Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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OBTAINING A DOWNHOLE CORE SAMPLE MEASUREMENT USING
LOGGING WHILE CORING
TECHNICAL FIELD
The present disclosure relates generally to coring operations of downhole
drilling and, more particularly, to a drilling tool and method for obtaining a
downhole
core sample measurement using logging while coring.
BACKGROUND
Conventional logging techniques, such as wireline and logging while drilling
(LWD), employ tools that use dedicated sensors to collect data from the
surrounding
formation of a wellbore. The signal between the transmitters and receivers
passes
through a very complicated and open environment that is susceptible to noise,
multipath propagation, washout, mud cake, and invasion problems. These
borehole
conditions add tremendously to the cost and complexity of the tool, and affect
its
reading accuracy. Along with the inherent geometrical layout of the tool, this
puts a
limit on the class of measurements/sensors that can be used, the data
acquisition
resolution, and the direction of measurement
Conventional tools for obtaining a core from the bitface at the end of a
wellbore usc dedicated coring drill bits to collect cylindrical core samples.
Core
samples are subsequently inspected and analyzed at the surface by various
equipment
and techniques depending on the type of information to be collected. For
example,
core samples can provide indications of formation properties such as porosity,
permeability, and other physical or pctrophysical properties of the downhole
formation.
In typical operations, a coring drill bit may be used to collect a continuous
core sample at the bitface during the drilling operation. Multiple core
samples may be
collected and stored in proximity to the coring drill bit. After collection of
the desired
number of samples, the core samples are lifted to the surface to measure
properties of
the samples. Most laboratories extract only small plugs from the core samples
and
provide a relatively small number of data points across the whole well.
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The core samples, however, can be damaged or compromised in the process of
lifting the core samples to the surface. Thus, conventional systems typically
include
components to support and protect the core sample while lifting it to the
surface.
Contact between drilling fluids and the core sample may compromise later
measurements made to the core sample. Furthermore, mechanical forces during
removal and lifting of the core sample may cause the core sample to fracture,
which
may complicate the ability to gather information from the core sample. Core
samples
can further degrade when they are transported to a laboratory, or otherwise
handled to
study. Incorrect or inconsistent values from core samples may have severe
implications for wellbore drilling operations.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present disclosure and its features
and advantages, reference is now made to the following description, taken in
conjunction with the accompanying drawings, in which:
FIGURE 1 illustrates a schematic diagram of a drilling apparatus for a logging
while drilling or a coring tool in a wellbore, in accordance with some
embodiments of
the present disclosure;
FIGURE 2 illustrates a perspective view of a coring bit assembly, in
accordance with some embodiments of the present disclosure;
FIGURE 3 illustrates a perspective view of coring bit electronics associated
with a coring bit assembly for performing measurements transversely across a
core
sample, in accordance with some embodiments of the present disclosure;
FIGURE 4 illustrates a cross-sectional view of the coring bit electronics in
the
coring bit assembly of FIGURE 3 for performing measurements transversely
across a
core sample, in accordance with some embodiments of the present disclosure;
FIGURE 5 illustrates a cross-sectional view of coring bit electronics in a
coring bit assembly for performing measurements to detect anisotropic
properties
across a core sample, in accordance with some embodiments of the present
disclosure;
FIGURE 6 illustrates a perspective view of coring bit electronics in a coring
bit assembly for performing measurements transversely and longitudinally
across a
core sample, in accordance with some embodiments of the present disclosure;
and
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FIGURE 7 illustrates a flow chart of an example method for performing
measurements on a core sample during LWC operation with coring bit
electronics, in
accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION
Embodiments of the present disclosure and its advantages are best understood
by referring to FIGURES 1-7, where like numbers are used to indicate like and
corresponding parts.
FIGURE 1 illustrates a schematic diagram of a drilling apparatus 100 for a
logging while drilling or a coring tool in wellbore 106, in accordance with
some
embodiments of the present disclosure. Drilling tool 116 may be suspended by
drill
pipe 104 in wellbore 106 defined by sidewall 108.
Drill pipe 104 may include one or more electrical conductors and a multi-
strand cable. Drill pipe 104 may include an armored logging cable and may
encompassing the cables and conductors. In some embodiments, drill pipe 104
may
include drilling tool 116 and may be extended into wellbore 106.
In some embodiments, drilling tool 116 may include any device or
combination of devices suitable for drilling wellbore 106 and/or extracting
core
samples from wellbore 106. Drilling tool 116 may rotate by the operation of
drill pipe
104 to extract a core sample or drill into wellbore 106.
In some embodiments, logging while drilling (LWD) may include drilling into
the earth and recording information from sensors 120 that may be located
proximate
the exterior of drilling tool 116 above the drill bit or coring bit 102 to
produce a
record of various formation parameters. In such configurations, drilling tool
116 may
include coring bit assembly 126, drill collar 118, sensors 120, other on-board
electronics, telemetry systems, pressure compensators, hydraulic fluid
systems, and/or
any other suitable devices. Drill collar 118 and sensors 120 may be located
above
coring bit 102 with respect to drill pipe 104. Drill collar 118 may include
electronics
that measure sensor 120 outputs and store them as a function of time or
transmit them
to a surface control unit and/or any other suitable compute. Sensors 120 may
provide
continuous measurements of downhole parameters, such as, porosity,
resistivity,
formation pressure, and/or any other suitable measurements. Sensors 120 may be
located on the exterior of drilling tool 116 and may be configured to detect
downhole
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parameters as drilling tool 116 descends and/or drills into wellbore 106.
However,
due to the location of sensors 120, e.g., above coring bit 102 with reference
to drill
pipe 104, sensors 120 may provide indirect measurements of the current
formation
being drilled and may be affected by the downhole environment. For example,
sensors 120 may be exposed to mud as mud flows past drilling tool 116.
Accuracy of
sensors 120 may additionally be affected by standoff between drilling tool 116
and
sidewall 108. Further, the direction of sensors 120 with respect to sidewall
108 may
be oriented such that the direction may also affect accuracy of measurements.
In some embodiments, alternate configurations of drilling apparatus 100 may
be arranged for Logging While Coring (LWC) operations. LWC may include
extracting a core sample and detecting and/or recording information from
sensors that
may be located proximate to the interior of drilling tool 116. In such
embodiments,
LWC may include taking, e.g. logging, measurements of a core sample as the
core
sample is passing through drilling tool 116. In LWC operation, coring bit
assembly
126 (shown in further detail in FIGURE 2) may include coring bit 102 and may
operate to extract a core sample from wellbore 106. In some embodiments,
coring bit
assembly 126 may also include sensors, calipers, electronics, transmitters,
receivers,
and other elements to perform in-situ measurements of a core sample. As
discussed
below, the measurements may be transmitted to a surface control unit, drill
collar 118,
and/or other suitable devices for further analysis. The sensors may
continuously
collect data from a moving string of cores in critical spots of the well. LWC
operation may improve measurement accuracy and resolution, add anisotropic
capabilities, and introduce new classes of measurements that may not be
achievable
with LWD operation.
FIGURE 2 illustrates a perspective view of coring bit assembly 126, in
accordance with some embodiments of the present disclosure. Coring bit 102 may
be
any of various types of fixed cutter drill bits, including polycrystalline
diamond cutter
(PDC) bits, drag bits, matrix drill bits, and/or steel body drill bits
operable to extract a
core sample from wellbore 106. Coring bit 102 may be designed and formed in
accordance with teachings of the present disclosure and may have many
different
designs, configurations, and/or dimensions according to the particular
application of
coring bit 102.
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Coring bit body 306 may have a generally cylindrical body and inner gage
314. Coring bit 102 may further include throat 310 that may extend
longitudinally
through coring bit 102. Throat 310 of coring bit 102 may allow a core sample
to be
cut with a smaller diameter than throat 310. Coring bit 102 may include one or
more
5 cutting
elements 302 disposed outwardly from exterior portions of bit body 306. For
example, a portion of cutting element 302 may be directly or indirectly
coupled to an
exterior portion of bit body 306 while another portion of cutting element 302
may be
projected away from the exterior portion of bit body 306. Cutting elements 302
may
be any suitable device configured to cut into a formation, including but not
limited to,
primary cutting elements, back-up cutting elements, secondary cutting elements
or
any combination thereof. By way of example and not limitation, cutting
elements 302
may be various types of cutters, compacts, buttons, inserts, and gage cutters
satisfactory for use with a wide variety of coring bits 102.
Cutting elements 302 may include respective substrates with a layer of hard
cutting material disposed on one end of each respective substrate. The hard
layer of
cutting elements 302 may provide a cutting surface that may engage adjacent
portions
of wellbore 106. Each substrate of cutting elements 202 may have various
configurations and may be formed from tungsten carbide or other materials
associated
with forming cutting elements for coring bits. Tungsten carbides may include,
but are
not limited to, monotungsten carbide (WC), ditungsten carbide (W2C),
macrocrystalline tungsten carbide and cemented or sintered tungsten carbide.
Substrates may also be formed using other hard materials, which may include
various
metal alloys and cements such as metal borides, metal carbides, metal oxides
and
metal nitrides. For some applications, the hard cutting layer may be formed
from
substantially the same materials as the substrate. In other applications, the
hard
cutting layer may be formed from different materials than the substrate.
Examples of
materials used to form hard cutting layers may include polycrystalline diamond
materials, including synthetic polycrystalline diamonds.
In operation of embodiments of the present disclosure, coring bit 102 may
extract a core sample from a formation of interest approximately the diameter
of
throat 310. As discussed in detail below, sensors, calipers, electronics, and
other
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elements resident in coring bit assembly 126 may make in-situ measurements of
the
core sample.
Coring bit 102 may be connected to coring mandrel 402. Coring mandrel 402
may have a longitudinal opening 404 that may correspond to throat 310. One end
of
coring mandrel 402 may be threadably connected to threaded form 406. Inner
barrel
408 may pass through coring mandrel 402 and/or threaded form 406. Further,
inner
barrel 408 may contain inner sleeve 410 that may capture core sample 412.
Inner
sleeve 410 may be encompassed by inner barrel 408 and/or may extend beyond
inner
barrel 408. Threaded form 406 may connect inner barrel 408 to coring bit 102
via
coring mandrel 402.
Additionally, in some embodiments of the present disclosure coring bit
electronics 414 may be contained in coring mandrel 402. Coring bit electronics
414
may also be located in inner barrel 408 (not expressly shown), inner sleeve
410 (not
expressly shown), and/or any combination of coring mandrel 402, inner barrel
408,
and inner sleeve 410, and/or any other suitable location. Coring bit
electronics 414
may include any receivers, transmitters, transceivers, sensors, calipers,
and/or other
electronic components that may be used in a downhole measurement system.
Sensors
may include multiple types, including but not limited to, resistivity,
dielectric, sonic,
nuclear, or nuclear magnetic resonance (NMR). Coring bit electronics 414 may
also
include any necessary electronics to provide communication between the
receivers,
transmitters, transceivers, sensors, calipers, and/or other electronic
components. The
spacing, exact location, and transmitter-receiver arrangement of coring bit
electronics
414 may depend on factors including, but not limited to, the direction of
measurement
and/or the type of sensors, calipers, and/or other types of measurement tools.
Implanting coring bit electronics 414 in coring mandrel 402, inner barrel 408,
inner sleeve 410, and/or any other suitable location may allow coring bit
electronics
414 to perform direct and/or continuous measurements as core sample 412 moves
through coring bit assembly 126. Accordingly, some embodiments of the present
disclosure may allow measurements of core sample 412 to be made in drilling
tool
116 (as shown with reference to FIGURE 1). Following extraction from wellbore
106, core sample 412 may be stored and later retrieved and lifted to the
surface. Core
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sample 412 may be lifted to the surface by retrieving inner sleeve 410 and/or
by
extraction of drilling tool 116 from wellbore 106.
During LWD operation, contamination may affect measurements made by
sensors 120 due to characteristics of the wellbore environment, including tool
standoff, washouts, mud flows and/or other situations that may compromise
measurement integrity of sensors 120. Similar conditions may apply during
wireline
operations, which may include lowering sensors into a wellbore after removal
of a
drilling tool. However, during LWC operation the measurements made by coring
bit
electronics 414 of a core sample may not be affected by such wellbore
situations.
Measurements by coring bit electronics 414 may have the advantage of a
measurement environment confined around core sample 412 being relatively
small.
The distance between multiple sensors ancUor other elements may also be
relatively
small in the confined environment of coring bit assembly 126. Noise and multi-
path
effects that may be present in the wellbore and may affect measurements made
by
sensors 120 may not be present around coring bit electronics 414 during LWC
operation. Therefore, coring bit electronics 414 may be simpler in
configuration and
design than sensors 120. For example, the confined space may minimize the
transverse movement of core sample 412 in coring mandrel 402, inner barrel
408,
and/or inner sleeve 410 allowing for less eccentricity related impact and more
consistent measurements. Additionally, the power requirements for coring bit
electronics 414 may be less than the power requirements for sensors 120.
Further, as
discussed in detail below with reference to FIGURES 5 and 6, LWC operation
utilizing coring bit electronics 414 may include measuring parameters of core
sample
412 in multiple directions, e.g., x-axis, y-axis, and z-axis.
Resolution of
measurements may also be improved since resolution may be a function of the
distance between sensors. LWC operation utilizing coring bit electronics 414
may
provide a minimum distance between a transmitter and a receiver, and thus, may
provide enhancements to resolution than may be achieved with LWD.
Additionally, when compared with the conventional logging methods (e.g.,
wireline and LWD), LWC may provide real-time formation measurements that may
have better correlation with the core laboratories measurements. LWC may
further
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overcome issues regarding core porosity and mechanical properties that may
occur
after a core sample is removed from the wellbore to a laboratory for
measurement.
The LWC tool may be operated as the sole logging tool or in conjunction with
other logging techniques. This may be done in order to obtain increasingly
accurate,
high-resolution and anisotropic data in the critical spots of the wellbore.
The
collected data may also be used to calibrate readings from LWD or wireline
sensors
outside the cored range to enhance their accuracy without the need to wait for
laboratory data.
FIGURE 3 illustrates a perspective view of the coring bit electronics in a
coring bit assembly for performing measurements transversely across a core
sample,
in accordance with some embodiments of the present disclosure. In the
illustrated
embodiment, a portion of coring mandrel 402 containing a portion of core
sample 412
is shown. Coring mandrel 402, inner barrel 408, inner sleeve 410 (shown in
FIGURE
2), and/or any other suitable location may include coring bit electronics 414.
Coring
bit electronics 414 may include transmitter 502, receiver 504, sensors,
calipers, and/or
other electronics or elements suitable for measurement of core sample 412.
This
configuration may allow the measurement of properties across core sample 412
in the
transverse direction, e.g., the x-axis direction. Additionally, some
embodiments of
the present disclosure may include receiver 504 without transmitter 502.
In some embodiments, during LWC operation, coring bit 102 may extract core
sample 412 from the formation. Core sample 412 may be captured by inner sleeve
410 and pass through inner barrel 408. As the core sample 412 passes through
inner
barrel 408, coring bit electronics in coring mandrel 402 may make measurements
of
various characteristics and properties of core sample 412, for example. The
measurements may be taken continuously as core sample 412 passes through
coring
bit assembly, and/or the measurements may be interval based and may be
programmed to take a measurement based on either elapsed time and/or length of
core
sample 412. Additionally, the measurements may be taken as needed based on a
pre-
defined measurement protocol.
In some embodiments, measurements made by coring bit electronics 414 may
be communicated to a surface control unit and/or any other suitable unit for
receiving
signals from coring bit electronics 414. Logs may be created using information
from
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coring bit electronics 414 and the logs may exhibit improved accuracy than
would be
achieved by sensors 120 or achieved airier core sample 412 is removed to the
surface.
Further, additional classes of measurements, e.g., computed tomography and/or
other
scanning techniques may be available to coring bit assembly 126, in accordance
with
some embodiments of the present disclosure.
FIGURE 4 illustrates a cross-sectional view of coring bit electronics 414 in
coring bit assembly 126 of FIGURE 3 for performing measurements transversely
across a core sample, in accordance with some embodiments of the present
disclosure.
Transmitter 502 and/or receiver 504 may be mounted within or attached to
coring
mandrel 402. Although the present embodiment is illustrated with respect to
coring
mandrel 402, transmitter 502 and/or receiver 504 may also and/or alternatively
be
mounted within or attached to inner barrel 408, inner sleeve 410, and/or
mounted in
any suitable location. Transmitter 502 may be located substantially opposite
from
receiver 504 with respect to core sample 412. Sensors, calipers, and/or other
measurement tools may be included as part of or near to transmitters 502
and/or
receivers 504. Further, transmitter 502 and/or receiver 504 may be
transceivers in
order to transmit and receive from both sides of coring mandrel 402, inner
barrel 408,
and/or inner sleeve 410. In operation of embodiments of the present
disclosure, a
signal may be sent from transmitter 502 and received by receiver 504. The
characteristics and properties of the signal received by receiver 504 may
indicate
various properties of core sample 412, e.g., porosity, permeability, and other
physical
or petrophysical properties of core sample 412. The resultant signals and/or
measurements may be communicated to a surface control unit via any suitable
method
for communicating data.
FIGURE 5 illustrates a cross-sectional view of coring bit electronics 414 in
coring bit assembly 126 for performing measurements to detect anisotropic
properties
across core sample 412, in accordance with some embodiments of the present
disclosure. In the illustrated embodiment, coring bit electronics 414 may
contain two
transmitters 502a and 502b and two receivers 504a and 504b. Transmitter 502a
may
be arranged substantially opposite from receiver 504a with respect to core
sample
412, e.g., along the x-axis. Likewise, transmitter 502a may be arranged
substantially
opposite from receiver 504b with respect to core sample 412 and approximately
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ninety degrees rotated from transmitter 502a and receiver 504a, e.g., along
the y-axis.
Sensors, calipers, and/or other measurement tools may be included as part of
or near
to transmitters 502 and/or receivers 504. Further, transmitters 502 and/or
receivers
504 may be transceivers in order to transmit and receive from both sides of
coring
5 mandrel 402 and/or inner barrel 408. In operation of embodiments of the
present
disclosure, a signal may be sent from transmitter 502a and received by
receiver 504a.
Additionally, a signal may be sent from transmitter 502b and received by
receiver
504b. The characteristics and properties of the signal received by receivers
404 may
indicate various properties of core sample 412, e.g., porosity, permeability,
and/or
10 other physical or petrophysical properties of core sample 412. The
resultant signals
and/or measurements may be communicated to a surface control unit via any
suitable
method for communicating data. The configuration shown in FIGURE 5 may allow
the detection of anisotropic properties in core sample 412 (e.g., detection of
unequal
physical properties along different axes) by measuring core sample 412
properties in
both the x-axis and y-axis directions.
FIGURE 6 illustrates a perspective view for coring bit electronics 414 in
coring bit assembly 126 for performing measurements transversely and
longitudinally
across core sample 412, in accordance with some embodiments of the present
disclosure. Transmitters 502 and/or receivers 504 may be mounted within or
attached
to coring mandrel 402. Although the present embodiment is illustrated with
respect to
coring mandrel 402, transmitters 502 and/or receivers 504 may also and/or
alternatively be mounted within or attached to inner barrel 408, inner sleeve
410,
and/or mounted in any suitable location. In the illustrated embodiment, coring
bit
electronics 414 may include two receivers 504a and 504b and transmitter 502a.
Transmitter 502a may be arranged substantially opposite from receiver 504a
with
respect to core sample 412, e.g., along the x-axis. Receiver 504b may be
arranged
axially with transmitter 502b, e.g., along the z-axis. Sensors, calipers,
and/or other
measurement tools may be included as part of or near to transmitter 502a
and/or
receivers 504a and 504b. Further, transmitter 502a and/or receivers 504a and
504b
may be transceivers in order to transmit and receive from both sides of coring
mandrel
402, inner barrel 408, ancUor inner sleeve 410. In operation of embodiments of
the
present disclosure, a signal may be sent from transmitter 502a and received by
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receiver 504a and/or receiver 504b. The characteristics and properties of the
signal
received by receivers 504 may indicate various properties of core sample 412,
e.g.,
porosity, permeability, and/or other physical or petrophysical properties of
core
sample 412. The resultant signals and/or measurements may be communicated to a
surface control unit via any suitable method for communicating data. The
configuration shown in FIGURE 6 may allow both transverse measurement (e.g.,
between transmitter 502a and receiver 504a) and longitudinal measurement
(e.g.,
between transmitter 502a and receiver 504b).
As exemplified by FIGURES 2-6, many arrangements may exist for coring bit
electronics 414 to enable different types of measurements of core sample 412.
Other
suitable configurations of components may be used as part of the coring bit
electronics without departing from the scope of the present disclosure. For
example,
coring bit electronics 414 may include more or fewer components, including
transmitters 502 and receivers 504, than shown in FIGURES 2-6. As another
example, coring bit electronics 414 may allow for measurements based on
electromagnetic radiation or a light spectrum, such as visible light, infra-
red,
ultraviolet, and/or x-ray. In designing a configuration in embodiments of the
present
disclosure, consideration may be made of the type of components, placement of
components, corrections for polarization of transmitted waves, and other
considerations. For example, continuity of the core string may become a
challenge
that may be corrected by the addition of an internal mechanical or electronic
caliper to
the coring bit electronics.
FIGURE 7 illustrates a flow chart of example method 700 for performing
measurements on core sample 412 during LWC operation with coring bit
electronics
(e.g., 414 of FIGURES 2-6), in accordance with some embodiments of the present
disclosure. The steps of method 700 may be performed by various computer
programs, models or any combination thereof, configured to operate a drilling
tool,
perform measurements, and log/analyze results. The programs and models may
include instructions stored on a computer readable medium and operable to
perform,
when executed, one or more of the steps described below. The computer readable
media may include any system, apparatus or device configured to store and
retrieve
programs or instructions such as a hard disk drive, a compact disc, flash
memory or
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any other suitable device. The programs and models may be configured to direct
a
processor or other suitable unit to retrieve and execute the instructions from
the
computer readable media. Collectively, the computer programs and models used
to
operate a drilling tool, perform measurements, and log/analyze results may be
referred
to as a "drilling engineering tool" or "engineering tool." For illustrative
purposes,
method 700 is described with respect to drilling tool 116 of FIGURE 1;
however,
method 700 may be used to perform measurements, and log/analyze results using
any
suitable drilling tool.
Method 700 may start and at step 706, the engineering tool may direct a
drilling tool to extract a core sample from a wellbore. For example, coring
bit 102
may be directed to operate and cut core sample 412 from wellbore 106. Once
core
sample 412 has been extracted from wellbore 106, method 700 may continue to
step
708.
At step 708, the engineering tool may direct the coring bit assembly to obtain
measurements of the core sample using the coring bit electronics and log
results. For
example, coring bit electronics 414 contained in coring bit assembly 126 may
perform
transverse measurements using transmitter 502 and/or receiver 504. The
measurements may be transmitted to a surface control unit and logged and/or
analyzed.
At step 710, the engineering tool may determine if all measurements have
been successfully captured and logged. If more measurements are required,
method
700 may return to step 708 to perform additional measurements. If no
additional
measurements are required, method 700 may proceed to step 712.
At step 712, the engineering tool may direct the drilling tool to remove the
core sample. For example, core sample 412 may be removed to the surface or
core
sample 412 may be deposited into a storage compartment for later removal. For
example, drilling tool 116 may deposit core sample 412 in a storage tube (not
shown).
At step 714, the engineering tool may determine if more core samples are
required. If more core samples are required, method 700 may return to step
706. For
example, if more measurements are required, another core sample 412 may be
obtained from wellbore 106. This cycle may be repeated until all of core
samples 412
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are collected, after which, at step 716 drilling tool 116 may be removed from
wellbore
106. Following removal of drilling tool 116, method 700 may end.
Modifications, additions, or omissions may be made to method 700 without
departing from the scope of the present disclosure. For example, the order of
the
steps may be performed in a different manner than that described and some
steps may
be performed at the same time. Additionally, each individual step may include
additional steps without departing from the scope of the present disclosure.
Although the present disclosure and its advantages have been described in
detail, it should be understood that various changes, substitutions and
alternations can
be made herein without departing from the scope of the disclosure as defined
by the
following claims.
