LWD resistivity imaging tool with adjustable sensor pads

Patent metadata

Field	Value
Publication number	US-9790787-B2
Application number	US-201314403966-A
Country	US
Kind code	B2
Filing date	Aug 30, 2013
Priority date	Aug 30, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A logging while drilling tool for measuring a geological formation surrounding a wellbore includes a tool body having one or more sensor pads. Each sensor pad is coupled to the tool body by an extendable coupling that is operable to adjust the radial position of the sensor pad by extending away from or retracting toward the tool body. One or more sensors are mounted to each sensor pads and the sensors are operable to obtain a measurement a property of the formation. The tool also includes a downhole control unit having a transmitter and receiver. The downhole control unit is operable to receive the measurement and transmit the measurement to a surface controller, wherein the transmitted measurement indicates a measurement resolution.

First claim

We claim:

1. A tool for measuring a geological formation surrounding a wellbore, the tool comprising:
a tool body;
one or more sensor pads, each sensor pad being coupled to the tool body by an extendable coupling, each coupling being operable to adjust the radial position of the sensor pad by extending both away from and retracting toward the tool body;
one or more sensors, each sensor being mounted to one of the sensor pads and operable to obtain a measurement of a property of the formation; and
a downhole control unit comprising a transmitter and a receiver, the downhole control unit being operable to receive the measurement and transmit the measurement to a surface controller, wherein the transmitted measurement indicates a measurement resolution, wherein the downhole control unit is further operable to receive a control signal from the surface controller based on the measurement resolution, and to extend or retract the sensor pad in response to the control signal.

2. The tool of claim 1 , wherein the extendable coupling comprises a biasing spring.

3. The tool of claim 1 , where in the extendable coupling comprises a hydraulic piston.

4. The tool of claim 1 , wherein the extendable coupling comprises a motorized extension arm.

5. The tool of claim 4 , wherein the one or more sensor pads comprise one or more wearable pads and wherein each sensor is embedded within one of the wearable pads and offset from the outer surface of the wearable pad.

6. The tool of claim 5 , wherein each of the sensors comprises a sensor selected from the group consisting of: an electrode, a geophone, and a gamma radiation sensor.

7. A method for forming an image of a geological formation surrounding a wellbore comprising:
deploying an imaging tool into the wellbore, the imaging tool comprising a tool body and one or more sensor pads, each sensor pad having a sensor and being coupled to the tool body by an extendable coupling, wherein each extendable coupling is operable to both extend the sensor pad away from and retract the sensor pad toward the tool body;
transmitting a sensor signal to a surface controller;
receiving the sensor signal at the surface controller;
determining the resolution of the sensor signal; and
transmitting a command to the imaging tool to extend or retract the sensor pad based on whether the resolution of the sensor signal is above or below a predetermined value.

8. The method of claim 7 , which the sensor signal comprises a mud pulse telemetry signal.

9. The method of claim 7 , wherein the sensor signal comprises a resistivity measurement.

10. The method of claim 7 , wherein the sensor signal comprises a signal from a geophone.

11. The method of claim 7 , wherein determining the resolution of the sensor signal comprises:
receiving a plurality of sensor signals;
compiling the plurality of sensor signals to form an image of the formation; and
determining whether the resolution of the image is above or below a predetermined threshold.

12. The method of claim 7 , wherein transmitting a command to the imaging tool to extend or retract the sensor panel comprises transmitting a command to a hydraulic piston that extends or retracts the sensor pad in response to receiving the command.

13. The method of claim 7 , wherein transmitting a command to the imaging tool to extend or retract the sensor panel comprises transmitting a command to a motorized extension mechanism that extends or retracts the sensor pad in response to receiving the command.

14. A system for generating an image of a geological formation surrounding a wellbore, the system comprising:
a surface controller;
a drill string;
an imaging tool comprising a tool body, a plurality of sensors embedded within sensor pads coupled to the tool body by extendable couplings, and a downhole control unit communicatively coupled to the sensors, extendable couplings, and the surface controller,
wherein each coupling is operable to adjust the radial position of the sensor pad by both extending the sensor pad away from and retracting the sensor pad toward the tool body;
wherein each sensor is operable to obtain a measurement of a property of the formation, the measurement indicating a measurement resolution;
wherein the downhole control unit is operable to receive the measurement and transmit the measurement to the surface controller; and
wherein the downhole control unit is further operable to receive a control signal from the surface controller based on the measurement resolution, and to extend or retract the sensor pad in response to the control signal.

15. The system of claim 14 , wherein the downhole control unit transmits the command to the extendable couplings to dynamically extend or retract the sensor pads based on whether the resolution of the imaging sensor signal is above or below a predetermined threshold.

16. The system of claim 14 , wherein the surface controller comprises a comparator, and wherein:
the surface controller is configured to receive a plurality of imaging signals and compile the imaging signals to form an image, the image being indicative of a cross-section of the geological formation; and
the surface controller is further configured to determine a resolution of the image, determine whether the image resolution is above or below a predetermined threshold, and generate a command to extend or retract the extendable couplings based on whether the image resolution is above or below the predetermined threshold.

17. The system of claim 14 , wherein the imaging sensors comprise electrodes and wherein the image comprises a resistivity image.

18. The system of claim 14 , wherein the imaging sensors comprise geophones, and wherein the image comprises a seismic image.

Assignees

• Halliburton Energy Services Inc

Inventors

• Parker Timothy James

Classifications

• G01V11/005

  Devices for positioning logging sondes with respect to the borehole wall (centralising devices for drilling rods or pipes E21B17/10; setting or locking tools in boreholes E21B23/00; locating objects in boreholes E21B47/09) · CPC title

• G01V1/46

  Data acquisition · CPC title

• G01V1/181

  Geophones · CPC title

• G01V3/20

  operating with propagation of electric current · CPC title

• E21B47/01 Primary

  Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like · CPC title