Method to characterize underground formation

• US 8,805,616 B2
• Filed: 12/21/2010
• Issued: 08/12/2014
• Est. Priority Date: 12/21/2010
• Status: Expired due to Fees

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Hinkel, Jerald J., Willberg, Dean, Pagels, Markus
• Primary Examiner(s): Nghiem, Michael
• Assistant Examiner(s): ALKAFAWI, EMAN A
• Application Number:
  US12/974,229
• Publication Number:
  US 20120152548A1
• Time in Patent Office: 1,330 Days
• Field of Search: 702/11, 702/12, 702/45, 702/47, 702/50, 702/151, 702/153, 73 38- 41
• US Class Current: 702/11
• CPC Class Codes: C09K 8/58 Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
• CPC Class Codes: E21B 43/16 Enhanced recovery methods for obtaining hydrocarbons
• CPC Class Codes: E21B 49/088 combined with sampling
• CPC Class Codes: G01N 24/081 Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity
• CPC Class Codes: G01N 33/24 Earth materials G01N33/42 takes precedence

Abstract

A method for determining a characteristic of an underground formation with a fluid is described. The method includes providing a sample material of the underground formation; measuring the permeability and the porosity of the sample material; performing a drainage test on the sample material using the fluid; estimating the threshold pressure of the sample material from the drainage test, the permeability and the porosity measurements; and determining the receding contact angle of the fluid on the sample material from the threshold pressure. The sample material can be disaggregated material.

Claims

1. A method for determining a characteristic of an underground formation with a fluid comprising:

measuring a permeability of a sample material of the underground formation;

measuring a porosity of the sample material;

performing a drainage test on the sample material using the fluid;

estimating, via a processor, a geometric mean capillary pressure of the sample material from the drainage test; and

determining, via the processor, a receding contact angle of the fluid on the sample material from the estimated geometric mean capillary pressure, the measured permeability, and the measured porosity;

wherein estimating the geometric mean capillary pressure comprises;

determining a threshold pressure representing a pressure threshold for directing a non-wetting fluid into a largest radii capillary of the sample material;

determining an irreducible saturation pressure representing a pressure for directing the non-wetting fluid into a smallest radii capillary of the sample material; and

calculating the geometric mean capillary pressure based on the threshold pressure and the irreducible saturation pressure.

2. The method of claim 1, further comprising disaggregating the sample material to form disaggregated sample material, wherein performing the drainage test comprises testing the disaggregated sample material.

3. The method of claim 2, wherein the disaggregation includes a grinding process.

4. The method of claim 2, wherein the disaggregated sample material is sieved to a specific size range.

5. The method of claim 1, wherein the sample material is a rock core from the underground formation.

6. The method of claim 1, further comprising performing an imbibition test on the sample material prior to the drainage test.

7. The method of claim 6, wherein the imbibition test includes an estimation of an advancing contact angle on the sample material.

8. The method of according to claim 1, wherein clay-swelling or other ancillary rock-fluid reactions of the sample material are controlled while performing the drainage test.

9. The method of according to claim 1, wherein the underground formation is a low-permeability formation with a reservoir matrix permeability of less than 0.1 mD.

10. The method of claim 1, wherein the underground formation is a low-permeability formation having a reservoir matrix permeability of less than 1 micro Darcy.

11. The method of claim 1 wherein the underground formation is a low-permeability formation penetrated by a wellbore.

12. The method of claim 1, wherein the wettability of the sample material is deduced from the receding contact angle of the fluid on the sample material.

13. The method of claim 1, wherein measuring the permeability comprising directing an inert gas through the sample material at different pressures.

14. The method of claim 1, wherein measuring the porosity comprises determining a bulk volume and an absolute volume of the sample material.

15. The method of claim 1, wherein measuring the porosity comprises determining a grain density of the sample material.

16. The method of claim 1, comprising performing an imbibition test to saturate the sample material, wherein performing the drainage test comprises spinning the saturated sample material in a centrifuge.

17. The method of claim 1, wherein performing the drainage test comprises spinning the sample material in centrifuge at a plurality of rotational speeds and determining a saturation for each of the plurality of rotational speeds.

18. The method of claim 1, wherein performing the drainage test comprises determining a saturation value for each of a plurality of capillary pressures.

19. The method of claim 1, wherein determining the threshold pressure comprises determining an inflection point of a function fit to the plurality of capillary pressures and corresponding saturation values.

20. The method of claim 1, wherein determining an irreducible saturation pressure comprises measuring an irreducible saturation of sample material and identifying a corresponding pressure as the irreducible saturation pressure.

21. The method of claim 1, wherein the geometric mean capillary pressure comprises a square root of a value representing a largest threshold pressure multiplied by a smallest threshold pressure for directing a non-wetting fluid into the sample material.

22. The method of claim 1, wherein the receding contact angle is determined based on a surface tension of the fluid.

23. The method of claim 1, wherein the receding contact angle is calculated using a following equation:

24. The method of claim 1, comprising treating the underground formation with the fluid.