Drilling system with downhole apparatus for determining parameters of interest and for adjusting drilling direction in response thereto

• US 5,812,068 A
• Filed: 12/12/1995
• Issued: 09/22/1998
• Est. Priority Date: 12/12/1994
• Status: Expired due to Term

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Deady, Ronald, Wisler, MacMillan M., Meyer, Wallace H., Leggett, James V. III, Beimgraben, Herbert W., Minette, Daniel, Hubner, Bernard G.
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US08/570,838
• Time in Patent Office: 1,015 Days
• Field of Search: 340/855.5, 340/853.1, 340/855.6, 340/856.3, 73/152.02, 73/152.03, 73/152.05, 73/152.28, 73/152.46, 175/40, 175/45
• US Class Current: 340/855.5
• CPC Class Codes: E21B 44/005 Below-ground automatic control systems
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: E21B 47/26 Storing data down-hole, e.g. in a memory or on a record carrier
• CPC Class Codes: E21B 7/068 drilled by a down-hole drilling motor down-hole drives per se E21B4/00, E21B7/067 takes precedence
• CPC Class Codes: G01V 11/00 Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00

Abstract

The present invention provides a measurement-while-drilling (MWD) system having a downhole computer and multiple downhole sensors. Relatively large amounts of basic or "raw" data are measured by downhole sensors, and these data are processed within a downhole computer to be reduced to parameters of interest, which may be utilized to control the drilling operation by downhole devices, stored downhole, telemetered to the surface, or both. The measurements may be correlated downhole with stored reference data thereby providing additional information pertaining to the drilling operation. Downhole depth correlation between downhole measured parameters may be made by utilizing surface determined or downhole determined borehole depth.

Claims

1. A measurement-while-drilling downhole apparatus for use in drilling a borehole in a formation, comprising:

(a) a plurality of sensors within the downhole assembly for providing a plurality of downhole measurements, said plurality of sensors including a device for providing measurements of the resistivity of the formation; and

(b) a computer within the downhole assembly for transforming the plurality of downhole measurements into one or more parameters of interest during drilling of the borehole in accordance with programmed instructions provided to the computer, one said parameter of interest being water saturation of the formation.

2. The apparatus as specified in claim 1, wherein the computer determines the water saturation as:

space="preserve" listing-type="equation">S.sub.w =c.sub.I (R.sub.w /R.sub.t).sup.0.5 φ

.sub.t

where R_t is resistivity of a deep formation zone measured by the resistivity device, R_w is a predetermined value of resistivity of water, φ

_t is the porosity of the formation and c_I is a constant.

3. The apparatus as specified in claim 1, wherein the computer determines the water saturation is that of a flushed zones (S_xo) along the borehole and is determined as:

space="preserve" listing-type="equation">S.sub.xo =(c.sub.2 /φ

.sub.t)(R.sub.mf /R.sub.xo).sup.0.5

where R_mf is resistivity of a mud filtrate that is stored in a memory associated with the computer, R_xo is resistivity of a shallow zone measured by the resistivity device, φ

_t is porosity of the formation and c₂ is a constant.

4. The apparatus as specified in claim 1, wherein the computer determines recovery factor index "RFI" as a parameter of interest as:

space="preserve" listing-type="equation">RFI=S.sub.xo -S.sub.w /(1-S.sub.w)

wherein, S_xo is water saturation of a flushed zone and S_w is the water saturation of the formation along the borehole.

5. An apparatus for use in drilling boreholes, comprising:

(a) a drill bit;

(b) a downhole assembly coupled to the drill bit, said downhole assembly including;

(i) a plurality of sensors of providing measurements for selected properties of the formation along the borehole,

(ii) a computer having programmed instruction associated therewith, said computer transforming a certain number of measurements into one or more parameters of interest, and

(iii) a deflection device for causing the drill bit to change drilling direction during drilling of the borehole based on one of the parameter of interest.

6. The apparatus as specified in claim 5, wherein the computer determines deviation of the downhole assembly from a predetermined borehole path as a parameter of interest.

7. The apparatus as specified in claim 6, wherein the predetermined borehole path is stored in a memory associated with the computer.

8. The apparatus as specified in claim 6, wherein the downhole assembly is adapted to receive signals from a remote device for altering the stored predetermined borehole path.

9. The apparatus as specified in claim 8, wherein the remote device is at the earth'"'"'s surface during the drilling of the boreholes.

10. The apparatus as specified in claim 6, wherein the computer causes the deflection device to reorient the drill bit when the deviation is greater than a predetermined value.

11. The apparatus as specified in claim 5, wherein the deflection device is an adjustable stabilizer.

12. The apparatus as specified in claim 11, wherein the adjustable stabilizer has a plurality of independently adjustable members.

13. The apparatus as specified in claim 5, wherein the deflection device contains two spaced adjustable stabilizers.

14. The apparatus as specified in claim 13, wherein each of the adjustable stabilizers has a plurality of independently adjustable members.

15. The apparatus as specified in claim 14, wherein the independently adjustable members are hydraulically operated to orient the drill bit in a desired direction.

16. The apparatus as specified in claim 14, wherein the independently adjustable members are electro-mechanically operated to orient the drill bit in a desired direction.

17. The apparatus as specified in claim 5, wherein the deflection device contains an adjustable bend placed between two stabilizers for defining a three-point geometry useful for orienting the drill string in a desired direction.

18. The apparatus as specified in claim 5, wherein the deflection device contains an adjustable subassembly coupled to the drill bit for causing the drill bit to orient in a desired direction independent of the drill string direction.

19. The apparatus as specified in claim 5, wherein the plurality of sensors determines the downhole measurements substantially simultaneously.

20. A downhole apparatus for use in drilling a borehole, comprising:

(a) a plurality of sensors for providing measurements of selected properties of the formation along the borehole;

(b) a computer having programmed instruction associated therewith, said computer transforming a certain number of measurements into one or more parameters of interest; and

(c) a position measuring device for determining the location of the downhole assembly in the borehole during the drilling of the borehole, said position determining device selected from a group of devices consisting of an inertial guidance device and a three-axis accelerometer.

21. The apparatus as specified in claim 20, wherein the computer determines the absolute position of the downhole assembly in the borehole from the measurements made by the position measuring device.

22. The apparatus as specified in claim 20, wherein the computer determines borehole profile during the drilling of the borehole.

23. The apparatus as specified in claim 22, wherein the computer determines differences between the determined borehole profile and a predetermined profile stored in a memory associated with the computer.

24. The apparatus as specified in claim 22, wherein the computer stores the determined borehole profile in a memory associated with the computer.

25. The apparatus as specified in claim 22, wherein the bottom hole assembly transmits the determined borehole profile to a surface equipment during the drilling of the borehole.

26. A measurement-while-drilling downhole apparatus for use in drilling a borehole into a subsurface formation, comprising:

(a) a plurality of sensors within the downhole assembly for providing a plurality of downhole measurements, said plurality of sensors including a device for providing measurements of the resistivity of the formation; and

(b) a computer within the downhole assembly for transforming the plurality of downhole measurements into one or more parameters of interest during drilling of the borehole in accordance with programmed instructions provided to the computer, wherein one said parameter of interest is a recovery factor index "RFI" of formations along the borehole.

27. The apparatus as specified in claim 26, wherein the computer determines recovery factor index "RFI" as a parameter of interest as:

space="preserve" listing-type="equation">RFI=S.sub.xo -S.sub.w /(1-S.sub.2)

wherein, S_xo is water saturation of a flushed zone and S_w is the water saturation of the formation along the borehole.

30. The apparatus as defined in claim 26, wherein the plurality of sensors further comprises density and porosity sensors and the computer determines the porosity (φ

_t) downhole as a function of the measurements from the density and porosity sensors.

31. The apparatus as specified in claim 30, wherein φ

_t is determined as;

φ

_t =(φ

_n +φ

_d)/2, for liquid filled formations and

φ

_t =((φ

_n² +φ

_d²)⁰.5, for gas-bearing formations,

where φ

_n is formation neutron porosity measured downhole during drilling by the porosity measuring device and φ

_d is formation porosity determined downhole during drilling from measurements obtained by the density device.

28. A measurement-while-drilling borehole apparatus for use in drilling a borehole into a subsurface formation, comprising:

(a) a plurality of sensors within the downhole assembly for providing selected downhole measurements, said plurality of sensors including a device for providing measurements of the resistivity of the formation; and

(b) a computer within the downhole assembly for transforming the plurality of downhole measurements into one or more parameters of interest during drilling of the borehole in accordance with programmed instructions provided to the computer, one said parameter of interest being an estimate of movable hydrocarbons from a selected formation along the borehole.

29. A measurement-while-drilling downhole apparatus for use in drilling a borehole into a subsurface formation, comprising:

(a) a plurality of sensors within the downhole assembly for providing a plurality of downhole measurements, said plurality of sensors including a device for providing measurements of the porosity of the formation and a density device for providing measurements relating to the density of the formation; and

(b) a computer within the downhole assembly for transforming the plurality of downhole measurements into on or more parameters of interest during drilling of the borehole in accordance with programmed instructions provided to the computer, one said parameter of interest being the porosity (φ

_t) of the formation.

32. A method of drilling a wellbore in a subterranean formation, comprising:

(a) providing a downhole apparatus having;

(i) a plurality of sensors for providing a plurality of downhole measurements, said plurality of sensors including a device for providing measurements of the resistivity of the formation; and

(ii) a computer within the downhole assembly for transforming the plurality of downhole measurements into one or more parameters of interest;

(b) making measurements during drilling of the borehole by the plurality of sensors; and

(c) determining downhole by the computer one or more parameters of interest from the plurality of measurements, said parameters of interest selected from a group consisting of water saturation, porosity, recovery factor index, and an estimate of movable hydrocarbons from a selected formations along the borehole.