Cation exchange capacity and water saturation from array induction data

Patent metadata

Field	Value
Publication number	US-10215876-B2
Application number	US-201615286776-A
Country	US
Kind code	B2
Filing date	Oct 6, 2016
Priority date	Oct 6, 2016
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

In-phase and quadrature components have different relationships with some important petrophyscial parameters, such as water saturation and mineral cation exchange capacity (CEC). In clay-containing subterranean rock formation such as shaly sand formations, these parameters can be estimated using different components of array induction tool data combined with other knowledge about the clay-containing formation. Some parameters, such as mobility and fraction of counterions are valid in cases where the pore water solution is an electrolyte of NaCl.

First claim

What is claimed is:

1. A method of estimating parameters for a clay-containing subterranean rock formation comprising:
positioning a tool in a borehole traversing the clay-containing formation, the tool comprising one or more transmitter coils and a plurality of receiver coils;
inducing alternating current loops in the clay-containing formation using the one or more transmitter coils;
measuring a signal resulting from the induced current loops using the receiver coils;
combining measurements from the receiver coils and knowledge about the clay-containing formation to obtain an estimate of water saturation in the formation and an estimate of cation exchange capacity in the formation; and
wherein the estimate of water saturation in the formation and the estimate of cation exchange capacity are obtained using a first relationship between real conductivity and a first plurality of formation parameters and a second relationship between complex conductivity and a second plurality of formation parameters.

2. The method of claim 1 wherein the first and second pluralities of formation parameters both comprise water saturation and the estimate of cation exchange capacity.

3. The method of claim 2 wherein the first plurality of formation parameters further comprises: water conductivity, grain density; mobility of counterions; and an electric formation factor.

4. The method of claim 3 wherein said water conductivity is calculated using water salinity and temperature.

5. The method of claim 4 wherein said water salinity is estimated using borehole water samples.

6. The method of claim 5 wherein said temperature and said grain density are obtained from temperature and laboratory density measurement data.

7. The method of claim 2 wherein the second plurality of formation parameters further comprises: grain density; a fraction of counterions in a Stern layer; and mobility of counterions within the Stern layer.

8. The method of claim 1 wherein said knowledge about the formation is obtained from laboratory measurements and/or measurement logs.

9. The method of claim 8 wherein said measurement logs include a laboratory density measurement and a temperature log from which temperature and grain density is obtained.

10. The method of claim 1 wherein the clay-containing subterranean rock formation is a shaly-sand formation.

11. The method of claim 1 wherein the tool is suspended from a wireline.

12. The method of claim 1 wherein said plurality of receiver coils comprises at least three receiver coils arranged in a receiver array.

Assignees

• Schlumberger Technology Corp
• Saudi Aramco Oil Company
• Saudi Arabian Oil Co

Inventors

• Zhang Ping
• Abdallah Wael
• Ma Shouxiang

Classifications

• G01V3/10 Primary

  using induction coils · CPC title

• G01N33/24 Primary

  Earth materials (G01N33/42 takes precedence) · CPC title

• G01V3/28

  using induction coils · CPC title

• Y02A90/30

  Assessment of water resources · CPC title