Method and system of fluid analysis and control in a hydrocarbon well

• US 6,490,916 B1
• Filed: 12/10/1999
• Issued: 12/10/2002
• Est. Priority Date: 06/15/1998
• Status: Expired due to Fees

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Kleinberg, Robert Leonard, Goodwin, Anthony Robert Holmes, Oddie, Gary Martin, Stephenson, Kenneth Edward, Griffin, Douglas D.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): WIGGINS, JOHN DAVID
• Application Number:
  US09/459,054
• Time in Patent Office: 1,096 Days
• Field of Search: 731/521--15, 73/190-- 1, 73/614-- 6, 73/645.2, 735/97, 735/99, 735/90, 166/250.01, 166/252.04, 166/309, 175/40-50
• US Class Current: 73/152.58
• CPC Class Codes: E21B 34/08 responsive to flow or pressure of the fluid obtained E21B34/10 takes precedence
• CPC Class Codes: E21B 43/12 Methods or apparatus for controlling the flow of the obtained fluid to or in wells E21B43/25 takes precedence; valve arrangements E21B34/00
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: E21B 49/081 with down-hole means for trapping a fluid sample E21B49/10 takes precedence
• CPC Class Codes: G01N 33/2823 Raw oil, drilling fluid or polyphasic mixtures

Abstract

A system and method of fluid analysis in a hydrocarbon borehole is disclosed. Acoustic energy is emitted into the production fluid downhole at a level which causes a phase transition in the fluid. The pressure associated with the phase transition is determined using the level of emitted acoustic energy. Advantageously, the determination of the phase transition pressure need not rely on mechanical means to substantially alter the volume of a sample of the fluid. An acoustic transducer can be installed either semi-permanently or permanently downhole in the well. The bubble point or the dew point can be detected. In the case of bubble point detection, the bubbles in the fluid can be detected by sensing variations in impedance of the acoustic transducer, and the level of emitted acoustic energy can determined by measuring the electrical energy used to drive the transducer.

A control system for a hydrocarbon well is also disclosed. A control valve system is used to control the flow of fluid being produced by the well. A real time sensor is provided downhole and is used to make real time measurements of phase characteristics of the fluid. A controller is used to control the valve system so as to reduce the risk of undesirable phase transitions in the fluid based on the real time measurements made by the sensor. The sensor includes an acoustic transducer configured to emit acoustic energy into the fluid at a level which causes a phase transition in the fluid. The controller determines the level of acoustic energy emitted into the fluid, and also determines the pressure associated with a phase transition using the level of emitted acoustic energy.

Claims

1. A method of fluid analysis in a hydrocarbon borehole for determining phase characteristics of a formation fluid comprising the steps of:

emitting acoustic energy into the fluid downhole using a transducer capable of generating at least one type of phase transition in the fluid, the acoustic energy being emitted at a level in which the acoustic energy causes an initiation of a phase transition in the fluid; and

determining whether a phase transition has occurred at least in part by measuring electrical impedance associated with the transducer.

2. The method of claim 1 wherein the step of determining whether a phase transition has occurred comprises determining the pressure associated with the phase transition and does not rely on mechanical means to substantially alter the volume of a sample of the fluid.

3. The method of claim 1 wherein the acoustic energy is emitted by an acoustic transducer that is installed at least semi-permanently downhole in the well.

4. The method of claim 3 wherein the acoustic energy is emitted by an acoustic transducer that is installed permanently downhole in the well.

5. The method of claim 3 wherein the acoustic transducer is contained in a flow-by tool that does not require that a sample be captured in a closed volume.

6. The method of claim 2 wherein the phase transition is the bubble point and the pressure associated with the phase transition is the bubble point pressure.

7. The method of claim 2 wherein the phase transition is the dew point and the pressure associated with the phase transition is the dew point pressure.

8. The method of claim 1 wherein the acoustic energy is emitted by the acoustic transducer at a frequency below 1 MHz.

9. The method of claim 8 wherein the acoustic energy is emitted by the acoustic transducer at a frequency between about 1 and about 50 kHz.

10. The method of claim 9 wherein the acoustic energy is emitted by the acoustic transducer at a frequency of approximately 40 kHz.

11. The method of claim 8 wherein the step of determining the pressure associated with the phase transition comprises detecting bubbles in said fluid using an acoustic transducer.

12. The method of claim 11 wherein the step of detecting bubbles in said fluid comprises detecting variations in impedance of the acoustic transducer.

13. The method of claim 12 wherein the same transducer is used to emit the acoustic energy and detect the bubbles.

14. The method of claim 13 wherein the level of emitted acoustic energy is determined by measuring the electrical energy used to drive the transducer.

15. A system for determining phase characteristics of a formation fluid in a hydrocarbon borehole comprising:

an acoustic transducer capable of generating at least one type of phase transition in the fluid, where the acoustic transducer is l;

ocated downhole configured to emit acoustic energy into the fluid at a level which causes a phase transition in the fluid; and

a controller in communication with said acoustic transducer adapted and configured to receive electrical signals representing electrical impedance associated with the acoustic transducer, and the controller adapted and configured to determine whether a phase transition has occurred at least in part by recognizing a characteristic change in the signals representing electrical impedance associated with the acoustic transducer.

16. The system of claim 15 wherein the determination whether a phase transition has occurred does not rely on mechanical means to substantially alter the volume of a sample of the fluid.

17. The system of claim 16 wherein the acoustic transducer is installed permanently downhole in the well.

18. The system of claim 16 wherein the acoustic transducer is contained in a flow-by tool that does not require that a sample be captured in a closed volume.

19. The system of claim 16 wherein the phase transition is the bubble point and the pressure associated with the phase transition is the bubble point pressure.

20. The system of claim 16 wherein the phase transition is the dew point and the pressure associated with the phase transition is the dew point pressure.

21. The system of claim 19 wherein the acoustic energy is emitted by the acoustic transducer at a frequency between about 1 and about 50 kHz.

22. The system of claim 21 wherein the pressure associated with the phase transition is determined by sensing variations in impedance of the acoustic transducer which indicate the presence of bubbles in said fluid.

23. A system for determining phase characteristics in a hydrocarbon fluid sample comprising:

a bottle enclosing a volume in which the fluid can be placed;

an acoustic transducer capable of generating at least one type of phase trasition in the fluid, where the acoustic transducer is positioned and configured to emit acoustic energy into the fluid at a level which causes a phase transition in the fluid; and

a controller in communication with said acoustic transducer adapter and configured to receive electrical signals representing electrical impedance associated with the acoustic transducer, and the controller adapted and configured to determine whether a phase transition has occurred at least in part by recognizing a characteristic change in the signals representing electrical impedance associated with the acoustic transducer.

24. The system of claim 23 wherein the phase transition is the bubble point and the controller is further adapted and configured to determine the pressure associated with the bubble point pressure.

25. The system of claim 23 wherein the phase transition is the dew point and the controller is further adapted and configured to determine the pressure associated with the dew point pressure.

26. The system of claim 24 wherein the acoustic energy is emitted by the acoustic transducer at a frequency less than about 1 MHz.

27. The system of claim 24 wherein the acoustic energy is emitted by the acoustic transducer at a frequency between about 1 and about 50 kHz.

28. The system of claim 26 wherein the pressure associated with the bubble point pressure is determined by sensing variations in impedance of the acoustic transducer which indicate the presence of bubbles in said fluid.

29. The system of claim 23 wherein the bottle comprises:

a movable piston disposed within the bottle and adapted control the pressure of the fluid sample; and

an inlet for allowing the fluid sample to enter and exit the bottle.

30. The system of claim 29 wherein the piston is adapted to separate the bottle into a region containing the fluid sample and a region containing a hydraulic fluid, the hydraulic fluid exerting pressure on the piston in order to control the pressure of the fluid sample.