METHOD FOR CALIBRATING A HYDRAULIC MODEL

• US 20130049983A1
• Filed: 08/14/2012
• Published: 02/28/2013
• Est. Priority Date: 08/26/2011
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Rasmus, John, James, John, Bolchover, Paul
• Application Number:
  US13/585,791
• Publication Number:
  US 20130049983A1
• Time in Patent Office: Days
• US Class Current: 340/854.4
• CPC Class Codes: E21B 21/08 Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure valve arrangements therefor E21B21/10
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/10 Locating fluid leaks, intrusions or movements
• CPC Class Codes: E21B 49/005 Testing the nature of borehole walls or the formation by using drilling mud or cutting data
• CPC Class Codes: E21B 7/00 Special methods or apparatus for drilling
• CPC Class Codes: G01V 9/00 Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
• CPC Class Codes: G06F 15/00 Digital computers in general details G06F1/00 – G06F13/00; Data processing equipment in general

Abstract

A method for a hydraulic model for subterranean drilling fluids includes acquiring first and second axially spaced temperature and pressure measurements in the wellbore. The pressure measurements may be processed to obtain an interval density of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of interval densities corresponding to various wellbore intervals. The interval density(ies) may be processed in combination with the temperature and pressure measurements to compute one or more unknown coefficients of the hydraulic model.

Claims

1. A method for calibrating a hydraulic model comprising:

(a) deploying a tool string in a subterranean wellbore, the tool string including at least first and second longitudinally spaced sensor packages deployed at corresponding first and second measured depths in the wellbore, each of the sensor packages including a corresponding temperature sensor and a pressure sensor;

(b) acquiring first and second temperature measurements and first and second pressure measurements at the first and second measured depths;

(c) causing a processor to process the first and second pressure measurements to compute an interval density between the first and second measured depths in the wellbore; and

(d) causing the processor to process the interval density, the first and second pressure measurements, and the first and second temperature measurements to compute at least one coefficient of the hydraulic model.

2. The method according to claim 1, wherein the first and second temperature measurements and the first and second pressure measurements are acquired in (b) at a surface processor via a wired drill pipe communications channel and the interval density and at least one coefficient are computed at the surface in (c) and (d).

3. The method according to claim 1, wherein the temperature measurements and the pressure measurements are made in an internal region of the tool string.

4. The method according to claim 1, wherein drilling fluid is substantially static in the wellbore in (b).

5. The method according to claim 1, wherein:

the temperature measurements and the pressure measurements are made in an annular region external to the tool string;

the annular region is substantially free of cuttings; and

drilling fluid is substantially static in the wellbore.

6. The method of claim 1, further comprising:

(e) processing the hydraulic model to compute at least one of an internal fluid density and an annular fluid density at a third measured depth.

15. The method of claim 1, further comprising:

(e) processing the hydraulic model to compute at least one of an internal fluid density and an annular fluid density at another location in the wellbore.

7. A method for calibrating a hydraulic model comprising:

(a) deploying a tool string in a subterranean wellbore, the tool string including at least x axially spaced sensor packages, each of the sensor packages including a corresponding temperature sensor and a pressure sensor, x representing a number of unknown coefficients in the hydraulic model;

(b) acquiring temperature and pressure measurements at each of the at least x temperature and pressure sensors;

(c) causing a processor to processing the temperature and pressure measurements acquired in (b) to compute at least x interval densities; and

(d) causing the processor to process the interval densities computed in (c) and the temperature and pressure measurements acquired in (b) to compute values for the unknown coefficients in the hydraulic model.

8. The method of claim 7, wherein x is 6.

9. The method according to claim 7, wherein:

The temperature and pressure measurements are acquired at a surface processor via a wired drill pipe communications channel; and

the interval densities and the unknown coefficients are computed at the surface.

10. The method of claim 7, wherein the hydraulic model is represented by the following mathematical equation:

ρ

_mud=(i₁+j₁P+k₁P²)+(i₂+j₂P+k₂P²)T

wherein ρ

_mud represents a computed interval density, P represents an average pressure corresponding to the computed interval density, T represents an average temperature corresponding to the computed interval density, and i₁, j_i, k₁, i₂, j₂, and k₂, represent the unknown coefficients.

11. The method of claim 7, wherein the hydraulic model is represented by the following mathematical equation:

ρ

_mud=V_base[(a₁+b₁P+c₁P²)+(a₂+b₂P+c₂P²)T]+(1−

V_base)[(a₃+b₃P+c₃P²)+(a₄+b₄P+c₄P²)T]

wherein ρ

_mud represents a computed interval density, V_base represents a volume fraction of a base drilling fluid, P represents an average pressure corresponding to the computed interval density, T represents an average temperature corresponding to the computed interval density, a₁, b₁, c₁, a₂, b₂, and c₂ represent coefficients of the base drilling fluid, and a₃, b₃, c₃, a₄, b₄, and c₄ represent coefficients of a brine drilling fluid.

12. The method of claim 11, wherein:

x is 6;

a₁, b₁, c₁, a₂, b₂, and c₂ represent the unknown coefficients; and

a₃, b₃, c₃, a₄, b₄, and c₄ represent known coefficients of the brine drilling fluid.

13. The method according to claim 7, wherein the temperature and pressure measurements are made internal to the tool string when drilling fluid is substantially static in the wellbore.

14. The method according to claim 7, wherein:

the temperature and pressure measurements are made in an annular region external to the tool string;

the annular region is substantially free of cuttings; and

drilling fluid is substantially static in the wellbore.

16. A method for calibrating a hydraulic model comprising:

(a) acquiring temperature and pressure measurements made at a plurality of measured depths in a subterranean wellbore;

(b) processing the temperature and pressure measurements acquired in (a) to obtain a plurality of interval densities;

(c) repeating (a) and (b) at at least one other location in the subterranean wellbore; and

(d) processing the temperature measurements and the pressure measurements acquired in (a) and (c) and the interval densities obtained in (b) and (c) to compute values for unknown coefficients in the hydraulic model.

17. The method according to claim 16, wherein:

the temperature and pressure measurements are acquired at a surface processor via a wired drill pipe communications channel; and

the interval densities and the unknown coefficients are computed at the surface.

18. The method of claim 16, wherein the hydraulic model is represented by the following mathematical equation:

ρ

_mud=(i₁+j₁P+k₁P²)+(i₂+j₂P+k₂P²)T

wherein ρ

_mud represents a computed interval density, P represents an average pressure corresponding to the computed interval density, T represents an average temperature corresponding to the computed interval density, and i₁, j₁, k₁, i₂, j₂, and k₂, represent the unknown coefficients.

19. The method of claim 16, wherein the hydraulic model is represented by the following mathematical equation:

ρ

_mud=V_base[(a₁+b₁P+c₁P²)+(a₂+b₂P+c₂P²)T]+(1−

V_base)[(a₃+b₃P+c₃P²)+(a₄+b₄P+c₄P²)T]

wherein ρ

_mud represents a computed interval density, V_base represents a volume fraction of a base drilling fluid, P represents an average pressure corresponding to the computed interval density, T represents an average temperature corresponding to the computed interval density, a₁, b₁, c₁, a₂, b₂, and c₂ represent coefficients of the base drilling fluid, and a₃, b₃, c₃, a₄, b₄, and c₄ represent coefficients of a brine drilling fluid.

20. The method of claim 19, wherein:

a₁, b₁, c₁, a₂, b₂, and c₂ represent the unknown coefficients; and

a₃, b₃, c₃, a₄, b₄, and c₄ represent known coefficients of the brine drilling fluid.

21. The method according to claim 16, wherein the temperature and pressure measurements are made internal to the tool string when drilling fluid is substantially static in the wellbore.

22. The method according to claim 16, wherein:

the temperature and pressure measurements are made in an annular region external to the tool string;

the annular region is substantially free of cuttings; and

drilling fluid is substantially static in the wellbore.

23. The method of claim 16, further comprising:

(e) processing the hydraulic model to compute at least one of an internal fluid density and an annular fluid density at another location in the wellbore.