Integrated permeability measurement and resistivity imaging tool

• US 5,335,542 A
• Filed: 02/12/1993
• Issued: 08/09/1994
• Est. Priority Date: 09/17/1991
• Status: Expired due to Term

• Current Assignee: Schlumberger-Doll Research Center (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Murphy, William, Kuchuk, Fikri, Rossi, David, Plumb, Richard, Dave, Yogesh, Goode, Peter, Helwig, James, Auzerais, Francois M., Ramakrishnan, T. S., Dussan, Elizabeth B. V
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): DOMBROSKE, GEORGE M
• Application Number:
  US08/016,933
• Time in Patent Office: 543 Days
• Field of Search: 73/152, 73/155, 73/153, 73/38, 166/250, 166/264, 175/48, 324/324, 324/325, 324/353
• US Class Current: 73/152.08
• CPC Class Codes: E21B 33/1246 inflated by down-hole pumping means operated by a pipe string
• CPC Class Codes: E21B 49/008 by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor measuring pressure E21B47/06
• CPC Class Codes: E21B 49/088 combined with sampling
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers
• CPC Class Codes: G01N 15/0826 and measuring fluid flow rate, i.e. permeation rate or pressure change

Abstract

A borehole tool having adjacently located fluid injection/withdrawal apparatus and an electromagnetic measurement apparatus is provided. The electromagnetic measurement apparatus can be an imaging apparatus for helping set the tool in desired locations for permeability testing via fluid injection or withdrawal. In a second mode, during fluid injection or withdrawal, and if desired, before and/or after injection or withdrawal, a plurality of electromagnetic measurements (images) are made. Based on the electromagnetic and hydraulic measurements, and a model which interrelates the measurements, determinations are made as to various characteristics of the formation, including effective permeabilities. Related methods for utilizing the tool and for treating the data in an integrated fashion are also set forth.

Claims

1. Apparatus for the investigation of an earth formation transverse by a borehole, comprising:

a) a plurality of electrode means for making electrical contact with a segment of a wall of said borehole and for making electrical measurements relating to an electromagnetic investigation of said earth formation adjacent said segment of said borehole wall;

b) hydraulic port means for making hydraulic contact with said formation;

c) flow means coupled to said hydraulic port for accomplishing at least one of injecting fluid into said formation and withdrawing fluid from said formation via said hydraulic port;

d) hydraulic property measurement means for determining pressures at said hydraulic port during withdrawal of fluid from said formation or during injection of fluid into said formation, wherein, said plurality of electrode means make said electrical measurements during said withdrawal of fluid from said formation or during said injection of fluid into said formation, and said hydraulic port means is sufficiently adjacent said plurality of electrode means such that said electrical measurements are impacted by said withdrawal of fluid or said injection of fluid.

2. Apparatus according to claim 1, wherein:

said plurality of electrode means and said hydraulic port means are located on a single probe means which laterally extends from said apparatus, wherein said plurality of electrode means comprises an actively focussed electrode means with concentric electrodes, and said hydraulic port means is located concentrically and central said concentric electrodes.

3. Apparatus according to claim 1, wherein:

said hydraulic port means comprises first and second inflatable straddle packers longitudinally displaced from each other along said apparatus, said inflatable straddle packers when inflated forming hydraulic seals azimuthally around said borehole and defining a hydraulic port in fluid communication with said formation.

4. Apparatus according to claim 1, further comprising:

e) processing means coupled to said hydraulic property measurement means and said plurality of electrode means for determining at least one hydraulic or electromagnetic characteristic of said formation.

5. Apparatus according to claim 4, wherein:

said processing means determines said at least one hydraulic or electromagnetic characteristic according to an equation

space="preserve" listing-type="equation">I=E[h(x,y),Y]

where I are current measurements comprising said measurements made by said electrode means, U are known voltages impressed by said electrode means onto said formation, y are known values for a second set of formation characteristics, x is said at least one hydraulic or electromagnetic unknown characteristic, h is a function which relates the input formation variables x and y and the spatial distribution of formation conductivity according to a fluid mechanical and petrophysical model, and E is a function which maps the spatial distribution of formation conductivity and the known voltages U to said measurements I.

6. Apparatus according to claim 5, wherein:

said processing means predicts current measurements I_pred based on said equation, compares said predicted measurements with said measurements, and minimizes differences between said predicted measurements and said measurements to determine a value for said at least one characteristic.

7. Apparatus according to claim 4, wherein:

said processing means determines said at least one hydraulic or electromagnetic characteristic according to an equation

space="preserve" listing-type="equation">U=F[h(x,y),I]

where U are measured voltages comprising said measurements made by said electrode means, I are known currents injected by said electrode means into said formation, y are known values for a second set of formation characteristics, x is said at least one unknown hydraulic or electromagnetic characteristic, h is a function which the relates the input formation variables x and y and the spatial distribution of formation conductivity according to a fluid mechanical and petrophysical model, and F is a function which maps the spatial distribution of formation conductivity and the known currents I to said measurements U.

8. Apparatus according to claim 7, wherein:

said processing means predicts measurements U_pred based on said equation, compares said predicted measurements with said measurements, and minimizes differences between said predicted measurements and said measurements to determine a value for said at least one unknown characteristic.

9. Apparatus according to claim 1, wherein:

said plurality of electrode means are located on a first laterally extending pad means, and

said hydraulic port means is located on a second laterally extending pad means substantially adjacent said first laterally extending pad means.

10. Apparatus according to claim 9, wherein:

a single probe means of said apparatus includes said first and second laterally extending pad means, said single probe means having means for urging said probe into contact with said formation.

11. Apparatus according to claim 10, further comprising:

spring bias means coupled to each first laterally extending pad means for limiting the setting force of said first laterally extending pad means when said probe is urged into contact with said formation by said means for urging.

12. Apparatus according to claim 10, wherein:

said apparatus includes first and second of said probe means, said first probe means being azimuthally displaced from said second probe means around said apparatus.

13. Apparatus according to claim 10, wherein:

said apparatus includes first and second of said probe means, said first probe means being longitudinally displaced from second probe means along said apparatus.

14. Apparatus according to claim 13, wherein:

said apparatus includes a third said probe means, said third probe means being azimuthally displaced from said first probe means.

15. A method for investigating an earth formation with a borehole tool having a plurality of electrode means for making electrical contact with a segment of a wall of said borehole and for making measurements relating to an electromagnetic investigation of said earth formation adjacent said segment of said borehole wall, a hydraulic port means substantially adjacent said plurality of electrode means for making hydraulic contact with said formation, a flow means coupled to said hydraulic port means for injecting fluid into said formation and/or for withdrawing fluid from said formation via said hydraulic port means, and hydraulic property measurement means for determining pressures at said hydraulic probe before, during, or after withdrawal or injection of fluid from said formation, said method comprising:

a) determining a depth at which said borehole tool is to be set;

b) lowering or raising said borehole tool to approximately said depth;

c) scanning said formation with said plurality of electrode means to provide first electromagnetic images of said formation at a plurality of different depths near said depth;

d) using said first electromagnetic images to determine exactly where to set said borehole tool;

e) setting said borehole tool with said hydraulic port means at exactly a determined location; and

f) with said flow means, withdrawing fluid from and/or injecting fluid into said formation via said hydraulic port means with said hydraulic port means set at exactly said determined location.

16. A method according to claim 15, wherein:

said step of determining a depth at which said borehole tool is to be set comprises obtaining second electromagnetic images of said formation, and locating depths of interest based on said second electromagnetic images.

17. A method according to claim 16, wherein:

said second electromagnetic images of said formation are obtained by said borehole tool.

18. A method according to claim 15, wherein:

said step of determining a relative depth at which said borehole tool is to be set comprises obtaining information regarding strata of said formation and their depths in said formation from a second borehole tool.

19. A method according to claim 15, wherein:

said step of using said first electromagnetic images further comprises comparing said second electromagnetic images with said first electromagnetic images.

20. A method according to claim 15, further comprising:

g) while withdrawing fluid from or injecting fluid into said formation via said hydraulic port means, scanning said formation with said plurality of electrode means to provide a plurality of electromagnetic images of said formation adjacent said hydraulic port means over time.

21. A method for investigating an earth formation with a borehole tool having a plurality of electrode means for making electrical contact with a segment of a wall of said borehole and for making measurements relating to an electromagnetic investigation of said earth formation adjacent said segment of said borehole wall, a hydraulic port means substantially adjacent said plurality of electrode means for making hydraulic contact with said formation, a flow means coupled to said hydraulic port means for injecting fluid into said formation and/or for withdrawing fluid from said formation via said hydraulic port means, and hydraulic property measurement means for determining at least pressures at said hydraulic probe before, during, or after withdrawal or injection of fluid from said formation, said method comprising:

a) setting said borehole tool at a depth in said formation;

b) with said flow means, withdrawing fluid from or injecting fluid into said formation via said hydraulic port means;

c) scanning said formation with said plurality of electrode means to provide electromagnetic information regarding said formation at said depth at two different times, a first of said two different times being either before or at a first time during said fluid injection or withdrawal, and a second of said two different times being either at a second time different from said first time during said fluid injection or withdrawal or after said fluid injection or withdrawal.

22. A method according to claim 21, wherein:

said step of scanning said formation comprises scanning said formation at a plurality of times during fluid injection into or withdrawal from said formation.

23. A method according to claim 21, further comprising:

upon withdrawing fluid from or injecting fluid into said formation, making measurements with said hydraulic property measurement means, and from said measurements of said hydraulic property measurement means and said electromagnetic information measured by said plurality of electrode means, determining a value for at least one characteristic of said formation. second set of formation characteristics, x is said at least one unknown hydraulic or electromagnetic characteristic, h is a function which the relates the input formation variables x and y and the spatial distribution of formation conductivity according to a fluid mechanical and petrophysical model, and F is a function which maps the spatial distribution of formation conductivity and the known currents I to said measurements U.

24. A method according to claim 23, wherein

from said electromagnetic information regarding said formation at said depth at said two different times, determining said at least one characteristic of said formation according to an equation

25. A method according to claim 23, wherein:

from said electromagnetic information regarding said formation at said depth at said two different times, determining said at least one characteristic of said formation according to an equation

space="preserve" listing-type="equation">U=F[h(x,y),I]

where U are voltage measurements and comprise said electromagnetic information provided by said electrode means, I are known currents injected by said electrode means into said formation, y are known values for a second set of formation characteristics, x is said at least one characteristic, h is a function which relates the input formation variables x and y and the spatial distribution of formation conductivity according to a fluid mechanical and petrophysical model, and F is a function which maps the spatial distribution of formation conductivity and the known currents I to said voltage measurements U.