Correction Of Motion Effect In Nuclear Magnetic Resonance (NMR) Logging

Patent metadata

Field	Value
Publication number	US-2016202384-A1
Application number	US-201414914193-A
Country	US
Kind code	A1
Filing date	Aug 21, 2014
Priority date	Aug 25, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

A method for correcting motion-effects from a downhole measurement includes, in one embodiment, determining relative motion of a downhole logging tool for a given logging operation in a borehole formed in an earth formation, determining a motion induced signal decay (MID) based upon the determined relative motion, determining a motion-effect inversion kernel (MEK) based upon the determined MID, using the downhole logging tool to acquire measurements that are affected by motion of the downhole logging tool during the logging operation, and using the MEK to process the acquired motion-affected measurements to obtain motion-corrected data. Corresponding systems, devices, and apparatuses are also disclosed herein.

First claim

What is claimed is:

1 . A method comprising:
determining relative motion of a downhole logging tool for a given logging operation in a borehole formed in an earth formation; determining a motion induced signal decay (MID) based upon the determined relative motion; determining a motion-effect inversion kernel (MEK) based upon the determined MID; using the downhole logging tool to acquire measurements that are affected by motion of the downhole logging tool during the logging operation; and using the MEK to process the acquired motion-affected measurements to obtain motion-corrected data.

2 . The method of claim 1 , wherein the relative motion is determined using at least one motion measurement sensor located on the downhole logging tool.

3 . The method of claim 2 , wherein the at least one motion measurement sensor comprises at least one of an accelerometer, a magnetometer, a gyroscope, a caliper, or any combination thereof.

4 . The method of claim 2 , wherein the at least one motion measurement sensor is located proximate an antenna of the downhole logging tool.

5 . The method of claim 4 , wherein the downhole logging tool comprises a nuclear magnetic resonance (NMR) logging tool.

6 . The method of claim 5 , wherein the NMR logging tool comprises a logging-while-drilling (LWD) NMR logging tool.

7 . The method of claim 1 , wherein the downhole logging tool comprises a nuclear magnetic resonance (NMR) logging tool.

8 . The method of claim 7 , wherein motion-affected measurements comprise spin echoes obtain in response to a pulse sequence applied to a excited region of the earth formation.

9 . The method of claim 7 , wherein the motion-corrected data comprises a motion-corrected T 1 distribution or a motion-corrected T 2 distribution.

10 . The method of claim 1 , wherein the downhole logging tool is part of a bottom hole assembly (BHA) of a drill string, and wherein the relative motion data is obtained by modeling transient dynamic behavior of the BHA.

11 . The method of claim 10 , wherein the modeling comprises calculating interactions between the BHA and rock surfaces within the borehole for given drilling parameters and formation properties.

12 . The method of claim 10 , wherein motion data from one or more motion measurement sensors is used on conjunction with the modeling of the transient dynamic behavior of the BHA to obtain the relative motion data.

13 . The method of claim 1 , wherein determining the MID based upon the determined relative motion comprises performing nuclear spin dynamics simulation.

14 . The method of claim 13 , wherein performing the nuclear spin dynamics simulation comprises, for a plurality of vector maps each corresponding to a respective one of a plurality of time steps, calculating for each voxel of each vector map a spin dynamic as a function of a time-varying magnetic field.

15 . The method of claim 14 , wherein the time-varying magnetic field comprises a static magnetic field (B 0 ) and/or an oscillating magnetic field (B 1 ).

16 . The method of claim 14 , wherein the plurality of vector maps comprises a set of vector maps for spin rotations, a set of vector maps for B 0 , and a set of vector maps for B 1 , and wherein the spin rotation at each voxel of the spin rotation vector maps are calculated based on corresponding voxels in the B 0 and/or B 1 vector maps.

17 . The method of claim 1 , wherein determining the MID based upon the determined relative motion comprises determining net relative displacement of the downhole logging tool.

18 . The method of claim 1 , wherein the MEK comprises a time constant of the MID that is represented by exponential decay.

19 . A system comprising:
a downhole logging tool that, when deployed in a borehole, acquires measurements of a formation surrounding the borehole, the acquired measurements being affected due to lateral motion of the downhole logging tool during acquisition of the measurements; and a processing device configured to perform an inversion on the motion-affected measurements to obtain motion-corrected data representative one or more properties of the formation using a motion-effect kernel (MEK), wherein the MEK is derived based on a motion induced signal decay (MID) determined based on a known relative motion of the downhole logging tool.

20 . The system claim 19 , wherein the downhole logging tool comprises at least one motion measurement sensor.

21 . The system of claim 20 , wherein the at least one motion measurement sensor comprises at least one of an accelerometer, a magnetometer, a gyroscope, a caliper, or any combination thereof.

22 . The system of claim 20 , wherein the at least one motion measurement sensor is located proximate an antenna of the downhole logging tool.

23 . The system of claim 22 , wherein the downhole logging tool comprises a nuclear magnetic resonance (NMR) logging tool.

24 . The system of claim 23 , wherein the NMR logging tool comprises a logging-while-drilling (LWD) NMR logging tool.

25 . The system of claim 19 , wherein the downhole logging tool comprises a logging-while-drilling (LWD) NMR logging tool.

26 . The system of claim 25 , wherein the motion-affected measurements comprise spin echoes obtain in response to a pulse sequence applied to a excited region of the earth formation, and wherein the motion-corrected data comprises a motion-corrected T 1 distribution or a motion-corrected T 2 distribution.

27 . The system of claim 19 , wherein the downhole logging tool is part of a bottom hole assembly (BHA) of a drill string, and wherein the relative motion data is obtained by modeling transient dynamic behavior of the BHA.

28 . The system of claim 27 , wherein the modeling comprises calculating interactions between the BHA and rock surfaces within the borehole for given drilling parameters and formation properties.

29 . The system of claim 19 , wherein the relative motion of the downhole logging tool is determined using at least one of a transient dynamic behavior modeling, fluid dynamics model, a particle dynamics model, or a net transport model, or a combination thereof.

30 . The system of claim 19 , wherein MID is determined based upon the relative motion of the downhole logging tool by using a nuclear spin dynamics simulation.

31 . The system of claim 19 , wherein the processor is a surface processor.

32 . A method for correcting downhole measurements affected by tool motion as substantially described herein.

33 . The method of claim 32 , wherein the downhole measurements comprise NMR measurements.

34 . A system for correcting downhole measurements affected by tool motion as substantially described herein.

Assignees

• Schlumberger Technology Corp

Inventors

• Utsuzawa Shin
• Hurlimann Martin
• Zielinski Lukasz
• Zhang Haitao

Classifications

• E21B17/10

  Wear protectors; Centralising devices {, e.g. stabilisers} · CPC title

• G01V3/32

  operating with electron or nuclear magnetic resonance · CPC title

• G01V3/14

  operating with electron or nuclear magnetic resonance · CPC title

• E21B47/024 Primary

  of devices in the borehole (determining slope or direction of the borehole E21B47/022) · CPC title

• G01V3/18

  specially adapted for well-logging · CPC title