Formation evaluation utilizing dual wait time nuclear magnetic resonance

Patent metadata

Field	Value
Publication number	US-2016116629-A1
Application number	US-201514920436-A
Country	US
Kind code	A1
Filing date	Oct 22, 2015
Priority date	Oct 23, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

A system for measuring a property of fluid in an earth formation includes a downhole tool disposed in a borehole and configured to be movable within the borehole and a nuclear magnetic resonance (NMR) measurement device including a transmitter configured to emit at least two pulse trains of magnetic energy into the earth formation and a detector configured to detect a long-TW echo train and a short-TW echo train resulting from the at least two pulse trains. The system also includes a processor configured to combine the information from the at least two pulse trains and a rate of penetration of the downhole tool to form a measurement of the property.

First claim

What is claimed is:

1 . A system for measuring a property of an earth formation, the system comprising:
a downhole tool disposed in a borehole and configured to be movable within the borehole; a nuclear magnetic resonance (NMR) measurement device including a transmitter configured to emit at least two pulse trains with different wait times (TW) into the earth formation and a detector configured to detect a long-TW echo train and a short-TW echo train resulting from the at least two pulse trains; and a processor configured to combine the information from the at least two echo trains and a speed of axial motion of the downhole tool to perform a measurement of the property.

2 . The system of claim 1 , wherein the wait time of at least one of the pulse trains is predetermined.

3 . The system of claim 2 , wherein the processor determines NMR data.

4 . The system of claim 3 , wherein the NMR data has an outflow correction applied thereto.

5 . The system of claim 2 , wherein the processor:
stacks and/or averages the echo trains received during NMR measurements; and transforms the NMR data from the time domain into the T2 domain to form a T2 distribution for the long-TW echo train and a T2 distribution for the short-TW echo train.

6 . The system of claim 5 , wherein the processor forms an amplitude ratio of at least a part of the T2 distribution for the long-TW echo train and at least a part of the T2 distribution for the short-TW echo train.

7 . The system of claim 2 , wherein the processor forms an estimate for T1.

8 . The system of claim 2 , wherein the processor computes polarization data for at least one of the long-TW echo train and short-TW echo train.

9 . The system of claim 8 , wherein the processor:
computes a polarization ratio based on at least a part of the polarization data; and computes T1 from the polarization ratio.

10 . The system of claim 9 , wherein:
the processor determines a polarization curve from at least a part of the polarization data; and at least a part of the polarization curves is averaged.

11 . A method for measuring a property of an earth formation, the method comprising:
disposing a downhole tool in a borehole; emitting with a nuclear magnetic resonance (NMR) measurement device at least two pulse trains with different wait times TW into the earth formation; detecting with a detector on the NMR device a long-TW echo train and a short-TW echo train resulting from the at least two pulse trains; and combining the information from the at least two echo trains and a speed of axial motion of the downhole tool to perform a measurement of the property.

12 . The method of claim 11 , wherein the wait time of at least one of the pulse trains is predetermined.

13 . The method of claim 12 , wherein combining includes determining NMR data.

14 . The method of claim 13 , wherein the NMR data has an outflow correction applied thereto.

15 . The method of claim 12 , wherein combining further includes:
stacking and/or averaging the echo trains received during NMR measurements; and transforming the NMR data from the time domain into the T2 domain to form a T2 distribution for the long-TW echo train and a T2 distribution for the short-TW echo train.

16 . The method of claim 15 , wherein combining includes forming an amplitude ratio of at least a part of the T2 distribution for the long-TW echo train and the T2 distribution for the short-TW echo train.

17 . The method of claim 11 , wherein combining includes:
forming an estimate for T1.

18 . The method of claim 11 , wherein combining includes computing polarization data for at least one of the long-TW echo train and the short-TW echo train.

19 . The method of claim 18 , wherein combining includes:
computing a polarization ratio based on at least a part of the polarization data; and computing T1 from the polarization ratio.

20 . The method of claim 19 , wherein combining includes determining a polarization curve from at least a part of the polarization data; and
at least a part of the polarization curves is averaged.

Assignees

• Coman Radu
• Tietjen Holger
• Thern Holger F
• Blanz Martin
• Baker Hughes Inc

Inventors

• Coman Radu
• Tietjen Holger
• Thern Holger F
• Blanz Martin

Classifications

• G01V3/40

  specially adapted for measuring magnetic field characteristics of the earth · CPC title

• G01V3/38

  Processing data, e.g. for analysis, for interpretation, for correction · CPC title

• G01V3/32 Primary

  operating with electron or nuclear magnetic resonance · CPC title