Multi-step borehole correction scheme for multi-component induction tools

Patent metadata

Field	Value
Publication number	US-2016274263-A1
Application number	US-201615169423-A
Country	US
Kind code	A1
Filing date	May 31, 2016
Priority date	Mar 31, 2010
Publication date	Sep 22, 2016
Grant date	—

Abstract

Various resistivity logging tools, systems, and methods are disclosed. At least some system embodiments include a logging tool and at least one processor. The logging tool provides transmitter-receiver coupling measurements that include at least direct coupling along the longitudinal tool axis (Czz), direct coupling along the perpendicular axis (Cxx or Cyy), and cross coupling along the longitudinal and perpendicular axes (Cxz, Cyz, Czx, or Czy). The processor performs a multi-step inversion of said transmitter-receiver coupling measurements to obtain values for model parameters. Based at least in part on the model parameters, the processor determines borehole corrections for the transmitter-receiver coupling measurements and may further provide one or more logs derived from the borehole corrected transmitter-receiver coupling measurements. In at least some embodiments the logging tool assembly further collects borehole size measurements and measurements of borehole fluid resistivity for use in performing the inversion and determining the borehole corrections.

First claim

1 . A logging method that comprises:
conveying a logging tool along a borehole through a formation to gather multi-component transmitter-receiver coupling measurements; performing a multi-step inversion of the multi-component coupling measurements to obtain values for model parameters, the multi-step inversion including:
adjusting horizontal conductivity or resistivity of the formation to reduce a mismatch between a measured and predicted direct coupling along a longitudinal tool axis;
after said adjusting the horizontal conductivity or resistivity, adjusting vertical conductivity or resistivity of the formation to reduce a mismatch between a measured and predicted direct coupling along a tool axis perpendicular to the longitudinal tool axis; and
after said adjusting the vertical conductivity or resistivity, adjusting eccentricity displacement d ecc to reduce a mismatch between a measured and predicted cross-coupling along the longitudinal and perpendicular tool axes;
determining borehole corrected values for said multi-component transmitter receiver coupling measurements based at least in part on said model parameters; and displaying a log based at least in part on at least one of said borehole corrected values.

2 . The method of claim 1 , wherein said logging tool also collects borehole size measurements during said conveying.

3 . The method of claim 2 , wherein said logging tool further collects measurements of borehole fluid resistivity during said conveying.

4 . The method of claim 1 , wherein said performing a multi-step inversion includes preprocessing the transmitter-receiver coupling measurements with an adaptive low-pass filter.

5 .- 8 . (canceled)

9 . The method of claim 1 , wherein said determining includes:
predicting multi-component transmitter-receiver coupling measurements with and without a borehole; calculating differences between the predicted measurements with and without the borehole to determine borehole corrections; and applying the borehole corrections to the gathered multi-component transmitter-receiver coupling measurements to obtain said borehole corrected values.

10 . A logging system that comprises:
a logging tool having a longitudinal tool axis and a perpendicular tool axis, the tool having an antenna arrangement that provides, as a function of tool position in a borehole, transmitter-receiver coupling measurements that include at least direct coupling along the longitudinal tool axis (Czz), direct coupling along the perpendicular axis (Cxx), and cross coupling along the longitudinal and perpendicular axes (Cxz); at least one processor that:
performs a multi-step inversion of said transmitter-receiver coupling measurements to obtain values for model parameters, the multi-step inversion including:
adjusting horizontal conductivity or resistivity to reduce a mismatch between a measured and predicted direct coupling along a longitudinal tool axis (Czz);
after said adjusting the horizontal conductivity or resistivity, adjusting vertical conductivity or resistivity to reduce a mismatch between a measured and predicted direct coupling along a tool axis (Cxx) perpendicular to the longitudinal tool axis; and
after said adjusting the vertical conductivity or resistivity, adjusting eccentricity displacement d ecc to reduce a mismatch between a measured and predicted cross-coupling along the longitudinal and perpendicular tool axes (Cxz);

determines borehole corrected values for said transmitter-receiver coupling measurements based at least in part on said model parameters; and
provides a log based at least in part on at least one of said borehole corrected values.

11 . The system of claim 10 , wherein the processor is coupled to a user interface to display said log.

12 . The system of claim 10 , wherein the logging tool further provides borehole size measurements.

13 . The system of claim 10 , wherein the logging tool further provides measurements of borehole fluid resistivity.

14 . The system of claim 10 , wherein as part of performing the multi-step inversion, the at least one processor applies a low-pass filter to said transmitter-receiver coupling measurements.

15 .- 18 . (canceled)

19 . The system of claim 10 , wherein as part of said determining, the at least one processor:
predicts multi-component transmitter-receiver coupling measurements with and without a borehole; differences the predicted measurements with and without the borehole to determine borehole corrections; and applies the borehole corrections to the multi-component transmitter-receiver coupling measurements provided by the logging tool.

20 . The method of claim 1 , wherein the model parameters are for a vertical borehole model.

21 . The method of claim 1 , wherein the logging tool includes receiver antennas at different distances from a transmitter antenna.

22 . The method of claim 1 , wherein the logging tool is a logging while drilling tool that is conveyed along the borehole as part of a drill string.

23 . The method of claim 1 , wherein the logging tool is conveyed along the borehole with a wireline.

24 . The system of claim 10 , wherein the model parameters are for a vertical borehole model.

25 . The system of claim 10 , wherein the logging tool includes receiver antennas at different distances from a transmitter antenna.

26 . The system of claim 25 , wherein the logging tool includes a tilted transmit antenna and two pairs of tilted receive antennas.

27 . The system of claim 10 , wherein the logging tool is a logging while drilling tool that is conveyed along the borehole as part of a drill string.

28 . The system of claim 10 , wherein the logging tool is conveyed along the borehole with a wireline.

Assignees

• Halliburton Energy Services Inc

Inventors

• Hou Junsheng
• Bittar Michael S

Classifications

• G01V3/26 Primary

  operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30) · CPC title

• G01V3/28 Primary

  using induction coils · CPC title

• F15B15/14

  of the straight-cylinder type · CPC title

• G01V3/30

  operating with electromagnetic waves · CPC title

• B23D31/00

  Shearing machines or shearing devices covered by none or more than one of the groups B23D15/00 - B23D29/00; Combinations of shearing machines · CPC title