Methods for obtaining a wellbore schematic and using same for wellbore servicing

• US 7,857,046 B2
• Filed: 05/31/2006
• Issued: 12/28/2010
• Est. Priority Date: 05/31/2006
• Status: Expired due to Fees

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Lovell, John R., Kane, Moussa
• Primary Examiner(s): Thompson; Kenneth
• Assistant Examiner(s): Hutchins; Cathleen R
• Application Number:
  US11/421,349
• Publication Number:
  US 20070277975A1
• Time in Patent Office: 1,672 Days
• Field of Search: 166/250.01, 166/64, 731/523.1, 731/522.7, 731/525.1, 731/525.5, 703/10
• US Class Current: 166/250.01
• CPC Class Codes: E21B 47/04 Measuring depth or liquid level

Abstract

Methods are described for determining or estimating a wellbore schematic, one embodiment comprising running one or more measured distances of coiled tubing into a wellbore while pumping a fluid at varying flow rates through the coiled tubing, and calculating true vertical depth of the wellbore using pressure and flow rate data of the fluid. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It may not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Claims

1. A method comprising:

(a) providing a coil of coiled tubing having a length able to reach a determined section of a wellbore;

(b) running one or more measured distances of the coiled tubing into the wellbore while pumping a fluid at varying flow rates down a wellhead and into the wellbore through the coiled tubing;

(c) measuring circulating pressure and pressure at bottom of the wellbore at various times during running and pumping;

(d) calculating wellbore parameters at the one or more measured distances using the pressure and flow rate data, wherein the wellbore parameters include true vertical depth of the wellbore at the one or more measured distances; and

(e) cross-plotting the true vertical depth versus the measured distances as a function of time.

2. The method of claim 1 comprising pumping a sequence of fluids through the coiled tubing at known circulating pressures and flow rates, sending bottom-hole data to the surface, and fitting the data to estimate a wellbore schematic assuming a minimal radius of curvature for the wellbore.

3. The method of claim 1 comprising transmitting real-time wellbore pressure data to the surface using one or more methods selected from wireless methods, wire methods via a data-carrying wire, fiber-optic lines, and combinations thereof.

4. The method of claim 3 comprising supplying the coiled tubing to a well site spooled onto a reel, selected from a communication line already inserted into the spool, and inserting a communication line into the coiled tubing at the well site.

5. The method of claim 1 comprising modeling friction pressure in the coiled tubing as two components:

friction pressure=A₁*(flow rate)ⁿ¹+A₂^*(flow rate)²ⁿ

where the first term to the right of the equal sign represents the pressure drop along that part of the coil spooled onto a reel, the second term to the right to the equal sign represents the pressure drop along the unspooled coil, and A₁ and A₂ are a function of viscosity of the fluid, local friction effects and internal diameter of the coiled tubing, and wherein n is an exponent between 1 and 2.

6. The method of claim 1 comprising measuring bottom-hole pressure without a downhole electronics package.

7. The method of claim 1 comprising repeating steps (b), (c), and (d) during repeated passes of the tubing through the wellbore.

8. The method of claim 1 wherein the running one or more measured distances of the coiled tubing into the wellbore comprises running into wellbores selected from the group consisting of substantially vertical wellbores, deviated wellbores, and combinations thereof.

9. The method of claim 1 wherein cross-plotting comprises cross-plotting the true vertical depth versus the measured distances as a function of time to create a wellbore schematic while flowing fluids into the wellbore.

10. A method, comprising

(a) providing a coil of coiled tubing having a length able to reach a determined section of a wellbore;

(b) running one or more measured distances of the coiled tubing into the wellbore while pumping a fluid at varying flow rates through the coiled tubing;

(c) measuring circulating pressure and pressure at bottom of the wellbore at various times during running and pumping;

(d) calculating wellbore parameters at the one or more measured distances using the pressure and flow rate data, wherein the wellbore parameters include true vertical depth of the wellbore at the one or more measured distances; and

(e) modeling circulation pressure wherein a total of LT feet of coiled tubing is brought to the wellhead and MD(t) has been run into the wellbore at time t, and the friction pressure is modeled as;

friction pressure=a₁*(LT−

MD(t)) *(flow rate(t))ⁿ¹⁺a₂*MD(t)*(flow rate(t))ⁿ²

where coefficients a₁ and a₂ are a function of viscosity of the fluid, local friction effects and internal diameter of the coiled tubing, and wherein n is an exponent between 1 and 2 and wherein a₁ and a₂, and exponents n1 and n2 are estimated by varying the flow rate and measured distance.

11. The method of claim 10 comprising assuming the fluid density remains constant so that hydrostatic pressure=TVD(t)*density*g.

12. The method of claim 10 comprising assuming the fluid density is changing with wellbore depth into a vertical wellbore, measuring a difference between fluid pressure just outside a terminus of the coiled tubing (P_an) and pressure at an annulus exit at the wellhead (WHP), and calculating fluid density using the equation:

13. The method of claim 10 comprising assuming the fluid density is changing with wellbore depth in a wellbore having a vertical portion and a deviated portion, measuring a difference between fluid pressure just outside a terminus of the coiled tubing (P_an) and pressure at an annulus exit at the wellhead (WHP), and calculating fluid density using the equation:

14. The method of claim 10 wherein the MD is varied during the time the coiled tubing is running in.

15. The method of claim 10 further comprising performing at least one wellbore servicing operation.

16. A method comprising:

(a) running one or more measured distances of coiled tubing into a wellbore while pumping a fluid at varying flow rates down a wellhead and into the wellbore through the coiled tubing;

(b) calculating true vertical depth of the wellbore using pressure and flow rate data of the fluid; and

(c) cross-plotting the true vertical depth versus the measured distances as a function of time.