U.S. patent application number 14/454935 was filed with the patent office on 2015-12-17 for gamma probe health detection assembly.
This patent application is currently assigned to REME TECHNOLOGIES, LLC. The applicant listed for this patent is REME TECHNOLOGIES, LLC. Invention is credited to JOSHUA CARTER, ABRAHAM ERDOS, DAVID ERDOS, JAMES MATHIESON, KENNETH MILLER.
Application Number | 20150362599 14/454935 |
Document ID | / |
Family ID | 51702287 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150362599 |
Kind Code |
A1 |
MILLER; KENNETH ; et
al. |
December 17, 2015 |
GAMMA PROBE HEALTH DETECTION ASSEMBLY
Abstract
An improved gamma controller health detection assembly to
facilitate reliable downhole measurement of naturally occurring
radiation is disclosed. The gamma controller assembly includes one
or more gamma sensors, a micro-controller, memory, and input/output
ports among other components. The gamma sensors detect radiation
and output pulses that are received by the microcontroller. The
sensor data can be checked, selected, and averaged by the
microcontroller, and sent uphole to another microcontroller or
computer that can then further process, communicate, and display
the data. The sensor data can be averaged and stored to memory or
stored as independent values to memory. The gamma controller health
detection assembly can be configured to run algorithms that detect
if one or more gamma sensors appear to be malfunctioning or have
previously malfunctioned.
Inventors: |
MILLER; KENNETH; (HOUSTON,
TX) ; ERDOS; ABRAHAM; (HOUSTON, TX) ; ERDOS;
DAVID; (HOUSTON, TX) ; MATHIESON; JAMES;
(CONROE, TX) ; CARTER; JOSHUA; (CONROE,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
REME TECHNOLOGIES, LLC |
CONROE |
TX |
US |
|
|
Assignee: |
REME TECHNOLOGIES, LLC
CONROE
TX
|
Family ID: |
51702287 |
Appl. No.: |
14/454935 |
Filed: |
August 8, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14304685 |
Jun 13, 2014 |
8866069 |
|
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14454935 |
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Current U.S.
Class: |
250/261 |
Current CPC
Class: |
G01T 7/005 20130101;
G01V 5/06 20130101; G01V 8/20 20130101; G01V 5/04 20130101; G01T
1/17 20130101 |
International
Class: |
G01T 1/17 20060101
G01T001/17; G01V 5/06 20060101 G01V005/06 |
Claims
1. A downhole measurement assembly to facilitate the reliable
downhole measurement of radiation given off by geological
formations adjacent a wellbore, the downhole measurement assembly
comprising: one or more gamma probes to sense radiation given off
by downhole formations and to provide output pulses representative
of the radiation, one or more microcontrollers, at least one of
which is configured to receive the output pulses from the one or
more of gamma probes, at least one microcontroller configured to
detect when one of the one or more of gamma probes is providing
output pulses that may indicate one or more probes has
malfunctioned, the microcontroller configured to assign a
representative data value to the output pulses of the one or more
gamma probes, to calculate a differential diversion factor for each
of the one or more gamma probes, and to determine when the one or
more of the gamma probes differential diversion factor indicates
the one or more gamma probes may be close to malfunctioning, and
one or more memory elements to store gamma controller assembly
executable code and gamma probe data.
2. The downhole measurement assembly of claim 1, further
comprising: one or more power supplies to provide power to the one
or more microcontrollers, the one or more gamma probes, and the one
or more memory elements.
3. The downhole measurement assembly of claim 1, further
comprising: one or more communications pathways between each of the
one or more gamma probes and at least one of the one or more
microcontrollers, wherein the output pulses of each of the one or
more gamma probes are configured to be communicated on the one or
more communications pathways to the at least one of the one or more
microcontrollers for interpretation and logging to memory.
4. The downhole measurement assembly of claim 1, wherein the one or
more microcontrollers are configured to analyze the output pulses
of each of the one or more gamma probes to determine if one or more
probes has malfunctioned.
5. The downhole measurement assembly of claim 1, wherein the one or
more microcontrollers are configured to disqualify or disregard the
output pulses from each of the one or more gamma probes, when the
each of the one or more gamma probes is determined to be close to
malfunctioning or determined to be malfunctioning.
6. The downhole measurement assembly of claim 5, wherein the one or
more microcontrollers are configured to continue analyzing the
output pulses from each of the one or more gamma probes that have
been disqualified or disregarded and re-qualify each of the one or
more gamma probes that have returned to acceptable operating
parameters.
7. The downhole measurement assembly of claim 1, further
comprising: one or more communication pathways to convey gamma
probe data between the downhole measurement assembly and a remote
computer.
8. A method of measuring radiation given off by geological
formations downhole, the method including the following steps:
deploying a radiation measurement assembly downhole, the radiation
measurement assembly comprising: one or more gamma probes to sense
radiation given off by downhole formations and provide output
pulses representative of the radiation, one or more
microcontrollers, at least one of which is configured to calculate
differential diversion factors for the output pulses of the one or
more gamma probes, and one or more memory elements for storing the
gamma controller assembly executable program and for logging gamma
probe data; sensing radiation given off downhole from formations by
the one or more of gamma probes, the one or more of gamma probes
each generating pulses that are communicated to at least one of the
one or more microcontrollers; interpreting the pulses given off by
each of the one or more of gamma probes by at least one of the one
or more microcontrollers such that the pulses are each assigned
representative data; calculating, by at least one of the one or
more microcontrollers, a differential diversion factor for each of
the one or more gamma probes; determining if one or more of the
differential diversion factors calculated for each of the one or
more gamma probes may indicate that a particular one of the gamma
probes may be close to malfunctioning; and disqualifying one of the
one or more of gamma probes, responsive to the determining step,
such that the pulses output by the disqualified gamma probe are no
longer considered valid.
9. The method of claim 8, further comprising the step of:
determining of one or more of the differential diversion factors
calculated for each of the one or more gamma probes indicates that
a particular one of the gamma probes has malfunctioned.
10. The method of claim 9, further comprising the step of:
disqualifying or flagging previously gathered data associated with
the one or more gamma probes that has been determined to have
malfunctioned, at least for a time period over which the gamma
probe was known to have been malfunctioning.
11. A downhole measurement assembly to facilitate the reliable
downhole measurement of radiation given off by geological
formations adjacent a wellbore, the downhole measurement assembly
comprising: one or more of gamma probes to sense radiation given
off by downhole formations and provide output pulses representative
of the radiation, one or more microcontrollers, at least one of
which is configured to detect when one of the one or more of gamma
probes is providing output pulses that may indicate the probe has
malfunctioned, a communication pathway between each of the one or
more of gamma probes and at least one of the one or more
microcontrollers wherein the output pulses of each of the one or
more of gamma probes are communicated on the communication pathway
to at least one of the one or more microcontrollers for
interpretation and logging, one or more communication pathways to
convey gamma probe data between the downhole measurement assembly
and a remote computer, and non-transitory computer-readable storage
medium in communication with the one or more microcontrollers with
an executable program stored thereon, the executable program
comprising a set of instructions that, when executed by the one or
more microcontrollers, causes the one or more microcontrollers to
perform the operations of: sensing radiation given off downhole
from formations by the one or more of gamma probes, the one or more
of gamma probes each generating pulses that are communicated to at
least one of the one or more microcontrollers; interpreting the
pulses given off by each of the one or more of gamma probes by at
least one of the one or more microcontrollers such that the pulses
are each assigned representative data; calculating, by at least one
of the one or more microcontrollers, a differential diversion
factor for each of the one or more gamma probes; determining if one
or more of the differential diversion factors calculated for each
of the one or more gamma probes may indicate that a particular one
of the gamma probes may be close to malfunctioning; and
disqualifying one of the one or more of gamma probes, responsive to
the determining step, such that the pulses output by the
disqualified gamma probe are no longer considered valid.
12. A downhole measurement assembly as defined in claim 11, wherein
the non-transitory computer-readable storage medium further
comprises a set of instructions that when executed by the one or
more microcontrollers, causes the one or more microcontrollers to
perform the operations of: interpreting the pulses given off by at
least one of the disqualified gamma probes by at least one of the
one or more microcontrollers such that the pulses are each assigned
representative data; calculating, by at least one of the one or
more microcontrollers, a differential diversion factor for each of
the at least one disqualified gamma probes; determining if one or
more of the differential diversion factors calculated for each of
the at least one disqualified gamma probes may indicate that a
particular one of the disqualified gamma probes has resumed
functioning within predetermined bounds; and re-qualifying one of
the disqualified gamma probes, responsive to the determining step,
such that the pulses output by the re-qualified gamma probe are
considered valid.
13. A downhole measurement assembly as defined in claim 11, wherein
the non-transitory computer-readable storage medium further
comprises a set of instructions that when executed by the one or
more microcontrollers, causes the one or more microcontrollers to
perform the operations of: logging representative data to memory by
at least one of the one or more microcontrollers.
14. A computer-implemented method to facilitate the reliable
downhole measurement of radiation given off by geological
formations adjacent a wellbore, the computer-implemented method
comprising the following steps: sensing radiation given off
downhole from formations by the one or more of gamma probes, the
one or more of gamma probes each generating pulses that are
communicated to at least one of the one or more microcontrollers;
interpreting the pulses given off by each of the one or more of
gamma probes by at least one of the one or more microcontrollers
such that the pulses are each assigned representative data;
calculating, by at least one of the one or more microcontrollers, a
differential diversion factor for each of the one or more gamma
probes; determining if one or more of the differential diversion
factors calculated for each of the one or more gamma probes may
indicate that a particular one of the gamma probes may be close to
malfunctioning; and disqualifying one of the one or more of gamma
probes, responsive to the determining step, such that the pulses
output by the disqualified gamma probe are no longer considered
valid.
15. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
interpreting the pulses given off by at least one of the
disqualified gamma probes by at least one of the one or more
microcontrollers such that the pulses are each assigned
representative data; calculating, by at least one of the one or
more microcontrollers, a differential diversion factor for each of
the at least one disqualified gamma probes; determining if one or
more of the differential diversion factors calculated for each of
the at least one disqualified gamma probes may indicate that a
particular one of the disqualified gamma probes has resumed
functioning within predetermined bounds; and re-qualifying one of
the disqualified gamma probes, responsive to the determining step,
such that the pulses output by the re-qualified gamma probe are
considered valid.
16. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
logging representative data to memory by at least one of the one or
more microcontrollers.
17. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
indicating to a remote computer at the surface when one or more of
the gamma probes has been disqualified.
18. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
indicating to a remote computer at the surface when one or more of
the gamma probes has been re-qualified.
19. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
communicating to a measurement while drilling tool, by the one or
more microcontrollers, representative data of the measurements
taken by the one or more gamma probes.
20. The computer-implemented method of claim 14, wherein the
computer-implemented method further comprises the following steps:
communicating to a measurement while drilling tool, the calculated
differential diversion factors associated with the one or more
gamma probes.
21. A system to facilitate the reliable measurement and analysis of
radiation given off by geological formations adjacent a wellbore,
the system comprising: a downhole measurement assembly, comprising:
one or more gamma probes to sense radiation given off by downhole
formations and to provide output pulses representative of the
radiation, one or more memory elements to store gamma controller
assembly executable code and gamma probe data, and one or more
microcontrollers, at least one of which is configured to receive
the output pulses from the one or more of gamma probes, the at
least one microcontroller configured to assign a representative
data value to the output pulses of the one or more gamma probes and
write the representative data value to the one or more memory
elements, thereby logging the representative data, the logged
representative data forming the gamma probe data; a surface
assembly, comprising: one or more computers configured to process
the gamma probe data either in real-time or by post-processing the
data to detect when the gamma probe data may indicate that one or
more probes has malfunctioned, the one or more computers configured
to calculate a differential diversion factor for each of the one or
more gamma probes over a pre-determined period of time, the one or
more computers further configured to determine when the one or more
of the gamma probes differential diversion factor indicates the one
or more gamma probes may be close to malfunctioning or
malfunctioning.
22. The downhole measurement assembly of claim 21, further
comprising: one or more power supplies to provide power to the one
or more microcontrollers, the one or more gamma probes, and the one
or more memory elements.
23. The downhole measurement assembly of claim 21, further
comprising: one or more communications pathways between each of the
one or more gamma probes and at least one of the one or more
microcontrollers, wherein the output pulses of each of the one or
more gamma probes are configured to be communicated on the one or
more communications pathways to the at least one of the one or more
microcontrollers for interpretation and logging to memory.
24. The surface assembly of claim 21, wherein the one or more
computers are configured to analyze the gamma probe data in
realtime to determine if one or more gamma probes has
malfunctioned.
25. The surface assembly of claim 21, wherein the one or more
computers are configured to disqualify or disregard the gamma probe
data from each of the one or more gamma probes, when the each of
the one or more gamma probes is determined to be close to
malfunctioning or determined to be malfunctioning.
26. The surface assembly of claim 25, wherein the one or more
microcontrollers are configured to continue analyzing the gamma
probe data from each of the one or more gamma probes that have been
disqualified or disregarded and re-qualify each of the one or more
gamma probes that have returned to acceptable operating
parameters.
27. The system of claim 21, further comprising: one or more
communication pathways to convey gamma probe data in real-time
between the downhole measurement assembly and the surface
assembly.
28. The system of claim 21, further comprising: one or more systems
to convey gamma probe data between the downhole measurement
assembly and the surface assembly for post-processing of the gamma
probe data at the surface.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
Non-Provisional patent application Ser. No. 14/174,700 filed on
Feb. 6, 2014, which is herein incorporated by reference in its
entirety. This application further claims the benefit of U.S.
Provisional Patent Application Ser. No. 61/835,188 filed on Jun.
14, 2013, U.S. Provisional Patent Application Ser. No. 61/886,509
filed on Oct. 3, 2013, and U.S. Provisional Patent Application Ser.
No. 61/976,347 filed on Apr. 7, 2014, each of which is herein
incorporated by reference in its entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to downhole radiation
measurement assemblies.
[0004] 2. Description of the Related Art
[0005] Downhole radiation measurement assemblies have been used in
drilling operations for some time. In downhole drilling it is
useful identify sub-surface rock formations and customize drilling
assemblies and drilling methods to suit a particular geological
formation. This can be useful when, for example, a drilling rig has
been configured to be effective for a particular type of rock
formation and characteristics of the rock formation change as the
wellbore extends deeper beneath the surface. It would thus be
useful to identify rock formations present at various drilling
depths at a wellsite. Downhole radiation measurement assemblies
measure the naturally occurring low level radiation that is given
off by rock formations downhole. Different types of rock can give
off differing amounts of radiation or radiation having other
differing characteristics and if measured accurately, the type of
rock formations at different depths can be identified. Often,
radiation measurement assemblies are deployed downhole and many
measurements are taken at different depths in a well. The sensor
measurements can then be communicated uphole and processed to
determine the particular types of rock formations present at
various depths at a particular wellsite. Radiation measurement
assemblies can experience harsh vibrations and temperatures as well
as other environmental conditions during the installation process,
when taking radiation measurements, while sitting downhole, and
also during retrieval. Over time drilling operations have seen
drilling to greater depths, causing radiation measurement
assemblies to experience increasingly harsher environments. In
addition, many of the radiation measurement sensors can be
particularly sensitive and malfunction in response to vibration,
harsh temperatures, and other environmental factors. Vibration
factors can be particularly problematic for radiation measurement
sensors used in downhole radiation measurement assemblies. This can
be due in part to the construction and sensitive components of
radiation measurement assemblies. These factors and others continue
to create the need for more advanced and reliable downhole
radiation measurement assemblies.
[0006] Radiation measurement assemblies are commonly deployed with
measurement while drilling tools. The purpose of measurement while
drilling tools is to collect various sensor based measurements and
facilitate the communication of the measurements to the surface.
Measurement while drilling tools can be deployed with sensors for
measuring various downhole conditions such as temperature, flow
data, drillstring rotation, location information, radiation
readings, or other useful downhole conditions. The sensors deployed
alongside or as a part of measurement while drilling tools will
often be configured to communicate data with the microcontroller or
microprocessor that is a part of the measurement while drilling
tool assembly deployed downhole. This communication may be made
using standard protocols that transmit over bus connections between
the measurement while drilling tool and the various sensors.
Measurement while drilling tools can then communicate data from the
sensors uphole to remote computers or data logging equipment.
Measurement while drilling tools can be deployed by wireline or
inline with the drillstring and can include remote power supplies
or receive power over cabling run downhole. It is common to deploy
a radiation probe that is connected to a measurement while drilling
tool downhole to perform radiation measurements at various depths.
The measurement while drilling tool can be configured to receive
gamma probe data, which for example may be in the form of a pulse
train, and then process and communicate the data to remote
computers on the surface.
[0007] It would be desirable to have radiation measurement
assemblies that include greater resilience to vibration, harsh
temperatures, and other environmental factors that are present
downhole. Further, it would be desirable to provide increased
meantime between failures of radiation measurement assemblies
installed downhole. This would allow greater drilling time,
increased measurement time, and decreased time spent installing,
retrieving, and servicing radiation measurement assemblies. It
would further be desirable to decrease the time committed to
servicing radiation measurement assemblies due to the failures of
radiation measurement sensors that are particularly sensitive to
the harsh environments downhole.
SUMMARY OF THE INVENTION
[0008] The present invention provides an improved gamma probe
health detection assembly including advanced gamma fail detection
prediction algorithms and methods. Radiation measurements are taken
by one or more gamma sensors that are part of the improved gamma
probe health detection assembly. When the one or more gamma sensors
detect radiation they transmit pulses to a microcontroller that
interprets and checks the measurements. The measurements can be
logged, communicated uphole, or both. In an embodiment the
microcontroller writes the measurements to memory downhole and the
memory contents are later retrieved from the tool at the surface or
offsite. Once sent or retrieved uphole, the measurements can then
be further processed and communicated to determine and display the
make-up of geological formations downhole. The gamma controller
assembly includes one or more gamma sensors, one or more
microcontrollers, memory for storing the program run by the gamma
controller assembly and input/output ports among other components.
Additional memory for logging gamma sensor readings can also
optionally be configured. Gamma sensor data from an embodiment
including multiple gamma sensors can be selected or averaged by the
microcontroller and stored to memory or stored as independently
logged values to memory. The sensor data can then be sent uphole to
another microcontroller or computer based system that can then
further process, communicate, and display the data. The gamma
controller assembly can be configured to run gamma probe health
detection algorithms that detect if one or more gamma sensors
appear to be malfunctioning, and if an apparent malfunction has
occurred, the assembly can be configured to communicate only the
data from the correctly functioning sensors uphole. In another
embodiment the gamma controller assembly can send all sensor data
uphole and communicate what data is trusted and what data is not
trusted. Once uphole, the gamma sensor data can then be further
communicated to another microcontroller or computer based system
for additional evaluation, processing, storage, or display.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Various aspects and attendant advantages of one or more
exemplary embodiments and modifications thereto will become more
readily appreciated as the same becomes better understood by
reference to the following detailed description, when taken in
conjunction with the accompanying drawings, wherein:
[0010] FIG. 1 depicts a block diagram of an embodiment of the gamma
probe health detection assembly, also referred to as a multiple
gamma controller assembly.
[0011] FIG. 2 depicts a schematic representation of the multiple
gamma controller assembly of FIG. 1.
[0012] FIG. 3 depicts a schematic representation of the multiple
gamma controller assembly of FIG. 1.
[0013] FIG. 4 depicts a side view of the multiple gamma controller
assembly of FIG. 1.
[0014] FIG. 5 depicts a side perspective view of the multiple gamma
controller assembly of FIG. 1.
[0015] FIG. 6 depicts a side view of the multiple gamma controller
assembly of FIG. 1.
[0016] FIG. 7 depicts a side perspective view of the multiple gamma
controller assembly of FIG. 1 within a well bore.
[0017] FIG. 8 depicts a side perspective view of an embodiment of
the chassis of the multiple gamma controller assembly of FIG.
1.
[0018] FIG. 9 depicts a side perspective view of an embodiment of
the circuit board of the multiple gamma controller assembly of FIG.
1.
[0019] FIG. 10 depicts a side perspective view of an embodiment of
a cross-over member of the multiple gamma controller assembly of
FIG. 1.
[0020] FIG. 11 depicts a block diagram of a measurement while
drilling tool having only a single gamma sensor.
[0021] FIG. 12 depicts a block diagram of a measurement while
drilling tool having the multiple gamma controller assembly of FIG.
1.
[0022] FIG. 13A depicts a first portion of a flow chart of a
kick-out algorithm for the multiple gamma controller assembly of
FIG. 1, with FIG. 13B depicting a second portion.
[0023] FIG. 13B depicts the second portion of a flow chart of a
kick-out algorithm for the multiple gamma controller assembly of
FIG. 1, with FIG. 13A depicting the first portion.
[0024] FIG. 14A depicts an illustration of raw gamma probe output
values from two gamma probes.
[0025] FIG. 14B depicts an illustration of processed gamma probe
output values from two gamma probes, showing a calculated
differential diversion factor for the probe outputs.
[0026] FIG. 15 depicts a flow chart for a gamma requalification
process.
[0027] FIG. 16 depicts a flow chart for a gamma health monitoring
process.
[0028] FIG. 17 depicts a flow chart for a gamma output process
where a gamma health process and a gamma requalification process
are included in the gamma output process.
DETAILED DESCRIPTION
[0029] One purpose of the improved gamma controller assembly can be
to increase the reliability of downhole gamma sensor measurements.
One of the frequent failures in a measurement while drilling system
is for the gamma probe to fail. This can be very costly to remedy
as the entire drill string has to be pulled from the well to
replace the gamma probe, if there is even a spare available.
[0030] To mitigate this failure mode, the gamma probe health
detection controller assembly facilitates redundant gamma probes in
a single measurement while drilling tool, a configuration which can
also be referred to as a multiple gamma controller assembly. The
gamma probe health detection assembly can also utilize just a
single gamma probe and run advanced failure detection algorithms to
determine when the single probe has failed or may be nearing
failure. Additionally, readings from single or multiple gamma
probes can be post analyzed at the surface or offsite using
advanced algorithms to determine if the runs can be trusted over
certain time periods. The multiple gamma controller assembly can
also be configured to log various parameters of the tool downhole
to assist with failure analysis when the tool is serviced. Using
heuristics, if the multiple gamma controller assembly determines
that each gamma probe is operating correctly, the multiple gamma
controller assembly can then output a single pulse train which can
be a combined and filtered or alternately a single averaged reading
from the multiple individual gamma probes to the measurement while
drilling tool. In an alternate embodiment, the combined, filtered,
or averaged reading output by the multiple gamma controller
assembly can be communicated over a CAN bus or other bus known in
the industry, to either the measurement while drilling tool or to
other equipment uphole via mud pulsers, signal lines, or other
communication methods. If however the multiple gamma controller
assemblies' heuristics determine that one of the gamma probes has
failed, it can exclude the failed gamma probe from the filtered
output and only output a filtered pulse train based on the readings
from the remaining gamma probes. In the preferred embodiment, it is
preferred that two gamma sensor probes would be configured in each
multiple gamma controller assembly; however, it is equally possible
that three or more probes could be configured in a single assembly.
For this embodiment the multiple gamma controller assembly may also
be referred to as a dual gamma controller assembly. The mode in
which a single pulse train is output to the measurement while
drilling tool in particular can be designed to work with
measurement while drilling systems that expect to see one pulse
train from a single gamma sensor downhole. In an alternate
embodiment, data from each gamma sensor can be communicated to a
measurement while drilling tool or uphole with an indicator as to
what sensor data may be trusted and what sensor data may be
incorrect due to a possibly malfunctioning gamma probe.
[0031] Referring to FIGS. 1, 2, and 3, the gamma probe health
detection assembly, which can also be referred to as a multiple
gamma controller assembly 10 has a controller module 18 that can be
configured to include one or more microcontrollers or processors
20; one or more power supplies 30; memory 40 for storing the main
executable program, for logging, and for storing configuration
parameters; and accelerometers 50 or similar sensors for sensing
shock and vibration. The multiple gamma controller assembly 10
further includes multiple gamma probes 60a and 60b, though more
than two probes can be configured in an alternate embodiment.
Additionally, in an alternate embodiment of the gamma probe health
detection assembly, just one gamma probe may be configured, in this
embodiment the assembly can be configured with advanced gamma probe
health detection algorithms. Optionally, advanced gamma probe
health detection algorithms can also be utilized in an embodiment
having multiple probes configured. The controller module 18 can be
configured to provide power to the gamma probes 60a and 60b over
gamma probe power lines 62a and 62b. Data lines 64a and 64b also
extend between the controller module 18 and the gamma probes 60a
and 60b. In addition, the multiple gamma controller assembly 10 can
be configured to include power lines 70, serial communication lines
72, and gamma sensor pulse output lines 74 that extend to a
measurement while drilling tool (not shown) or from lines running
from the surface to the tool. A single memory element can be shared
for the main executable program, logging, and storing configuration
parameters, or multiple memory elements can be utilized. There are
three primary functions of the microcontroller or processor 20: (1)
monitoring the health of the gamma probes, (2) logging tool
parameters for failure analysis, and (3) sending gamma probe
measurement data to a measurement while drilling tool or directly
uphole. The multiple gamma controller assembly 10 can have multiple
modes of operation, which are not mutually exclusive. In an
embodiment the multiple gamma controller assembly 10 can have a
transparent mode, where the controller will simply output a
combined, filtered, or averaged pulse train to a measurement while
drilling tool (not shown), and thus appearing to the measurement
while drilling tool as a single gamma probe. This approach provides
additional accuracy and reliability to current systems that are
only configured to interact with a single gamma probe. In this
mode, the measurement while drilling systems are "tricked" into
thinking they are only receiving output from a single probe. In
fact, this approach provides increased accuracy and reliability for
low bandwidth systems that could not provide enough bandwidth to
transmit data from multiple gamma sensors uphole. An alternate mode
of operation allows the multiple gamma controller assembly to
transmit data from the gamma probes and overall tool health status
to the measurement while drilling unit as generic data values over
the serial bus inside the tool, or over other bus types. For many
types of measurement while drilling tools, this bus can have
limited bandwidth, but for higher bandwidth systems, more sensor
data could be communicated using this mode. Finally, if higher
bandwidth systems are used, another alternate embodiment can allow
for sensor data from each gamma probe sensor to be sent to the
measurement while drilling tool or even uphole as separate pulse
trains or by other means that would allow all of the sensor data or
data from a select multiple number of sensors to be sent
uphole.
[0032] Referring to FIG. 4, a multiple gamma stack assembly 100 is
shown. The multiple gamma stack assembly 100 includes a multiple
gamma controller chassis 110 that includes a controller circuit
board module 120; a first gamma module 130; a second gamma module
140; a bus-cross-over module 150, and a snubbing end 160. Referring
to FIG. 5, the multiple gamma controller chassis 110 houses the
controller circuit board module 120 that is analogous to controller
module 18 referenced in FIGS. 1-3. Module 120 can be configured to
include one or more microcontrollers or processors; one or more
power supplies or power supply voltage regulators; memory for
storing the main executable program, for logging, and for storing
configuration parameters; and accelerometers or similar sensors for
sensing shock and vibration. In an embodiment, each of these
sub-components may alternately be configured on separate circuit
boards or as a part of other modules within the system. The chassis
110 provides sturdy connection ports 112 for connecting electrical
lines between modules. A top hatch 114 and bottom hatch 116 protect
the controller circuit board module 120 from the harsh downhole
environments and also allow easy access for servicing. In alternate
embodiments, different protective enclosures can be configured to
protect the controller circuit board module 120 and the various
other components of the multiple gamma stack assembly 100.
[0033] Referring to FIG. 6, a multiple gamma stack assembly 100 is
shown connected to a battery unit 200 and a pulser driver 300. The
pulser driver 300 is one example of a communication system that can
be configured to send information uphole or to the surface and
receive information downhole from the surface. The pulser driver
300 can be configured to send and receive pulses through the
drilling mud that can be detected by sensors. The pulses can then
be interpreted by the sensors or other connected equipment. When
deployed downhole this configuration or similar configurations may
be used, for example non-pulser based communications systems such
as wire based systems may also be used to send information and
communicate with surface equipment. Referring to FIG. 7, an
alternate perspective view of an example of the multiple gamma
stack assembly 100 is shown. Referring to FIG. 8, an example of the
gamma controller chassis 110 is shown with the top hatch 114
connected to the bottom hatch 116, both of which serve to protect
the controller circuit board module 120 from harm. FIG. 9 shows an
example of the side perspective view of the controller circuit
board module 120 that, as described above, can be configured to
include various components of the multiple gamma controller
assembly.
[0034] Referring to FIG. 10, an example of the bus cross-over
module 150 is shown. For multiple gamma controller assemblies that
include three or more gamma probes, multiple bus cross-over modules
150 can be configured to allow the connection of additional probes.
In an embodiment, the bus cross-over module 150 facilitates the
connection of multiple gamma probes to a multiple gamma controller
in a system that was originally designed for the use with only a
single gamma probe. The cross-over module 150 can be configured to
place gamma probe output line data onto spare signal carrying lines
of the bus, the multiple gamma controller can then read and
interpret the output of the gamma probes in these lines. FIG. 11 is
an example block diagram showing the components and wiring layout
of a measurement while drilling tool 400 having a single gamma
probe 410. In this example a pulser driver 420 serves as the
surface communication link to the tool 400 and battery power is
provided to the various components through battery one 430 and
battery two 440. A main processing unit ("MPU") 450, triple power
supply ("TPS") 460, and orientation module ("OM") 470 are also
included in this configuration. The gamma probe 410 output
radiation measurement readings on the gamma bus line 480. The
readings are then processed by the MPU 450 which then sends
representative data values or the full pulse train information to
the surface through the pulser drive 420. In addition to the gamma
bus line 480, the bus 405 that runs between the various components
can include a ground line ("GND") 490, a battery one line ("Batt1")
491, a battery two line ("Batt2") 492, a BBus signal line ("BBus")
493, a qBus signal line ("gBus") 494, a pulse signal line ("Pulse")
495, a flow signal line ("Flow") 496, an m1 signal line ("M1") 497,
and an m2 signal line ("M2") 498. The bus described carries power
from the batteries to the various components and also serves as the
communication links between the components.
[0035] Referring to FIG. 12, an example block diagram showing the
components and wiring layout of a measurement while drilling tool
500 having multiple gamma probes and a multiple gamma controller
514 is shown. Gamma probe 510 and gamma probe 512 output their
radiation measurement readings to the multiple gamma controller
514. The bus cross-over module as described in FIG. 10 can be
configured when implementing this layout to, re-route the output of
each gamma probe onto spare signal lines that are part of the bus.
In an embodiment, the gamma probe data can be routed to the
microcontroller of the multiple gamma controller assembly and the
microcontroller runs algorithms against the gamma probe output data
to determine the gamma probe data to place onto the gamma probe
output line or lines that can then be communicated to a measurement
while drilling tool or other data channels that communicate the
information uphole. Similar to the single probe configuration
described in FIG. 11, in this example a pulser driver 520 serves as
the surface communication link for the tool 500 and battery power
can be provided to the various components through a battery one 530
and a battery two 540. A main processing unit ("MPU") 550, triple
power supply. ("TPS") 560, and orientation module ("OM") 570 can
also be included in this configuration. The first gamma probe 510
outputs radiation measurement readings on the gamma output line 580
and the second gamma probe 512 outputs radiation measurement
readings on the gamma output line 584. The readings are then
received and processed by the multiple gamma controller 514, which
combines, averages, or filters the readings using one or more of
the methods described herein. The multiple gamma controller 513
then continuously generates a representative gamma output value
that can be sent to the MPU 550 or the pulser driver 520 for
communication uphole. Similarly to the methods described above,
heuristics can be employed by the multiple gamma controller 514 and
probe data can be adjusted, disqualified, and re-qualified
accordingly. In addition to the gamma bus line 580, the bus that
runs between the various components can include a ground line
("GND") 590, a battery one line ("Batt1") 591, a battery two line
("Batt2") 592, a BBus signal line ("BBus") 593, a qBus signal line
("qBus") 594, a pulse signal line ("Pulse") 595, a flow signal line
("Flow") 596, an m1 signal line ("M1") 597, and an m2 signal line
("M2") 598. The bus described carries power from the batteries to
the various components and also serves as the communication links
between the components. The bus described in this paragraph is
merely one embodiment and configuration of the multiple gamma
controller assembly. Other bus configurations, tool configurations,
communication protocols, and communication topologies can be used
in conjunction with the multiple gamma controller assembly. Using
the methods described, a multiple gamma controller assembly can be
integrated into a tool that typically only uses one gamma probe,
such as the system described in reference to FIG. 11. Bus
cross-over modules can be configured for use in the described
system to carry the gamma probe output data over spare bus signal
lines or alternatively other signal lines apart from the main bus
can be used. The multiple gamma controller assembly can also be
integrated into other types of systems that are configured to only
use one gamma probe by default.
[0036] In an embodiment, the multiple gamma controller assembly can
be configured to interact with multiple measurement while drilling
tools, different types of measurement while drilling tools, or
other tools that allow communication to the surface. For each of
these tools, different amounts of bandwidth may be available to
transmit data uphole and the multiple gamma controller assembly can
be configured to send more or less gamma sensor data depending on
the bandwidth available. For example, the frequency of the readings
sent to the surface can be adjusted according to the bandwidth
available for the transmission.
[0037] Further, in an embodiment, the filtering of the output
counts from the multiple gamma probes could simply be the average
of the counts per second (or other time interval) from the multiple
gamma probes. Additionally, the filtering could also be a weighted
average of the gamma sensor outputs, if certain sensors are
determined to be in better health than the others. More advanced
filtering may also be performed using a state estimator to estimate
the overall background radiation based on the readings from the
multiple gamma probes. The filtered output can also take into
account the API calibration factors for each gamma probe, and these
values can be stored in the multiple gamma controller assembly's
memory.
[0038] The microcontroller or processor of the multiple gamma
controller assembly can continually monitors the pulse train output
of each gamma probe which should correspond directly to the gamma
radiation levels downhole. The microcontroller can be configured to
keep statistics about the performance of each gamma probe, and if,
based on its heuristics it determines that one of the gamma probes
has failed, it will exclude from the combined, filtered, or
averaged, output the counts of the failed probe.
[0039] Several different heuristics can be used to determine if a
gamma probe is or may be malfunctioning. In an embodiment, those
heuristics may optionally include, but are not limited to: (1) high
counts, that is counts greater than some threshold, (2) low counts,
that is counts less than some threshold, (3) counts changing too
quickly, meaning that the rate at which the counts are increasing
or decreasing (the derivative of the counts per second with respect
to time) is too high/low, (4) the standard deviation over time is
increasing beyond an acceptable limit, (5) kurtosis analysis, (6)
skew of counts over time, or (7) other statistical measurements. If
a gamma probe is determined to be malfunctioning based on the
heuristics, then, for a microcontroller operating in a single pulse
train mode, the counts from the probe may no longer be included in
the filtered output or pulse train of the microcontroller.
Likewise, in a mode where multiple sensor outputs are being
communicated to the measurement while drilling tool or uphole, when
the heuristics detect the possible malfunction of a sensor, the
output data for that sensor may be tagged as invalid or potentially
incorrect. However, the outputs from the failed gamma probe will be
continually monitored to determine whether or not the gamma probe
has recovered. Occasionally gamma probes output unreasonably high
counts as the temperature increases, or if a shock event occurs,
but then recover once the temperature decreases or the
shock/vibration levels decrease. If a failed gamma probe is
determined to be within the operational limits once again for some
set period of time, then it can once again be included in the
filtered output or pulse train or the tagging included with the
gamma probe data can be changed back to valid or good.
[0040] In an embodiment, the microcontroller can be configured to
constantly compare the values read from both gamma probes and
compare or check the health status data for each of the gamma
probes as well. Generally, there are two main failure modes for the
gamma probes, high counts and low counts. Either failure mode has
to do with some portion of the standard gamma sensor failing. For
example, the crystals can crack, the photomultiplier tubes can
crack or otherwise fail, the high voltage power supply can drift or
stop supplying power, and in some cases the discriminator circuit
may fail as well. Typically these failures cause a gamma sensor to
return no counts at all or abnormally high counts. Based on this
notion the microcontroller of the multiple gamma controller
assembly can be configured to run algorithms that check for high
and low counts. In an embodiment, a low and a high threshold are
set in accordance with readings anticipated from gamma sensors
downhole. These threshold values may be adjusted for different
types or brands of sensors, or to accommodate for desired
thresholds at a particular wellsite. If the readings from any one
gamma sensor exceed these bounds, high or low, it can be
immediately disqualified from the system and any averaging
calculation that may be performed in a given embodiment. In some of
the alternate embodiments where gamma sensor readings from more
than one gamma probe are conveyed, the data from an out of bounds
probe can be merely flagged as invalid or disqualified. To be
considered operational again, the reading must return to the
acceptable range and stay within bounds for a set timeframe. If the
sensor stays out of bounds for a large amount of time, it can be
permanently disqualified from the calculation, at least for a given
installation or over a certain time period.
[0041] In an alternate embodiment where three or more gamma probes
are configured, a majority rules protocol can be put into place. In
this setup the two probes with the closest counts are used and can
be combined, averaged, or filtered, with the readings from the
third probe being discounted for a given reading comparison or for
a given time period. In this configuration, should one or more
probes fail, the remaining probes can be switched from the majority
rules protocol back to other methods where all of the probes values
are again combined, averaged, filtered, or otherwise processed and
then communicated to the measurement while drilling tool or
uphole.
[0042] Some probes can also be sensitive to temperature and have
counts that drift at temperature extremes. Comparing temperature
readings to count data can be used to determine if a particular
probe might be experiencing temperature drift and adjustment can be
made to the count values from that probe. Alternatively, if a
temperature drift passes a pre-determined threshold the probe can
be disqualified temporarily and re-qualified later if readings
return to within the pre-determined threshold.
[0043] Referring to FIGS. 13A and 13B, two portions of a single
flowchart of an example algorithm 600 run by the multiple gamma
controller is shown. In this example, the system starts 610 and one
algorithm routinely checks and logs telemeter status 660 so that
location information can be associated with the readings collected
by the probes. The health of the telemeter status readings can
optionally be checked as part of this sequence using heuristics
based algorithms. Collected data may be disqualified or data
logging may be suspended if telemeter readings are called into
question. A routine algorithm can also be run to evaluate gamma one
620 and evaluate gamma two 640, and determine if the counts
received are between pre-determined high and low values. The
pre-determined values can be different for different probe types of
for different individual probes of the same type, this may be based
on testing, calibration values, or the previous use of a given
probe. Additionally, the high and low values may be set to
different ranges for different rock formations and other
environmental conditions. The gamma probe readings are each
evaluated to determine if they are in bounds 621, 641 of the
pre-determined range. If a value is determined to be in bounds 621,
641, a routine algorithm then checks to see if the gamma probe was
recently flagged 630, 650. If the probe was flagged 630 650, it is
not considered in the average 631, 651 but instead checked to be in
bounds for a pre-determined time 632, 652, in this example, one
minute. If the probe is in bounds for greater than one minute 632,
652, the flag disqualifying the probe is cleared 633, 653, and the
next time the probe is checked and verified in bounds the readings
from that probe will be considered in the average 631, 651.
Alternatively, the probe readings may be considered in an average,
combined, filtered, considered in a majority rules protocol
comparison, or otherwise used as described in the various
algorithms. As this is an example, in an alternate embodiment the
probes can also be flagged and temporarily or permanently for
various other reasons, consistent with what has been mentioned
previously. When a probe is determined to be in bounds 621, 641 and
determined to be not flagged 630, 650, it may then be considered in
average 631, 651 or otherwise considered-good by the multiple gamma
controller. A gamma probe that provides out of bounds data is
flagged 622, 642 the first time it provides an out of bound result.
If the gamma probe continues to provide out of bounds results in
excess of the configured ten minute timeframe 623, 643 of this
example, the probe can be permanently disqualified from use 624,
644. In this event, the multiple gamma controller assembly can be
configured to send a message to a remote computer indicating the
probes failure (not shown). When a probe is permanently
disqualified 624, 644, evaluation of the probes output is stopped
625, 690. In an embodiment, the described sequences can optionally
be carried out on more than two probes. Also, in an embodiment,
this sequence need not be carried out on all of the probes
configured, some probes can optionally remain inactive in a
particular system configuration. If all of the probes in a given
system are no longer being evaluated a count of zero will be
recorded 634, indicating there may be a problem with the probes. As
long as one probe remains operational and is returning readings,
the tool can remain in use until a convenient service window opens,
at which time the failing probes can be replaced.
[0044] More complex algorithms can be applied. For example, gamma
sensors can be disqualified if one drifts apart from the other, or
as well if they become too noisy and return values that are within
bounds but erratic. All of the thresholds and disqualification
parameters are configurable. In another embodiment, the multiple
gamma controller assembly can be configured to exclude measurements
or disqualify measurements based on the conditions at the time. For
example, if a high shock (triboluminescence) event occurs, the
assembly could suspend measurement or disqualify measurements for a
given time period during or near the shock event. Other events may
also suspend measurement, another example might be when other
operations are being performed by the measurement while drilling
tool or other downhole tools that could potentially give off
electrical noise, the multiple gamma controller assembly can be
notified before such an event occurs or be programmed with
algorithms to detect such an event through sensor measurement or
other methods. High temperature events can also receive similar
treatment. The conditions which trigger these events are
programmable and can vary based on the probes being used and their
particular sensitivities.
[0045] Another example of a more complex algorithm involves the
identification of a possible third failure mode, one where gamma
probes are outputting measurements within high and low boundaries
but where the output values have begun to skew from what would be
considered accurate values. To identify this failure mode, a gamma
probe health algorithm was developed that compares the statistical
properties of multiple gamma probes to determine if one is
beginning to fail. Similarly, this algorithm can be used by
comparing known good or example data with the output data of one
gamma probe. In an embodiment, this algorithm allows for the gamma
probe health assembly or multiple gamma assembly to select
whichever gamma probe is providing "cleaner" readings during a
given time period, and also allows a gamma probe that is likely
beginning to fail to be identified. Further, this algorithm can
additionally be run on gamma probe output data sets in realtime or
on a delay at the surface or remotely to assess the health of
particular gamma probes or to otherwise qualify and/or disqualify
data that has been collected.
[0046] A potentially failing or malfunctioning gamma probe may
defined as a gamma probe which sporadically outputs inaccurate
counts, but then returns to outputting correct values once the
stress (e.g. elevated temperature and vibration) is reduced. While
a failed gamma probe can be defined as a gamma probe that outputs
inaccurate counts continuously, regardless of the environmental
conditions. It can be useful to identify a potentially failing
probe just as it can be useful to identify a completely failed
gamma probe in that the data output by the potentially failing
probe can be inaccurate or wrong for a given time period. A
potentially failing probe may also fail faster than a well
functioning probe, and therefore it's identification before it
completely fails may be useful.
[0047] A multiple gamma controller assembly can provide two gamma
probe output value logs that should match very closely if both
gamma probes are working correctly. If a probe begins to fail it
may slowly drift apart from the output values collected from the
other probe. The skew can be tracked and compared by calculating a
diversion factor. The diversion factor can be defined as:
D[n-l,n]=K.sub.stdx.sub..sigma.[n-l,n]+K.sub.skewx.sub..gamma.1[n-l,n]+K-
.sub.kurtx.sub..beta.2[n-l,n]
where D is the "differential diversion factor" and K.sub.std,
K.sub.skew, and K.sub.kurt are predetermined weighting factors, n
is the current sample, and l is the window size. Additionally,
x.sub..sigma.[n-l,n] is the standard deviation,
x.sub..gamma.1[n-l,n], is the skew, and x.sub..beta.2[n-l,n] is the
kurtosis of the probability distribution of the samples within the
window defined by [n-l,n], respectively. For example, a moving
window of 60 samples (where each sample is 10 second apart) is used
for the calculations of D below. A higher value of D indicates an
overall lower quality gamma probe (i.e., a noisier and possibly
failing or malfunctioning gamma probe), while a lower D represents
a more stable gamma probe. The differential diversion threshold is
the specific value of D that it would be desirable to stay within.
A differential diversion factor or value outside of the
differential diversion threshold indicates a potentially failing or
malfunctioning gamma probe. The standard deviation a can be defined
as:
.sigma. = 1 N i = 1 N ( x i - .mu. ) 2 ##EQU00001## where
##EQU00001.2## .mu. = 1 N i = 1 N x i ##EQU00001.3##
The standard deviation shows how much variation there is from the
mean, a low standard deviation means that the data points tend to
be close to the mean. The skew is a measure of the extent to which
a probability distribution leans to one side of the mean and can be
defined
as : .gamma. 1 = E ( x - .mu. ) 2 .sigma. 3 ##EQU00002##
The kurtosis .beta..sub.2, is a measure of how outlier prone a
distribution is and can be defined as:
.beta. 2 = E ( x - .mu. ) 4 .sigma. 4 ##EQU00003##
E representing the expected value, and x representing each
individual sample. For example, a sample of five points with an
assumption of an equal probability of each point would be
calculated as:
E ( x - .mu. ) 2 = ( 1 5 ( x 1 - .mu. ) + ( x 2 - .mu. ) + ( x 3 -
.mu. ) + ( x 4 - .mu. ) + ( x 5 - .mu. ) ) 2 ##EQU00004##
[0048] Referring to FIG. 14A, an illustration of raw gamma probe
output values from two gamma probes are shown. FIG. 14B then
illustrates process gamma probe outputs for the raw gamma probe
outputs shown in FIG. 14A, and additionally illustrates the
respective diversion factors for each probe as is shown by the
bolded central lines running through each respective probes
processed and filtered output values. It should be noted that the
weighting factors used in this example were obtained empirically
and are as follows: K.sub.std=4.0, K.sub.skew=1.5, and
K.sub.kurt=1.0. As is shown by the output values for each probe in
this example, the potentially failing probe was returning higher
output values throughout the illustrated time window. As the run
continued, the potentially failing probe drifted higher and
deviated much more than the other gamma probes output values. The
Moving Diversion Integral lines in FIG. 14B were calculated using
the following formula:
D int = 1 T .intg. t 1 t 2 D t ##EQU00005##
where T=t.sub.2-t.sub.1 is the integration time period, and where D
is defined as it was above. The Moving Diversion Integral is
defined by the above equation and is represented by the bolded
lines in FIG. 14B. The integration time used for the values shown
was 120 minutes. The maximum value for the moving integral of the
higher reading gamma probe was 3.71 and was 1.75 for the lower
reading gamma probe. D.sub.diff can be calculated as follows:
D.sub.diff=D.sub.1max-D.sub.2max
where D.sub.1max and D.sub.2max are the maximum diversion factor
values of each probe respectively over the defined time window T.
In this example, if D.sub.diff is positive and outside the bounds
that would be defined as the differential diversion threshold, then
the first gamma probe is potentially failing over the illustrated
time period. If on the other hand, D.sub.diff were negative and
outside the differential diversion threshold then the second gamma
probe would be potentially failing over the illustrated time
period.
[0049] Referring to FIG. 15, a flow chart of an example algorithm
for a gamma probe/sensor requalification process is shown. When a
gamma probe has been disqualified, the microcontroller may run this
or a similar process to determine if the probe might be
requalified. In this example, the system begins requalification 710
and waits for a pre-set but configurable time period 720. After the
time period has passed the next step determines if the gamma probe
outputs are now within the high and low boundaries 730. If the
gamma probe output values are not within bounds the logic returns
to step 720 and again waits for the pre-set but configurable time
period. If the gamma probe output value is within bounds, it is
next determined whether or not the gamma probe output is within the
differential diversion threshold 740, which may be calculated
realtime or preset as was discussed previously. If the gamma probe
output value is not within bounds of the differential diversion
threshold, the logic returns to step 720 and again waits for the
pre-set but configurable time period. If the gamma probe output
value is within the differential diversion threshold bounds, it is
next determined whether or not the gamma probe output is within the
cross correlation threshold 740, which may also be calculated
realtime or preset as was discussed previously. If the gamma probe
output value is not within bounds of the cross correlation
threshold, the logic returns to step 720 and again waits for the
pre-set but configurable time period. If the gamma probe output
value is within the cross correlations threshold bounds, the gamma
probe is then re-qualified and that gamma probes measurement output
values can then be trusted by the downhole gamma probe health
detection assembly and treated accordingly.
[0050] Referring to FIG. 16, a flow chart of an example algorithm
for a gamma health monitoring process is shown. In this example,
the system begins gamma probe health monitoring 810 and run through
any initialization steps for the gamma health algorithm 720. The
one or more gamma probe module measurement outputs are taken 830.
The measurement for each module configured is then determined to be
within or outside of a configurable upper boundary 840. If the
gamma probe output is determined to not be within the upper
boundary an upper boundary timeout period is entered 842 at least
in regard to the processing of that particular gamma probes output
values. If the gamma probe output is within the upper boundary it
is then determined to be within or outside of a configurable lower
boundary 850. If the gamma probe output is determined to not be
within the lower boundary a lower boundary timeout period is
entered 852 at least in regard to the processing of that particular
gamma probes output values. If the gamma probe output is within the
lower boundary differential diversion is then calculated in
realtime or determined from a table of known or previously
calculated differential diversion values for that probe or probe
type 860. If a gamma probe output was outside a boundary, such as
in steps 842 and 852, and the timeout period has ended for that
particular probe, that probe is then checked again to determine if
its output is within upper and lower boundaries 864. If that gamma
probes output is back within bounds, it is then flagged or marked
as good or trusted again 862 and then a differential diversion
factor may be calculated 860. Once a differential diversion factor
is calculated or determined, as previously discussed, the
differential diversion is then determined to be within or outside
of a differential diversion threshold. As long as the one or more
gamma probe output values are within the differential diversion
threshold, the gamma probe measurements are taken again 830, and
this process continues to repeat itself. If the differential
diversion for a particular probe is determined to not be within the
differential diversion threshold, a configurable timeout period is
entered before the gamma probe output values from that probe are
treated as trusted again 872. The differential diversion for that
probe is then tested as to whether or not it is back within bounds
874. If the differential diversion is back in bounds, the probe is
re-qualified or treated as trusted again and gamma module outputs
are read again 830. If the differential diversion factor for that
particular probe is still out of bounds, then the differential
diversion factor is checked against the cross correlation threshold
876. Of the probe is within that threshold then readings can again
be taken from that probe. If the probe is outside of the cross
correlation threshold, the respective probe is flagged and more
permanently disqualified as malfunctioning probe 880.
[0051] Referring to FIG. 17, a flow chart for a gamma output
process 900 where a gamma health process and a gamma
requalification process are included in the gamma output process is
shown. In this example, the system begins by powering on the gamma
probe health controller assembly and any included gamma probes 910.
A determination is then made as to whether a first gamma probe is
flagged as bad in memory 920. If the first gamma probe is flagged
as bad in memory, it is determined if the second gamma probe is
flagged as good or bad in memory and if so, the second gamma probes
output data is collected 922. Requalification is run on the first
gamma probe if it has been previously flagged as bad 924. If the
first gamma probe is not flagged as bad in memory the first gamma
probes output is collected 930. The gamma health algorithm based on
the calculation of a diversion factor as outlined above is then run
once the outputs of multiple gamma probes have been collected 940.
Next, it is determined if either gamma probe should be or has been
flagged as bad 950. If no gamma probe that is being compared has
been flagged as bad, then it is determined if the gamma probe
output values are within the configurable lower differential
diversion threshold 952. If it is determined that one or more
probes is not within the lower differential diversion threshold
then a lower differential diversion threshold miss timeout occurs
920. During this timeout a configurable period of time is set
waited through before a determination is made on the particular
probes being compared. Going back to step 950, if any of the gamma
probes are flagged as bad then the remaining "good gamma" probes
output value is utilized. This can mean that the "good gamma"
probes output is written to a memory log downhole or sent to the
surface for logging and/or use. A requalification determination is
then made on any gamma probes determined to be or flagged as "bad"
970. Going back to step 952, if it is determined that both or all
gamma probe outputs are currently within the lower differential
diversion threshold, then the tool will utilize and log of send
uphole the current gamma probe being output. Optionally, if both or
all gamma probes being utilized are within the lower differential
diversion threshold then the gamma probe output values can be
averaged or otherwise combined in an embodiment where one gamma
probe output is needed. Optionally as well, both gamma probe output
values can be logged with a trusted flag. Similarly, when gamma
probes have been determined as bad or flagged for any reason, there
data can still be logged with a trusted flag unset or another flag
indicating the reason the gamma probes output data values are not
being trusted at that particular time. If after the timeout of step
920, it is determined that the output data of both or all of the
gamma probes is back within the lower differential diversion
threshold 964, then the gamma probe output data can be logged or
sent uphole according to the current output configuration of the
tool 962. If after the timeout, it is determined that a particular
gamma probes output is still out of bounds of the lower
differential diversion threshold, then the tool can switch to
routinely outputting or logging as trusted the gamma probe output
data of another probe 966. Additionally, regarding steps 952, 920,
and 964, additional similar steps can be run and added to this
algorithm that relate to the configurable and calculated higher
differential diversion threshold.
[0052] Each of the steps and sub-steps of the example embodiments
described in FIGS. 15-17 can be configured to either be run and be
a part of an algorithm or can be configured to not be run and not
be part of an algorithm.
[0053] In addition to calculating the differential diversion factor
downhole by an assembly having a micro-controller or other type of
processor, it should be understood that probe output values could
be sent to the surface for realtime or delayed calculation of the
differential diversion factor at the surface or even at remote
sites via post processing. Further, the calculated differential
diversion factors could be sent to the surface themselves, at which
point the various comparisons, qualifications, assessments, and any
other post processing can be performed. The flowcharts of FIGS.
15-17 contain various steps which can generally be split between
the downhole controller assembly and a computer or microcontroller
assembly at the surface in terms of what steps and what
calculations are being performed where. Offsite processing can
additionally be a part of realtime or delayed data collection
efforts, with some of the calculations and steps outlined above and
in the flowcharts of FIGS. 15-17 being performed away from the
wellsite. Particularly where a single gamma probe is run downhole
to collect data, the data collected might more ideally be compared
to known good or example data in a post processing environment
between runs downhole. Additionally, when data is being collected
from multiple gamma probes downhole, data might again more ideally
be pulled from the tool itself at the surface, at which time
post-processing can be run to calculate the differential diversion
factors over various time periods and generally post-qualify the
data that was collected. An offsite computer can be utilized to
post-process the gamma probe output data and compare gamma probe
output data from multiple probes. The data collected by the probe
in any of the mentioned embodiments can either be sent to the
surface while the tool is located downhole or collected from the
tool by a USB cable, serial connection, parallel connection, or
other common bus when the tool is back at the surface or at a
remote site. Differential diversion factors can also be calculated
downhole without storing the calculation data to a log or memory.
This embodiment preserves available memory for gamma probe output
data while still enabling the running of advanced failure detection
algorithms. Further in this embodiment, the data will send a flag
to the surface or log relevant information to memory only when the
data detects a potentially bad gamma probe.
[0054] To assist with failure analysis when the tool is being
serviced, the multiple gamma controller assembly can log several
relevant parameters of the gamma controller assembly or of other
components of the tool as it is operating. There are at least two
classifications of events that can be logged: time-based logs and
event-based logs. Time-based logs can include parameters that are
logged periodically regardless of what is happening with the tool.
Examples of this include temperature, battery voltages, motor bus
voltage, axial vibration, lateral vibration, moving average of the
counts from each gamma probe, etc. Event-based logs can include
specific events that may occur, including axial or lateral shock
events, as monitored by the accelerometers or other similar
sensors, changes in the state of the flow signal, changes in the
state of the pulse line, the duration of a pulse event, etc.
[0055] In an embodiment, the multiple gamma controller can be
configured with "high-g" and "low-g" accelerometers to measure
shock and vibration measurements. Generally, shock can be
considered events above 25 G, and can be recorded along with other
information, such as time, date, and other sensor values. Recording
the number of shock events provides a good predictor of a
particular type of drilling environment and allows the prediction
of the remaining lifetime of the multiple gamma assembly for a
certain number of gamma probes in that type of environment or at
that particular wellsite. If a shock is recorded above a very high
threshold, immediate replacement of the crystal and photomultiplier
assembly can be considered as they may be very close to failure if
not already malfunctioning. Messages can be sent by the
microcontroller through the measurement while drilling tool
interface or separately to the surface to alert operations
personnel. The same considerations can be applied to vibration
measurement by the "low-g" accelerometers. The multiple gamma
assembly can be configured such that down-hole vibration levels can
be continuously calculated and logged to memory. Additionally the
multiple gamma assembly can also be configured with on-board
temperature sensors and the complete temperature profile history
may be tracked since high temperatures also place very high stress
on the board. Thresholds may be set for temperature events and
similarly to gamma failure, shock, or vibration events, messages
can be sent to the surface through the measurement while drilling
tool interface or through a separate interface to the surface.
[0056] In another embodiment, event "odometers" can be setup to
tack the various tool health indicators, such as the various sensor
values, as previously mentioned. The odometers may accumulate value
as separate, shock, vibration, and temperature odometers, and
provide an idea to the tool operators of the general abuse a
particular tool has taken. This may be useful to determine and
improve upon common modes of failure for a particular tool design.
For example, it may be found that tools with a certain level on
their vibration odometers are likely fail within a calculated
timeframe based on tool data compiled over time. Vibration
odometers can be configured to represent total time spent at
vibration levels corresponding to bin divisions. Temperature
odometers can be configured to represent total time spent at
temperature levels corresponding to bin divisions. Odometers can
optionally be reset when the multiple gamma controller assembly is
paired with different gamma probes or when the multiple gamma
controller circuit board is replaced.
[0057] In an embodiment, the gamma health detection assembly can be
configured to apply individual calibrations for each gamma probe,
optionally applying the calibrations before averaging or
determination operations are performed. The averaged or calculated
values can be transmitted to the measurement while drilling tool as
synthesized voltage pulses as well as through the generic variable
communication mean available, such as by a serial port
communication to the measurement while drilling tool. The
measurement while drilling tool is programmed with a calibration of
1.0 (multiplier) so as not to skew the data calculated by the
multiple gamma controller assembly, for a given embodiment.
[0058] These logs allow the failures of the gamma probes to be
analyzed and improve future operational guidelines to help prevent
future failures of gamma probes downhole. Additionally, these logs
allow predictive maintenance to be performed by preemptively
replacing gamma probes that are likely to fail soon, before a
downhole failure occurs. Gamma probes are generally constructed by
pairing NaI(TI) (Sodium Iodide/Thalium) crystals with
photomultiplier tubes. The probes also often have high voltage
supply circuitry and a discriminator circuit integrated as well.
Each component and the paired assembly have inherent structural
weaknesses and can malfunction when exposed by the harsh conditions
of a drilling environment. The gamma probe components are very
temperature, vibration and shock sensitive, and often break
irreparably in the drilling environment. In addition, the
photo-multiplier has glass components, which are particularly
sensitive to vibration and shock.
[0059] In an embodiment and as an example, a gamma probe can be
configured to produce a pulse when a gamma wave/particle emitted
from a geological formation comes into contact with the NaI(TI)
crystal of the gamma probe. When collision occurs, a photon is
produced. A hermetically sealed enclosure of the crystal is
internally reflective, and will guide the photon out of one open
end of the crystal, which can be configured with a clear glass
lens. The photon will travel out of the crystal, through the
optical lens, and into a photomultiplier tube of the gamma probe.
When the photon strikes a particular surface of the photomultiplier
tube, an electrical current pulse is generated. The photomultiplier
tube's purpose is to convert the photon into electrical energy so
that it can be sent to and interpreted/read by the microcontroller
circuitry of the multiple gamma controller assembly. A high voltage
power supply is required to operate the photomultiplier tube. For
example, photomultiplier tubes often require voltages around 1500V
DC. Other gamma probe designs can be substituted for this design in
the embodiments described.
[0060] Although the concepts disclosed herein have been described
in connection with the preferred form of practicing them and
modifications thereto, those of ordinary skill in the art will
understand that many other modifications can be made thereto.
Accordingly, it is not intended that the scope of these concepts in
any way be limited by the above description.
* * * * *