to
extract vapors from crude in the return and detect evidence thereof.
Nowak extracted samples of mud, separated chips or cuttings there-
from and examined the radioactivlty characteristics thereof. The
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natural radioactivity was first measureland then the samples
were neutron irradiated and gamma ray activity was measured.
The readings could be correlated with depth.
While these techniques could provide useful information,
Souther was able to tell one only about the presence of crude
in return, and Nowak examined only radioactive characteristics.
Thus, these techniques are of quite limited value.
In addition to the discussions in these patents, it is
known that mud cuttin~s are regularly sampled by simple means at
the well site. At given intervals, the well-site geologist or
technician physically dips from the mud stream a small fraction
of cuttings which are then dried, cleaned and analyzed by simple
devices according to the methods given in the following table.
As will be recognized, the problems involved in this procedure
include the low rate of sampling, the level of competence of the
geological technician performing the analysis and the limited
data drawn from the procedure for application to overall geologic
analysis of the sedimentary column. The second and third of these
problems, of operator competence and limited data output, are par-
tially solved at present by sending sample cuts to a geologic
laboratory for further analysis. The overriding disadvantage of
this procedure is the time involved which ranges, currently, from
forty-eight hours to thre~e weeks.
TABLE IV. GEOLOGIC ~NALYSIS PRESENTLY PERFORMED AT WELL SITE
1. Rock type
2. Color
3. Grain or crystal size
4. Major characteristics (major minerals, fissility, etc.)
5. Minor characteristics (presence of heavies, microfossils, etc.)
6. Hardness
7. Approximate porosity
8. Oil shows
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The following Table summarizes the common procedures
involved with the laboratory analysis of both cores and mud
cuttings.
TABLE V. GEOLOGIC LABORATORY ANALYSIS
1. Fluid saturation by: retort method
hot solvent method
vacuum distillation method
2. Porosity by gravimetric method
3. Bulk volume by gravimetric method
4. Gas volume by: Boyles law method
Helium injection method
Resaturation method
5. Air Permeability
6. Heavy minerals by: magnetic separation
electrostatic separation
optical identification
7. Micropaleontological separation and analysis
8. Insoluble residue analysis
9. Micro-sedimentological examination
10. Xerogen color
11. Vitrinite reflectance
BRIEF DESCRIPTION OF THE INVENTION
An object of the present invention is to provide a system for
optically examining materials indigenous to the subsurface region
adjacent the drill bit, generating information signals about those
materials and providing that information to the individuals control-
ling a drillis~g operation.
A further object is to provide methods and apparatus for
developing optical signals representative of the materials, optically
and electrically processing those signals to enhance the useful
insormation therein and identifying characteristics of the materials.
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A further object is to provide methods and apparatus for
optically, automatically and promptly examining the materials at
the surface of the earth to generate the information signals.
~ Yet another object is to provide apparatus for optically
examining exposed surfaces of the borehole using optical fibers
for conducting electromagnetic energy to and from the investiga-
tion site.
Another object is to provide a method of conducting energy
to a downhole location at a depth to be developed for perforating
the well casing and adjacent formation.
Another object is to provide a method of generating steam
at the downhole location to facilitate recovery of hydrocarbons
therefrom.
Briefly described, the invention includes a method of analyz-
ing subsurface earth formations comprising the steps of providing a
stored data base including descriptive data on characteristics of
geological and paleontological features commonly encountered in
materials penetrated by a well borehole; optically examining material
indigenous to the subsurface region penetrated by the borehole and
forming signals representative of selected characteristics of the
material; comparing the signals formed following the optical examin-
ation with data in the stored data base to identify the nature of
geological and paleontological features present in the borehole;
and providing a display of those features identified.
In another aspect, the invention includes a system for
separating and analyzing materials from drill mud return for use
in combination with a well drillng apparatus of the type having a
drill string and bit, means for supporting and rotating the string
to drill a borehole, means for delivery drilling mud to the string,
and means for conducting drill mud return emating from the bore
annulus away from the borehole, the system comprising the combination
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of means for receiving and degassing at least a portion of the
drill mud return and capturing yas emanating therefrom; means for
analyzing the captured gas and providing a plurality of signals
representative of the presence of selected constituents in said
gas; means for continuously extracting a preselected percentage
of the degassed drill mud return; a plurality of serially connected
separation means for receiving said preselected percentage and
sequentially removing therefrom chips, particles and grains of
material in selected size categories; a plurality of optical
scanning means for receiving, respectively, the removed material
in each of said categories, for optically examining the material
for EMR characteristics and for providing signals representative
of selected ones of those characteristics; and data processing
means for receiving and storing said signols from said means
for analyzing and from said scanning means, correlated with
signals representative of drilling depth.
In order that the manner in wh~ch the foregoing and other
objects are attained in accordance with the invention can be under-
stood in detail, particularly advantageous embodiments thereof will
be described with reference to the accompanying drawings, which form
a part of this specification, and wherein:
Fig. 1 is a schematic simplified block diagram of a system in
accordance with the present invention;
Figs. 2A, 2B and 2C taken together are a functional block
diagram illustrating the architecture of the processing portion
of a system according to Fig. 1;
~ ig. 3 is a schematic diagram of a system for obtaining cutting
samples for processing in accordance with Figs. 1 and 2;
~ ig. 4 is a schematic perspective view of a sample preparation
and optical viewing apparatus;
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Fig. 5 is a sectional view along line 5-5 of
Fig. 4;
Fig. 6 is a side elevation, in section, of one
embodiment of an optical sample illuminating and viewing
apparatus usable in the apparatus of Figs. 4 and 5 and
- appears on the same sheet of drawings as Fig. l;
Fig. 7 is a partial side elevation, in section,
of a further embodiment of an optical sample illuminating
a viewing apparatus usable in the apparatus of Figs.
4 and 5;
Fig. 8 is a top plan view of the apparatus of
Fig. 7;
Fig. 9 is a schematic block diagram of a portion
of an optical image analysis apparatus usable in conjunction
with the apparatus of Figs. 2 and 4-8;
Fig. 10 is a simplified side elevation, in par-
tial section of a down-hole optical examining apparatus
usable in the system of Fig. l;
Figure 11 is an enlarged partial side elevation
of an optical foot portion of the apparatus of Fig. 10;
Fig. 12 is a side elevation of an embodiment
of a down-hole optical examining apparatus usable with
a drill string in place;
Fig. 13 is a bottom partial plan view of the
apparatus of Fig. 12, Figs. 12 and 13 appearing on the
same sheet of drawings as Fig. 8;
Fig. 14 is a graphical illustration of the chara-
cteristics of fiber optics usable in the system and
particularly the apparatus of Figs. 10-13; and
Figs. 15A-C taken together are an information
flow diagram or geological data bases usable in accordance
with the invention.
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OVER~LL INVESTIG~TION SYSTEM
~ ig. 1 shows a simplified block diagram of a system in accord-
ance with the invention, in a functional form, the system including
~ data base 20 which is interconnected with a pattern recognition
portion of an assembly of data processors 21. Optical examinat1on
apparatus 22 is provided to inspect lithologic materials and produce
a series of groups of signals which can either be initially in
digital form or optical form, subsequently converted to digital
form, as indicated by block 23, the digital signals to be supplied
to data processors 21. Drilling operation data is also gathered,
including depth and other factors, as indicated at 24, and supplied
to the data processors. The pattern recognition processor analyzes
signals e~tracted from the data base and those supplied by the optical
examination and digital signal blocks and presents the results of the
pattern recognition analysis to a display device 25 which can be in
the form of a transitory display on a CRT or by printing of hardcopy.
The function of processors 21, in the rather generalized
context of Fig. 1, is to analyze each group of digital information
representative of characteristics of material optically examined
with reference to characteristics of known materials stored in data
base 20. The data processors then determine whether the analysis
results in recognition of the optically examined material as being a
material the characteristics of which are stored in the data base.
When this analysis results in recognition, the display unit 20 is
provided with a statement that the material is recognized and an
identification of the recognized material, along with the depth
to which the material is indigenous. The printout or display
presents this information together. If the analysis does not
initially result in recognition, the new pattern of characteristics
can be separately analyzed and added to the data base with suitable
identification. The ultimate purpose of the information to be
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presented is, in addition to recognition information, a statcment
of the significance of that recognition, i.e., whether it indicates
the likelihood of the presence of oil or gas of no such substances.
In addition, the signals from generator 23 along with the
drilling operation data are provided to a data store 30 which is a
high density storage unit for the purpose of receiving and storing
all data relating to a specific borehole for possible different
forms of future analysis. As will be recognized, the output of
processors 21 can also be provided to the same or a different high
density storage device to retain, in machine-readable form, the
results of the comparison process.
Optical examination can provLde a wide variety of information
relating to the characteristics of materials found in, or brought out
of, a borehole previously drilled or being drilled. For example, the
grain size, shape and distribution of various minerals can be opti-
cally determined, along with the porosity and the characteristics
of the minerals, i.e., whether they are predominantly sandstone,
shale, limestone or dolomite. In addition, microbiological charac-
teristics of fossils existing in the strata penetrated by the bore-
hole can be optically determined. As will be recognized, fossils
of various types have characteristic shapes and si~es, and these can
be determined by optical investigation.
The data base constitues a library of ~nown materials and
their characteristics as to shape, size, distribution, etc.; and
also the shapes and other characteristics of the microbiological
features which can yield paleontological data. The presence or
absence of certain fossil forms is indicative of proximity to
formations which can be expected to contain hydrocarbon deposits,
and the prompt recognition of such characteristics can be a valu-
able guide to the desirability o stopping or continuing drilling.
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The term "optical examination~ as used herein is not intended
to be limited to examination with visible light. On the contrary,
it is contemplated that various spectral regions of electromagnetic
energy will be used, including ultraviolet, visible light, possibly
infrared, and also scanning with X-rays for defraction and spectral
data.
A more detailed diagram of a portion of a system in accord-
ance with the invention is shown in Fig. 2, this figure also includ-
ing other examination characteristics including examination of the
gases derived, the gas analysis being particularly significant if
the materials under examination are derived from drill mud return.
Figs. 2A, 2B and 2C show the major processing portions of
the system and identify various items of hardware which are readily
available, are compatable with each other and which can therefore
be assembled to perform the necessary control and processing steps.
It should be recognized that the specific processors and other com-
ponents identified are, in most cases, not the only ones which can
be used and that functional equivalents can be substituted, if
desired.
A plurality of transducers 24 provide the various signals
representative of the drilling parameters including those from
which drilling rate, depth, mud flow characteristics and other
related information can either be directly determined or calculated.
As previously indicated, these parameters are important because it
is from them that depth and lag time can continuously be calculated.
These generally analog signals are supplied to a multi-channel
signal conditioning unit 31 which normalizes and ot~erwise condi-
tions the signals so that they are scaled as needed, depending upon
the choices of transducers used to make the measurements.
These analog signals are supplied to a 16 channel analog-to-
digital converter (~DC) which is one portion of a CAMAC crate 32.
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As will be recognized by those skllled in the art, the crate is a
commercially available powered enclosure and is the basic unit of a
computer automated measurement and control system (of which name
CAMAC is an acronym) based on a set of IEEE mechanical, electrical
and logic standards including standards 583-1975, 595-1976, 596-1976
Crate 32 includes, in addition to the ADC, a DEC LSI 11/23 processor
with an RSX 11/M operating system and DECNET distributed communica-
tion software. This unit is mounted in a Kinetic Systems 3923
-Processor Adaptor to become functionally compatible with the other
CAMAC modules. Also included in the crate is a 64K word memory;
a DLV-11J Quad Serial Port; and a DEC 488 interface which receives
input from a gas chromatograph 33 for analyzing gas supplied by the
sampling discussed in connection with Fig. 3. The crate also
includes a 24 bit digital input module to receive inputs from limit
switches on a sample preparation and analysis apparatus 34, to be
discussed with reference to Fig. 4; a 24 bit relay control output
module to supply relay signals for control of apparatus 34; a
16 channel ADC to receive and convert to digital form position
information from the sample preparation apparatus; and an 8 channel
digital-to-analog converter for supplying analog control signals
to motors and othercomponents of that apparatus.
Crate 32 communicates with other processing portions of
the system through the DLV-11J Quad Serial Port, one port PO of
which is connected to one port of a similar quad serial port in a
master crate 35 (Fig. 2C). A second port, P1 of crate 32 is con-
nected to a quad serial port in a crate 36 in a microprocessor
based data processing subunit 37a ~Fig. 2B) for image analysis
system control and data processing. The overall system includes
a plurality of subunits like subunit 37a, ~our such subunits being
shown in Fig. 2B~ Unit 37a ana]yzes chips while units 37b, 37c
and 37d analyze sand, silt and clay, respectively. ~hese subunits
~rader~cl r k
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are substantially identical and, therefore, only unit 37a is
shown in detail.
Crate 36 is of a similar nature to crate 32 and includes
three 3923 crate controllers, one master and two auxiliaries;
three LSI 11/23 and processor adapter units; three 64K word
memories; two DLV 11J Quad Serial Ports; a 24 bit digital in-
put-output interface unit; a three channel step motor controller;
. .
a video digitizer; a 128~ wbrd buffer memory; and RL02 disk con-
troller: and two DL11 Serial Ports, all organized as illustrated.
The 24 bit digital I/O unit interfaces with an image analysis
system preprocessor 38 which can be an Omnicon Alpha 500. This
unit receives optical inputs from an optical system 39 connected
~, 1,.; c 0"~ - , ...
through fiber optics to a chaln~e~n v-idèo camera 40 which produces
a sequence of images in a form compatible with the 500. The output
of preprocessor 38 is a composite video signal which is delivered
to the video digitizer unit in crate 36.
The three channel step motor controller is connected to the
optical stage and focus control 41 which operates in conjunction
with optical system 39. The RL02 disk controller operates a 10
megabyte disk drive which is the image work file storage location.
The subunits 37a-d are interconnected through one of the
quad serial ports, port P1 being connected to port P1 of crate 32
and port P3 being connected to port P1 of the next processor, these
being 9600 baud communication links. Port P2 in each crate is a
960Q baud diagncstic port, and port P0 in each crate 36 communicates
through one port in a DLV 11-J quad serial port in crate 35. For
reasons of capacity, the DL 11 serial ports are coupled to the second
DLV 1~-J quad for intracratc communication. It should also be noted
that the top DEC LSI 11/23 microprocessor runs an RSX 11/D operating
system used for crate communication, crate control, position stage
and ~ocus control, ~lpha control and ~lpha data collection. The
de r~ c~rks
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second and third LSI 11/23 microprocessors perform vldeo image
processing and Alpha data processing for classification of
physical characteristics of specimens.
- Turning now to Fig. 2c, i~ will be seen that crate 3S
includes three 3923 crate controllers ~one master and two
auxiliaries); three LSI 11/23 and processing adapters; three
64K word memories; a 300 megabyte disk 43; three DLV 11-J Quad
Serial Ports; a 20 megabyte fixed head disk controller which
controls and communicates with a DEC 20 megabyte fixed head disk
4~; an FPS 120 controller coupled to an FPS 120 floating point
and array processor 45; a DL 11 serial port; an RL02 disk control-
ler operating with an RL02 ten megabyte disk and drive 46; a 300
LPM printer controller communicating with a Printronix 300 P line
printer 47; and a color graphics controller communicating with
a Ramtek Color Graphics CRT 48. The bottom quad serial port
communicates with a data display CRT 49 such as a Lear Siegler~
ADM3A and, through a fiber optic link including two fiber optic
transmitter/receiver units, with a data CRT 50 located at the
drill platform.
The top LSI 11/23, running with RSX 11/M operating system,
provides loading on all other processors of the crate using DECNET
protocol, control of the other processors and maintenance of data
bases. The second LSJ 11/23 (also running RSX 11/M) provides access
to the floating point peripheral processor for processing pattern
recognition routines as well as the geological ciassifier analysis.
The bottom LSI 11/23 provides graphics and data output functions.
As will be described hereinafter, the system; when used ln
conjunction with flowing mud to analyze the materials extracted
from drill mud return, includes an agitator for removing gas from
the mud and analyzing that gas. Thus agitator fluid level and the
degassed mud weight or density and characteristics of the samples
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of degassed mud, such as dcnsity, flow rate and thc like, can be
supplied.
It is important to continuously track the characteristics
of the well itself during drilling, which characteristics can be
continuously changing. When analyzing materials derived from drill
mud return, it is important to continuously keep track of the depth
from which materials are being brought to the surface. In order
to determine this, it is necessary to know the depth of the well,
along with the mud flow rates and the like, from which the delay
in bringing the material from the locations adjacent the drill bit
to the surface can be determined. Thus, the total depth of the-
well, determined from the number of sections below the kelly and
the position of the kelly must be known to give a depth. The casing
depths and diameters along with pipe lengths and diameters must also
be known for calculatinq the total well volume. This, in conjunc.ion
with the mud flow rates, permits calculating, with reasonable
accuracy, the depth from which the materials are derived at any
given time.
The geological data base (GDB) includes high speed disc data
storage in units 43 and 44 operating with the recognition proces~or
which accesses to the central managing processor to obtain processed
data from the optical, chromatographic and other analysis and make
~comparisons~ with the data found in the data base storage.
The GDB is a matrix of geologic information through which
geoloqic parameters may be classified to produce a new set of
specific characteristics of greater substance than was possessed
by the oriqinal input parameters alone.
A simple example will illustrate this concept. If an
analysis describes particles of quartz sand of a certain size
and angularity, that information alone has no true significance.
However, whcn applied throu~h a matrix of information based on the
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geomorphological principle-~that detrital sedlmentological material
becomes smaller in size and more well-rounded as it is transported
by fluvial prosesses from its source, then the size and shape
characteristics of the sand that was analyzed produces an indica-
tlon of the location of the sample point with respect to the source
of the sand.
Three types of GDB's can be constructed. They are: areal,
columna~, and a combination. The areal data base contains informa-
tion with respect to geologic materials and conditions over a hori-
zontal area. The columnar data base contains similar information
through a vertical scale. ~he combination GDB contains both areal
or horizontal and columnar or vertical information.
It should be kept in mind the difference between physical
location and chronologic relationship in stratigraphic relation-
ships. A transgressive shore line will produce a continuous areal
deposition, but the time o~ deposition of those sediments varies
across the area. In a similar sense, the columnar or vertical GDB
will be based intrinsically upon the overriding ~rinciple of strati-
graphy, that is, super-position. The principle of super-position
simply states that that which lies above came later. This principle
is Yiolated only through structural realignment by faulting or over-
turned folds.
Examples of these three types of geologic data bases can be
given. A structural contour map is an areal data base. A strati-
graphic column is a vertical data base. The complete stratigraphic
analysis of a depositional basin in area, depth and time combines the
characteristics of both. Numerous geologic data bases have been
formulated, but are not in a computerized format.
- ~owever, within the past 15 years, numerous applications of
the concept of constructing a data base covering a defined and
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partially explored region, with automatic data processing as a
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basic constraint, have been performed. A computerized data base
of all geologic, geophysical, petrological and hydrographic data
for the entire surface of the United Republic of Tanzania is in
compilation at this time.
Of particular usefulness and relevance to the system dis-
closed herein are several available data sources from which diff-
erent forms of data can be drawn to form a GDB for the present
system or for other purposes. These sources are well known to
geologists and exploration companies and are widely used. Two
of these data bases, known as API and GEOREF, are available through
,,;. .
O~BIT System Development Corp., 25~0 Colorado Ave., Santa Monica,
California. In addition, considerable data is available from the
Texas Well Log Archive, at the University of Texas, Austin, Texas,
and the Petroleum Data System, University of Oklahoma, Norman,
~klahoma. Related data is also available from numerous commerical
organizations such as T-D Velocity Trades, Inc., 2400 McCue, Houston,
Texas.
Two specific but interrelated forms of GDB can be employed.
One is for developmental fields, and the other for exploration
plays.
The Development GDB is defined with respect to specific
basins including known reservoirs, and already documented strati-
graphic columns. It contains areal and columnar relationships
correlative to known geology throughout specific basins matrixed
against characteristics which are essentially equivalent to para-
meters measured. Therefore, given sets of measured parameters
in a new well within a basin under development, automatic syn-
thesis through the Development GDB will produce information as
to wherein space (position in the basin and in the lithos~rati-
9raphic column) and time (chronostratigraphic position) is any
part of the well being drilled or logged. Additionally,
c.Jen~ 5
--19--
il74073
qualitative in~ormation ean be directly analyzed from the para-
meters and indirectly through correlation with the GDB matrix
regarding the reservoir charaeteristies within zones intersected
by the well.
The Exploration GDB will be defined with respect to general
eoneepts of sedimentary environment, and global or regional strati-
graphy. In its first applieation in a given area, the Exploration
GDB will eorrelate the parameters measured wi~h those general
eoneepts, then gradually will grow towards a form of Development
GDB. The eonceptual basis of the Exploration GDB is to rebrder
and rationalize measured pa~ameters from the standpoint of general
stratigraphie theory to provide a eontinuously updated environmental
model of the sedimentary eolumn through which the well is being
drilled. ~
Both forms are based, not onl~ upon specific and general
stratigraphic information and theory, but also take into aecount
other related diseiplines ineluding seismie stratigraphy and the
mieropaleontological aspects of biostratigraphy. It will be reeog-
nized that the information derivable from se~eral wells in a speei-
fic basin ean be correlated to produee a three dimensional repres-
entation of the stratigraphy in that basin, giving increasingly
reliable and useful information about that specific basin as the
number of samples increases. Further, information about a basin
ean be applied to other basins whieh show similar stratigraphie
eharaeteristics even though they lie in other parts of the world.
Thus, the system is eapable of permitting predictions in new
fields, much more expeditiously than has previously been possible.
~ ig. 3 shows, in a rather schematic diagram, a system which
ean be employed to recover and separate materials from drill mud
return for analysis. To the left of Fig. 3 some of the basic
clements of a drilling mechanism are shown including the well
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~ 174073
and casing 60 and a drill string 61 wh~ch extends into the well,
the string havinq a bit 62 at the lower end thereof forming the
hole. The string is rotated by a drilling table 63 in a well-
known manner.
Drill mud is normally accumulated in a suction pit 64 and
extracted therefrom and conveyed through a conduit 65 by a mud
pump 66 and into the drill string, under pressure, to assist with
the drilling operation. The mud emerges through bit 62 and flows
upwardly in the annulus surrounding the string. This drill mud
return is extracted through a conduit 68 and, in the normal system,
is processed and returned ultimately to a settling pit 69 which
leads bac~ to the suction pit for reuse of the mud.
In the system of Fig. 3, the mud is delivered to a degassing
a~itator indicated generally at 70 in which the mud is forcibly
agitated to permit gasses trapped therein to emerge into the upper
portion of the agitator chamber. Any such gases are extracted
through a conduit 71 and at least a sample thereof is delivered to
a gas detector and gas chromatography apparatus for analysis as
previously described. Excess gas can be bled off through a conduit
72to a flare.
The degassed mud is conveyed through a conduit 73, the den-
sity thereof being measured by a density measuring device 74 in the
conduit. The mud is then split in a flow splitter 75 and a portion
thereof is delivered through a conduit 77 to a series of separating
devices. Devices 78 and 79 are connected in conduit 77 to measure
the sample density and the sample flow rate for delivery to the data
processing equipment. The remainder of the mud, other than the
sample, is conveyed through a conduit 80 to a decanting centrifuge
81, The coarse materials from the drillmud return are conducted
through a conduit 82 to a waste pit, and the remainder of the mud,
containing fine sand and silt, is conveyed to a series o separators
-21- -
11 17~73
~ndicated generally at 84 for removing sand and silt and for salvag-
lng barite rom the mud, the partially cleaned mud being returned
through conduit 85 to the settling pit 69. After settling, the
mud can then be reconditioned by the addition of various materials
in the suction pit for reuse.
The degassed mud sample on conduit 77 is delivered to a series
of separators 87a-87f which, sequentially, remove chips, coarse sand,
find sand, coarse silt, and fine silt, the final separator being a
clarifier to remove clay which may remain in the mud. The outputs
of these separators are lar~ely dewatered particulate materials in
the various sizes as determined by the separators, and the particu-
late fractions are delivered to individual dryers 89a-89f. Each
dryer is a continuous belt drying filter in which a continuous
conveying belt carries the chip, sand silt or clay fraction supplied
thereto through a chamber which is subjected to a vacuum, each
chamber being coupled through a conduit 90 which is connected to a
wet-type low vacuum centrifugal pump 91. Clarified water from
separator 87f and water extracted by pump 91 are delivered for
disposal or to a liquid chromatograph for further analysis through
a conduit 92.
The dried particulate material fractions are removed from
the drying chambers and delivered to further splitting devices
93a-f each of which extracts a sample, through conduits 94a-f to
be delivered to optical scanning equipment. The remaining material
not included in the sample is conveyed to crushing equipment wherein
the particles are crushed, in the case of the chip and sand frac-
tions, and grinding operations, in the case of the ship, sand and
silt, so that the material can be subjected to X-ray analysis.
The clay fraction sample is delivered directly to X-ray analysis,
the remainder thereof being discarded.
.
-22-
~ 1 7 407 3
.
As previously indicated, a primary objective of the systems
of the present invention requires on-site automatic logging and
~eological assessment of drilling operations from either surface
or down-hole methods to help the on-site geologist. Since it has
been reco~nized that optical methods provide sufficient information
to replace present petrological and logging techniques, the optical
methods must be incorporated in a system to meet this primary objec-
tive. In order to be applicable to both surface and down-hole appli-
cations, the system is based on a hybrid of mechanical, optical,
electrical and computer subunits. Although the sensin~ mechanism
and specimen surface preparations will be different for the surface
and subsurface configurations, th~ data processing portion of the
system is essentially consistent. Thus, the system is divided into
three major system areas, specimen preparation and optics system,
processing optics systems, and data processing system.
The specimen preparation and optics uses, in part, methods
developed for petrography and optical mineralogy adapted to geo-
logical samples. These methods require automation to provide on-
site automated operations.
There are three generally accepted forms of useful petrol-
graphic samples, each one lending itself to different types of
inspection techniques. One such type is the thin section
(0.3 millimeter), a second is the one-sided polished section,
and the third is the granular sample. The thin section combines
the advantages of transmitted light and reflected light examina-
tion. ~owever, its preparation by totally automated techniques
is, at the present time, more complex than the results justify,
primarily because considerable hand manipulation and finishing
is necessary, making the preparation overly labor intensive and
therefore less attractive.
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~ he one-sidcd polished section performs well in reflected
light analysis and in addition lends itself to cathodoluminescence
techniques. An apparatus for preparing sections o this type is
shown in Figs. 4 and 5, Fig. 4 being in a rather schematic form.
As seen in these figures, the apparatus includes a track 100
which is generally circular and can be continuous, although it
is illustrated in Fig. 4 as having an interruption for the re-
moval and replacement of sample-holding platforms. A ring gear
101 extends concentrically below the track and is supported in
fixed relationship with respect to the track. The tracX supports
a plurality of platforms 10~, only one of which is shown in Fig. 4,
each such platform having wheels 103 to ride on the upper, flat
surface of the track, a support and drive structure 104 extending
downwardly from the platform through an annular gap 10~ in the
track itself. The drive can include a motor driving a pinion
gear 106 which engages gear tO1 so that when the motor is ener-
gized the platform is driven around the track. Laterally extend-
ing guide wheels 107 attached to the support mechanism prevent
lateral movement of the platform with respect to the track.
Each platform supports, on its upper surface, a chip
binder mold 108 which can include a mold 109 made of a material
which can support the mold but permit release therefrom,a suit-
able arrangement for this component being a Teflon~surface having
.
transversely extending grooves or flutes.
The apparatus further includes a sequence of components to
supp~y, bind, grind and examine the specimens as they are carried
b~ the movable platform around the track. These are shown sche-
matically in Fig. 4 and include a chip supply 1tO which receives
chips from these drying and splitting devices 94a-f shown in Fig.
3 and can consist of a delivery hopper or conveyor having a lower
surface with a distributor for spreading a relatively even layer
J~ rk
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~ ~74073
of chips, granules or particles onto the Teflon surface of the
mold. As previously indicated, a plurality of platforms, sub-
stantially end-to-end, would be provided on the track to render
the system as continuous as possible. It should also be noted
that the chip supply can include, or be preceded by, an impreg-
nation device for impregnating the specimen pores with a liquid
which sets to give a hard, easily polished product, one such
liquid usable for this purpose being methylmethacrylate. This
preparation may not be necessary for many forms of specimens,
but would be particularly appropriate to those forms of mineral
deposits which are relatively easily broken up or otherwise
destroyed in the absence of a compound of this type.
After spreading of the specimens on the mold, the mold is
delivered to a station including a binder supply 111 which dis-
penses onto the mold and specimens a binding material capable of
relatively rapid setting to form a plate containing the specimens.
A suitable binder for this purpose is a low melt temperature die-
cast alloy such as alloys normally used in die casting having lead
and tin as primary components. It should be recognized that this
material is reusable.
It will also be recognized that polyester and epoxy resins
can be used, such components being selected for short setting times
and, since they would probably not be reusable, l~w cost.
Following this station is a setting air supply which provides
either cooling or heating air onto the surface of the particle and
binder mixture, cooling air being chosen if a low melt temperature
alloy is employed as the binder, and heating air being chosen if
the binder is a curable thermo-setting resin.
The specimen arrays produced by using these binders in the
manner described will be submitted to analysis by reflected light.
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~ 174073
Accordingly, the surfaces thereof must be polished to a degree in
order to permit this inspection. For this purpose, a plurality of
grinding drums, such as drums 113 and 114 can be provided to engage
and grind the exposed surface of ~he specimen plates. These drums
are provided as being exemplary, and it will be recognized that belt
~rinders or other forms of grinders can be used. Of significance is
the fact that the qrinders are of graded fineness, i.e., a rough
grindin~ drum is followed by a smoother one, etc., until the desired
degree of flatness and polish is achieved. It should be noted, how-
ever, that the polishing is not intended to achieve anything approach-
ing optical flatness but, rather, is to reach a rather uniform degree
of flatness so that the results of the investigation will not be
altered by irregularities.
A cleaning station 115 which can include one or more vacuum or
positive pressure air-jets, follows the grinding stages to remove
loose material from the surface, afterwhich the sample plates are
passed under the optical examining stage indicated at 116. At stage
116, the polished surface of the specimen plate is illuminated with
light of desired wave lengths, and light emanating from the specimens
is received. After the optical examination, the specimen plate is
removed and can be preserved for archival purposes or, particularly
if the alloy binder is used, subjected to heat for recovery of the
binder and discard of the mineral material. The platform is then
recommenced on a new journey around the trac~.
~ iq. 6 shows, in greater detail, a portion of an optical
examinin~ apparatus 116 usable in the apparatus of Fig. 4 and
includes a support 120 lying above and subs~antially parallel
with the upper surface of the specimen plate 109, the upper
surface of which has been ground and polished. Support 120 has
~p~rtureS therein for receiving a plurality of fiber optic
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.
~17~73
connectors 121a-y, each of which extends transversely perpendicular
to the path of travel of the specimen plate, the general direction
o~ which is indicated by arrow 122. Each fiber optic connector
contains a plurality of optical fibers, the flat ends of which are
exposed so that they face downwardly toward the specimens. Selected
ones of those connectors can also be disposed in generally concave
portions of support plate 120 as shown at 123 to receive connectors
such as 121c and 121d.
Connectors such as 121c are coupled to at least one source
of electromagnetic energy 124 which provides light of a preselected
wave length to illuminate a portion of the surface of specimen
plate 109, and the fibers associated with connector 121d are con-
nected directly to one of a plurality of receivers 125. Thus,
light emanating from the exposed ends of the fibers in connector
121e illuminate the specimen region and the receivers receive
light emanating therefrom, either re1ected or as a result of
luminescent activity in the specimens.
Connectors such as 121a and b are arranged so that a selected
umber of those fibers convey light from sources 124 to the specimen
the same or
surface, while/other fibers in the connector are coupled to receivers
125. With this arrangement, regions of the sample plate surface can
be illuminated with various wave lengths of light and images result-
ing from that illumination are conveyed by optical fibers to the
receivers for analysis. Because of the provision of a plurality
of the connectors, and the arrangement of those connectors extend-
ing substantially entirely across the specimen plate surface, each
specimen plate can be investigated using as many different wave
lengths as are needed to consider various reflectance and lumines-
cence characteristics of the specimens contained therein, as plate
109 is con~inuously or step-wise carried under support 120. It is~
27
c~
~ 17~073
of course, important that each set of samples be depth correlated
so that the optical input information is referred to the depth from
which the samples came.
~ igs. 7 and 8 shows a further embodiment of an optical examin-
ing apparatus which can be used in addition to that shown in Fig. 6,
or in place thereof. This apparatus includes a substantially hemi-
spherical shell 126 having a plurality of fiber optic connector
locations127r each including an objective lens 128a and a connector
body 128b which receives and holds at least one light transmitting
optical fiber 129t and at least one receiving fiber 129r. The trans-
mitting and receiving (or source and image) fibers are connected to
a number of receivers and selectable light sources as generally
described with reference to Fig. 6. The locations 127 are arranged
on radii and concentric circles of the hemispherical shell 126 to
transmit light and receive reflected light at known angular relation-
ships so that angle-related reflectance characteristics of the speci-
men material positioned under the hemisphere can be determined.
The receivers, being coupled to a relatively large number of
fibers, are the initial input to the portion of the data process-
ing system which will analyze the characteristics of the specimens.
The data processing system extracts information via the optical
system from prepared specimen surfaces and then interprets the
information. The system is an integration of optics, video
and digital units. At this stage, it should be noted that selection
of the data processing system encompasses the selection of process-
ing methods. It is possible to use substantially pure digital
processing or a mixture of optical processing and digital processin~.
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~174073
.
Whereas optical processing provides the fastest methods,
digital methods provide the most flexible. Optical process-
~ng is analogous to analog computing, whereas digital
methods rely primarily on numerical and discrete sample
data analysis computing techniques. Geological assessment
of data, as well as presentation of reduced data, requires
digital computations.
Digital processing requires transformation of the optical
signal into a matrix of discrete points, called "pixelsn. The unit
which performs this operation is typically a video camera and video
to digital converter for image inf~rmation. Additionally, new
solid state arrays using charge coupled device technology are also
used. Once the optical information is converted to a sampled digi-
tal signal, standard computer processing techniques are used. Since
a typical stored image matrix contains 660,920 pixels, typical opera-
tions of this sort require an extensive number of multiplications
and additio~s requiring considerable computer execution time. Thus,
the hardware is capable of reducing the size of the image matrix.
Once the image has been analyzed, the data processing system
performs other analyses. At the same time, control of the entire
automatic processing machine must continue. Thus, the requirement
for parallel execution of processors arises. It is therefore high-
ly desirable to use the mixture of optical and digital processing,
using optical image processing to remove background and accomplish
initial processing which is a form of filtering, and then converting
the partially processed images into pixels which can be handled by
the digital data processing aspects of the system.
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~ ~4073
Since the basic premise of the system of the present invention
involves optical information in the form of images, either from an
objective lens on a microscope or as extended through the use of
fiber optics, the basic requirements for processing are the same.
Image processing techniques involve the spatial measurement of
features. Thus, an image is characterized in a two-dimensional
function by intensity, i.e., intensity as a function of X and Y
coordinates. This intensity is commonly called grey level.
Digital techniques parallel temporal signal processing in that
the image intensity is sampled at some X and Y interval. This
sampled point is called a pixel. Analog methods called optical
processing uses lens, mirrors and spacial filters to process
complete fields.
Fig. 9 shows an optical processor apparatus usable in con-
junction with the apparatus of Figs. 2, 6, ~ and 8 and includes
a multiple light source t30 which includes sources of light at
preselected wave lengths usable to determine characteristics
in the specimens prepared in accordance with Fig. 4. The light
produced by the source is passed through an aperture and lens
assembly to direct the light from source 130 along desired
channels. One or more rotating filter wheels 132 can be incorp-
orated in one or more of the channels to refine the wave length
selection, and the light can then be passed through a polarizer
assembly which is usable to produce polarized light in one or more
of the channels for extnction and other analysis. Finally, the
light is conducted to beam launch optics which is a coupling
mechanism for introducing the light into optical fibers such as
fibers, or groups of fibers, t35, 136 and 137 which are the
source fibers for optical assemblies 121a-y, discussed in connec-
tion--~with Figs. 6~ 7 and 8. It will be recognized that the fibers
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~ 17~073
lllustrated in Fig. 9 can be groups of fibers, and that many more
flbers than those illustrated would normally be employed.
The light received from the specimens and conducted through
the optical assemblies 121a-y is conveyed through image fibers
140-142 which, again, are illustrative of a larger number of
fibers, for connection to electro-optical mechanical multiplexing
assemblies 145a-y, each of which includes a movable coupler 146
and a drive unit 147, each of couplers 146a-y being movable to
align a portion thereof with a single output fiber or group of
fibers 148a-y. Couplers 146 are in the nature of optical selec- -
tor switches such as shown, for example, in U.S. Patent 4,239,330,
and permit selection of one or more fibers constituting the outputs
from the optical assemblies 121a-y, the outputs 148 thereof being
a number of selectable positions. Drivers 147 can be step motors,
or the like, capable of moving the couplers to the desired posi-
tion as a function of a digital input. Fibers 148 constitute the
input to a similar selector unit 150 including a drive 151-and a
coupler 152 to select the outputs from the selectors 145 for deliv-
ery to a microscope 154 having variable focus, the output of the
microscope being a partially processed image which is delivered
through an optical path 155 to the processing apparatus shown in
Fig. 2. A beam splitter 156 can be provided to sample a portion
of the image for delivery to a focus detection unit 158 associated
with a microprocessor and control logic unit 159. The microprocessor
and control logic is programed to sequentially select fibers by
supplying control signals to a fiber select unit 160 in accordance
with a preselected sequence, and to control the focus of micro-
scope 154 by a focus drive 161 which provides control signals to
a focus adjusting step motor 162.
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~ 174073
The optical and $mage processing combines optical physics
and digital sampling analysis techniques to process information
from an image. The present apparatus involves image analysis,
a general theoretical discussion of which can be found in the
text ~Theory and Application Digital Processing", Rabine~ and
Gold (Prentice-Hall, 1975), and "Digital Image Processing",
Castlemann (Prentice-Hall, 1979). Image analysis consists of
digitizing an image, detecting a feature and then computing a
measure of the feature. Several image analysis systems which
are capable of performing these three functions are commercially
available from Buehler, Ltd. (OMNIMET); Bausch and Lomb (OMINICON)
Alpha, OMINICON PAS and OMINICON FAS-l 1 ); Cambridge Instruments,
Inc. (QUANTIMET 720/23C, 720/25C and 800) and Leitz ~T.A.S. ) .
All of these systems are based on video camera image scanning
techniques. In order to be sure that the video signal accurately
represents the image received, special characteristics are
necessary in the cameras employed and such cameras are either
specially designed or specially selected for accuracy of scanning.
Several video tubes are available for image analysis, and the most
common are known as the VIDICON, PLUMBICON, CHAHLNICON and SILICON
VIDICON.
Down-Hole Investiqation
As previously indicated, the optical examination input can
also be derived from a probe inserted into the well bore itself
either through a drill string or into a bore not having drilling
equipment therein.
A tool which is particularly usable in the absence of drill
string, as during tripping, is shown in ~igs. 10 and 11, Fig. 10
5howing the tool mounted on a section of drill string 160 having
rather conventional calipers with arms 161 mounted to the string
.~ f~QO/~ k~
-32-
.
: ~ o
by conventional mounting devices 16l and 163 which can include
tension springs with anyle transducers. Normally, four arms
161 would be provided, three of the arms having idle rollers
164 and the fourth arm having an optical foot 165 which is
shown in greater detail in Fig. 11. A cable 166 extends through
the interior of string 160, the cable including optical fibers
and electrical wires, various ones of the wires being connected
to the angle transducers and to a tool attitude package 168
for providing a continuous reading of the attitude of the
tool as other readings are made. A portion of the cable 169
containing the optical fibRrs and at least two electrical
conductors is connected to foot 165. As will be recognized,
rollers 164 maintain contact with the walls of the bore hole
170, causing the outer surface of foot 165 to ride against
one side of the bore hole wall.
Although not illustrated in Fig. 10, it will be recognized
that one or more of the rollers can be replaced by an optical
foot so that simultaneous investigation of circularly spaced por-
tions of the bore hole wall can be accomplised at the same time,
permitting additional information to be derived about the dip
of ~ormations penetrated by the bore hole.
The optical foot itself, as shown in Fig. 11, includes a
body 171 having a cavity 172 to receive the ends of the various
components of the cable. The cable itself is provided with a
termination having flanges 173 bolted or otherwise attached to
a threaded gland 174 to maintain the cable in a sealing relation-
ship with the foot. As seen in Fig. 11, the cable itself includes
a tube or hose 176 which terminates in a nozzle 177 directed to-
ward an opening 178 in the side of the foot adjacent the bore hole
wall. At the bottom portion of the foot, a portion of the opening
is spaced away from the bore hole wall, leaving a gap 179 through
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.
073
which fluid can flow out of the foot cavity. The purposeof the fluid is to provide an optically clear solution within
the foot cavity, and adjacent to the bore hole wall, permitting
optical examination thereof. To facilitate the cleaning action,
an ultrasonic transducer 180 is disposed in cavity 172 with its
transducer being oriented so that ultrasonic energy is transmitted
toward the portion of the bore hole wall encompassed by opening
178. A relatively low energy level of ultrasonic energy, such
as that producible by a conventional piezoelectric device, tends
to loosen material, such as mud cake, adjacent the bore hole wall,
which material is then flushed away by the fluid passing through
conduit 176. Transducer 180 is energized by power supplied through
electrical conductors 181.
At least two optical fibers 182 and 183 are included in the
cable and terminate at connectors having objectives 184 and 1~5,
respectively, disposed in cavity 172 facing the portion of the
bore hole wall encompassed by opening 178.` One of the fibers such
as, for example, fiber 182, is a source fiber and provides illumina-
tion at a preselected wave length or band of wave lengths from a
source at the earth's surface to illuminate, through the fluid
supplied by conduit 176, the surface of the bore hole wall. Light
reflected from that surface is received through objective 185 by
fiber 183 and conducted to the surface. Although not illustrated
in Fig. 11, the foot can be sufficiently large to accomodate a
number of source and receiving fibers, providing a variety of images
and providing the possibility for illumination at more than one
wave length. The ultrasonic transducer, ob~ectives and fluid
conduit can be supported in a generally hemispheral shell 187 for
mechanical mounting of these components in fixed relationship with
each other.
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~ 174073
In use, the tool can be lowered, during tripping, to the
bottom of the hole and then more slowly elevated to the surface,
continually providing optical image data which is easily corre-
latable with depth information and attitude information supplied
by package 168. The caliper structure maintains the optical
foot in close proximity with the bore hole wall while viewing
is accomplished through the fluid supplied. It should also be
recognized that the information derived from this structure can
be in the form of an image viewable by an individual having a
microscope coupled to the optical fibers at the surface so that
a geologist at the surface can directly look at the exposed
surface portions of subsurface formations. It will also be
recognized that various enhancement techniques can be employed
to improve the obtained image.
It is important to recognize that the apparatus shown in
Figs. 10 and 11 can advantageously be employed in sequence with
the mud analysis system described herein. Assume, for example,
that a well is in the process of being drilled and the chips,
sand, etc. brought to the surface by drill mud return is contin-
ually being analyzed and that, at some stage, the displays indicate
the likelihood that an interesting, developable formation may have
been penetrated by the drill bit. The apparatus shown in Figs. 10
and 11 can then be employed, during the next trip, to visually
inspect the walls of the bore hole which was recently penetrated
to either confirm or reverse the indication given by the mud
return analysis techniques. This sequential use of the devices
provides far more input than is ordinarily available, and pro-
vides the geologist with a much more reliable indication of
a formation which may be a very thin stratum of a type which is
commonly overlooked in the traditional techniques.
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~174073
It will also be recognized that an indication of the drill
having entered a region known to normally accompany a developable
formation may occur at a time when tripping of the string is not
about to occur. In this case, it may be desirable to optically
inspect the bottom of the bore hole without extracting the string
and drill. An apparatus such as that shown in Figs. 12 and 13 can
be employed in these circumstances.
A side elevation of one form of typical drilling bit is
partially shown in Fig. 12, the bit being of the type having a
body 190 and an externally threaded connector portion 191 which
would normally be connected to the lower end of the drill string,
not shown. The body carries three conical bit cones 1g2, only
one of which is shown in the figure. A mud conduit 193 is formed
in the body to permit the flow of mud to the vicinity of the bit
to remove cuttings therefrom and flush the bottom of the hole, the
mud then flowing up the annulus around the drill string. As will
be recognized by those skilled in the art, various configurations
of bits are commonly employed, but many such bits contain mud
conduits in different configurations, and an apparatus can be
provided to conform to the location of such conduits for optical
investigation. Figs. 12 and 13 show a device 194 which can be
used for this purpose with the bit shown, the device being sus-
pended on a cable 195 which supports the device and also contains
optical and electrical conductors for the investigation. When it
is desired to use the device, the drilling operation is stopped
and the device is lowered through the drill string, the lowering
being assisted by mud pumping, causing the device to act as a
piston passing through the drill string. Centering arms 199
maintain the device in a centered position, and lowering is
StOpped when a sensing plunger 196 encounters the inner lower
surface of the bit.
. I -
; ~ -36-
0 7 3
It will be recognized that conduits 193 are equally spaced
120- apart so that they cooperate to flush the three bit cones pro-
vided. Device 194 is provided with a spring urged plunger 197 which
extends outwardly and downwardly and is shaped to enter one of the
conduits. Cable 195 is rotated to cause slow rotation of device
194 until plunger 197 enters one of the conduits. This positions
the device so that a probe 198 protruding from device 194 points
directly at another one of the conduits 193. The probe, connected
to an optical fiber cable within the device, can then be extended,
as by hydraulic pressure or an electrical device, causing the probe
to extend into conduit 193 and to the outer surface of the bit until
the outer portion of the probe is adjacent the bore hole wall. An
optically clear fluid can then be pumped through the prober clearing
the portion of the bore hole wall adjacent the end of the probe,
permitting optical inspection of the wall adjacent bit. Whlle the
area of the borehole wall examined by the probe in this fashion
is somewhat smaller than that usable with the device of Figs~ 10
and 11, useful information can nevertheless be derived.
Fig. 13 shows a bottom plan view of the device, illustrating
the angular relationships of the locating plunger 197 and probe 198.
After use, the device can simply be extracted from the bit and string,
and returned to the surface.
The devices of Figs. 10 and 11 or 12 and 13 can be used in
place of the optical assemblies 121a-y shown in Fig. 9 to transmit
light through the fibers of cable 163 and window 161 to the surface
of a borehole 170 to be examined. A sequence of different wave
lengths of light is supplied to selected ones of the fibers in the
cable and reflected or luminescent light from the borehole wall -
is returned to the fibers and conducted up the hole to the multi-
plexing and yroces-ing equipment at the sorEace as sho~n In Fig. 9.
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The surface of borehole 170 is normally smoothed to a considerable
degree by the action of the drill which formed the hole, preparing
the mineral surface for examination so that further grinding or the
like is not necessary.
It has been recognized that optical fibers exhibit unique
attenuation characteristics and that the transmission efficiency
characteristics are a nonlinear function of wavelength. When
the fibers are used only for information transmission, as by
pulse or otherwise modulated light, the power levels are rather
low and the losses, while significant and in some cases annoying,
can be tolerated. ~owever, by properly choosing fiber type and
light wavelengths, efficiencies of between 40~ and 90% or better
can be obtained. This is particularly important when long runs
of fibers such as in cable 163 are involved, and when low reflec-
tance levels of light received through window 161 are to be trans-
mitted directly to the surface. This also becomes critically
important in conveying large power levels along long fiber cables.
Fig 14 is a simplified graphical representation of the trans-
mission characteristics of two types of fibers, the upper curve G
being that of a Corning graded index glass fiber and the lower
..
curve S being that of a step index fiber produced by Quartz Products
Company. The vertical axis is percent transmission per kilometer
and the horizontal axis is wavelength. As will be seen, the graded
index fiber transmission efficiency exceeds 40~ toward the red end
of the spectrum (yellow-orange region of visible light) and increases
with increasing wavelength into the infrared and far infrared region,
somewhat beyond the visible range. Light in the visible and infrared
regions are particularly useful in optical analysis of minerals.
rad~7 o r k
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Hence, fibers of either type can be used with appropriate selection
of sources, the choice being made partly on the basis of cost and
reco~nizing that, at the present time, graded index fibers are more
expensive than step index.
Figs. 15A-C, taken together, constitute a flow diagram of the
information delivered to, used in, and provided by the geological
data bases discussed above. As will be seen, the inputs, which are
derived from the optical and digital analyses, involve identification
and classification of chips and grains (sand, silt and clays) with
identification of the spatial relationships of the mineral grains
comprising the chips. Because rather large numbers of chips and grains
are viewed by the optical portions of the system, the analysis and
classification may be a statistical one rather than being a "single"
chip or grain analysis, and this input therefore in terms of per-
centages of characteristics observed. In the composition analysis,
mineralogical and chemical compositions from diffraction data and
chromatographic analysis may be similarly statistical except for the
identification of hydrocarbons present in either gases or liquids.
Fossil identification is also direct, although a statistical
approach can be used and would be in certain types of formations.
It should also be noted that fossil identification by pattern recogni-
tion is a useful approach to provide this information, using the
apparatus of Figs. 4-8 or 10-13. Assemblages of fossils provide
useful information. Finally, the depths from which the specimens
were recovered, or are being observed, along with pressures and other
drilling parameters are supplied.
These data inputs are supplied to the ~.DB core which, as
previously indicated, takes the forms of an exploration GDB or a
development GDB. While there is not an absolute line of demarca-
tion between these types, and recognizing that an exploration GDB
will evolve into a development GDB as information is accumulated
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and stored, the emphasis in exploration is on determining the
envlronment of the deposit from or in which materials are
examined, the age of each formation, the position in a basin
and the possibility of hydrocarbon accumulation as evidenced
by the input factors.
In a development of a basin about which much is already
known and stored from data bases such as the ones previously
mentioned, the emphasis is placed on lithostratigraphic correla-
tion and biostratigraphic correlation with the known basin
characteristics, along with recognition and correlation of the
presence and type of hydrocarbons present. Furthermore, the
relative positions, attitudes, thicknesses and ages of specimens
and strata encountered in a borehole being formed aid in the
placement of that hole in the spatial context of the overall
field and permit accurate prediction of the presence o~ forma-
tions of interest, as well as enhancing the lnformation previ-
ously known.
It is ~hus possible to provide outputs, from the explora-
tion GDB analysis, of various parameters for every depth increment
including lithologic features, presence and types of hydrocarbons
found, an estimate of the biostratigraphic age with good accuracy,
and other formation features including the physical parameters
such as formation velocity Vf-m~ the position in the basin, the
environment of the deposition and the potential for the existence
of hydrocarbons.
These outputs are, and should be, regarded as estimated
values in an exploration GDB but are in themselves highly useful.
In addition, as these values are supplied to and correlated with
known sections in the basin in a development GDB, it is possible
to extract more specific information such as the geolo~ic age of
each formation, the formation name, the member name and the bed
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description including a refined prediction of the potential for
hydroc~rbon deposits, bed thickness and its rclative position in
the basin. Knowing these, one can arrive at speciic stratigraphic
- correlations including the actual thickness of the overlying section,
the predicted relation of the bed to the underlying section and a
horizontal prediction of the formation characteristics.
It will be readily apparent that this information is excellent
guidance for -controlling the drilling operation and permits
most efficient use of the drilling equipment and manpower available
Furthermore, continually updated information adds greatly to the
safety of the drilling operation since evidence of approaching dif-
ficult or dangerous conditions, such as increasing downhole pressure,
are brought to the drilling supervisor's attention promptly.
Still further, the information stored in a development GDB
permits the generation of any of a variety of "multi dimensional"
displays since the stored data includes spatial data for a large
number of subsurface points. Such a display can be generated in
a CRT or hard copy form using conventional contour graphic mapping
routines such as those emplo~ed by Data Plotting Service, Don Mills,
Ontario, Canada, which software is also available from IBM Corp.
and Control Data Corp. as plotting packages. The displays have
the obvious advantage of permitting visualization of a region
under investigation.
While certain advantageous embodiments have been chosen to
illustrate the invention it will be understood by those skilled in
the art that various changes and modifications can be made therein
without departing from the scope of the invention as defined in
the appended claims.
- . . , ~,
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.. ~ ,. .
