Methods and Apparatus for Characterization of Petroleum Fluids Contaminated with Drilling Mud

• US 20110088949A1
• Filed: 05/06/2009
• Published: 04/21/2011
• Est. Priority Date: 05/13/2008
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Zhang, Dingan (Dan), Zuo, Youxiang (Jullan), Chengli, Dong, Mullins, Oliver C., O'Keefe, Michael
• Granted Patent: US 8,805,617 B2
• Time in Patent Office: Days
• US Class Current: 175/48
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells
• CPC Class Codes: E21B 49/10 using side-wall fluid samplers or testers

Abstract

A method and system for characterizing formation fluids contaminated with drilling mud that compensates for the presence of such drilling mud. The operations that characterize formation fluids contaminated with drilling mud can be carried out in real-time. The operations also characterize a wide array of fluid properties of petroleum samples contaminated with drilling mud in a manner that compensates for the presence of drilling mud. The operations characterize the viscosity and density of petroleum samples contaminated with drilling mud at formation conditions in a manner that compensates for differences between formation conditions and flowline measurement conditions. The operations also derive live fluid density unaffected by contamination of mud filtrate based on a scaling coefficient dependent on measured gas-oil ratio of the formation fluid. This scale factor accounts for excess volume created during mixing processes, which increases the accuracy of characterizations for high gas-oil ratio samples, especially gas condensate.

Claims

1. A method for characterizing formation fluid in an earth formation surrounding a borehole drilled into the earth formation, the method comprising:

a) sampling formation fluid at a given location within the borehole by drawing formation fluid into a flowline disposed within the borehole;

b) analyzing the formation fluid in the flowline to derive first data characterizing properties of the formation fluid in the flowline, the first data including data representing temperature and pressure of the formation fluid in the flowline;

c) deriving second data characterizing a plurality of properties of the formation fluid at the temperature and pressure of the formation fluid in the flowline, the second data based on the first data, and the second data characterizing properties of the formation fluid affected by contamination of mud filtrate in the formation fluid; and

d) deriving third data characterizing the plurality of properties of the formation fluid at the temperature and pressure of the formation fluid in the flowline, the third data based on the second data, and the third data characterizing properties of the formation fluid unaffected by contamination of mud filtrate in the formation fluid;

wherein the first data, second data, and third data are derived without sampling and analysis of formation fluid in the flowline at another location within the borehole.

2. A method according to claim 1, wherein the first data, second data, and third data are derived in real-time for real-time analysis of the formation fluid at the given location within the borehole in conjunction with the sampling of the formation fluid at the given location within the borehole.

3. A method according to claim 1, further comprising storing the third data for subsequent analysis and output.

4. A method according to claim 1, wherein the plurality of properties represented by the second and third data are selected from the group including hydrocarbon component weight fractions, live fluid density, live fluid viscosity, gas-oil ratio, API gravity, and an oil formation volume factor.

5. A method according to claim 1, further comprising deriving measurements of temperature and pressure of the formation fluid in the earth formation.

6. A method according to claim 5, wherein the temperature of the formation fluid in the earth formation is equated to the temperature of the formation fluid in the flowline as derived in b).

7. A method according to claim 5, further comprising:

e) deriving fourth data characterizing at least one property of the formation fluid at the temperature and pressure of the formation fluid in the earth formation, the fourth data based on corresponding third data, and the fourth data characterizing at least one property of the formation fluid unaffected by contamination of mud filtrate in the formation fluid.

8. A method according to claim 7, wherein the at least one property characterized by the fourth data is selected from the group including live fluid density and live fluid viscosity.

9. A method according to claim 8, wherein the fourth data is derived by EOS calculations that translate live fluid density at the temperature and pressure of formation fluid in the flowline to live fluid density at the temperature and pressure of the formation fluid in the earth formation.

10. A method according to claim 4, wherein the third data includes fluid density data that characterizes live fluid density of the formation fluid unaffected by contamination of mud filtrate in the formation fluid, the fluid density data derived from a model characterizing fluid density of a number of drilling muds as a function of temperature and pressure, wherein the module is used to estimate fluid density of drilling mud at the temperature and pressure of the formation fluid in the flowline.

11. A method according to claim 10, wherein the fluid density data is further derived from at least one parameter selected from the group including:

i) weight fraction of drilling mud as part of the formation fluid in the flowline,

ii) density of the formation fluid in the flowline unaffected by water contamination in the formation fluid, and

iii) a scaling factor based on the gas-oil ratio of the formation fluid in the flowline.

12. A method according to claim 11, wherein the weight fraction of drilling mud as part of the formation fluid in the flowline is calculated according to

13. A method according to claim 12, wherein the density of the formation fluid in the flowline unaffected by water contamination in the formation fluid is calculated according to

14. A method according to claim 13, wherein the density of water at the temperature and pressure of the formation fluid in the flowline (ρ

_w) is derived from a model characterizing fluid density of water as a function of temperature and pressure.

15. A method according to claim 4, wherein the third data includes fluid viscosity data that characterizes live fluid viscosity of the formation fluid unaffected by contamination of mud filtrate in the formation fluid, the fluid viscosity data derived from a model characterizing fluid viscosity of a number of drilling muds as a function of temperature and pressure, wherein the module is used to estimate fluid viscosity of drilling mud at the temperature and pressure of the formation fluid in the flowline.

16. A method according to claim 15, wherein:

the first data includes weight fraction data for a plurality of hydrocarbon components of the formation fluid in the flowline; and

the third data is derived from a gas phase molecular weight and a density of contaminated stock tank oil at standard conditions that are both calculated by solving EOS flash calculations carried out over a plurality of hydrocarbon components whose weight fractions are estimated in accordance with the weight fraction data of the first data.

17. A method according to claim 16, wherein the third data includes a gas-oil ratio unaffected by contamination of mud filtrate in the formation fluid, wherein the gas-oil ratio is derived from the gas phase molecular weight and the density of contaminated stock tank oil at standard conditions.

18. A method according to claim 17, wherein the gas-oil ratio unaffected by contamination of mud filtrate in the formation fluid is calculated as

19. A method according to claim 16, wherein the third data includes an API gravity unaffected by contamination of mud filtrate in the formation fluid, wherein the API gravity is derived from the gas phase molecular weight and the fluid density of contaminated stock tank oil at standard conditions.

20. A method according to claim 19, wherein the API gravity unaffected by contamination of mud filtrate in the formation fluid is calculated as

21. A method according to claim 16, wherein the third data includes an oil formation volume factor unaffected by contamination of mud filtrate in the formation fluid, wherein the oil formation volume factor is derived from the gas phase molecular weight and the density of contaminated stock tank oil at standard conditions.

22. A method according to claim 21, wherein the oil formation volume factor unaffected by contamination of mud filtrate in the formation fluid is calculated as

23. A method according to claim 1, further comprising generating and storing statistics for fluid properties of the formation fluid for subsequent analysis and output, the statistics based on the third data characterizing formation fluid at different locations in the borehole.

24. A method according to claim 7, further comprising generating and storing statistics for fluid properties of the formation fluid for subsequent analysis and output, the statistics based on the fourth data characterizing formation fluid at different locations in the borehole.

25. A system for characterizing formation fluid in an earth formation surrounding a borehole drilled into the earth formation, the system comprising:

a borehole tool positionable at different locations in the borehole, the borehole tool including fluid sampling means for sampling formation fluid at a given location by drawing formation fluid into a flowline disposed therein, and a fluid analyzer for analyzing the formation fluid in the flowline to derive first data characterizing properties of the formation fluid in the flowline, the first data including data representing temperature and pressure of the formation fluid in the flowline;

a data processing system operably coupled to the fluid analyzer, the data processing system adapted to derive second data and third data characterizing a plurality of properties of the formation fluid at the temperature and pressure of the formation fluid in the flowline, wherein the second data is based on the first data and the second data characterizes properties of the formation fluid affected by contamination of mud filtrate in the formation fluid, and wherein the third data is based on the second data and the third data characterizes properties of the formation fluid unaffected by contamination of mud filtrate in the formation fluid; and

wherein the first data, second data, and third data are derived without sampling and analysis of formation fluid in the flowline at another location within the borehole.

26. A system according to claim 25, wherein the first data, second data, and third data are derived in real-time for real-time analysis of the formation fluid at the given location within the borehole in conjunction with the sampling of the formation fluid at the given location within the borehole.

27. A system according to claim 25, wherein the data processing system stores the third data for subsequent analysis and output.

28. A system according to claim 25, wherein the plurality of properties represented by the second and third data are selected from the group including hydrocarbon component weight fractions, live fluid density, live fluid viscosity, gas-oil ratio, API gravity, and an oil formation volume factor.

29. A system according to claim 25, further comprising means for deriving measurements of temperature and pressure of the formation fluid in the earth formation.

30. A system according to claim 25, wherein the data processing system is adapted to derive fourth data characterizing at least one property of the formation fluid at the temperature and pressure of the formation fluid in the earth formation, the fourth data based on corresponding third data, and the fourth data characterizing at least one property of the formation fluid unaffected by contamination of mud filtrate in the formation fluid.

31. A system according to claim 30, wherein the at least one property characterized by the fourth data is selected from the group including live fluid density and live fluid viscosity.

32. A system according to claim 25, wherein said data processing system includes at least a surface-located data processing apparatus.

33. An apparatus for use in a system for characterizing formation fluid in an earth formation surrounding a borehole drilled into the earth formation, the system including a borehole tool positionable at different locations in the borehole, the borehole tool including fluid sampling means for sampling formation fluid at a given location by drawing formation fluid into a flowline disposed therein, and a fluid analyzer for analyzing the formation fluid in the flowline to derive first data characterizing properties of the formation fluid in the flowline, the first data including data representing temperature and pressure of the formation fluid in the flowline, the apparatus comprising a data processing system operably coupled to the fluid analyzer, the data processing system adapted to derive second data and third data characterizing a plurality of properties of the formation fluid at the temperature and pressure of the formation fluid in the flowline, wherein the second data is based on the first data and the second data characterizes properties of the formation fluid affected by contamination of mud filtrate in the formation fluid, wherein the third data is based on the second data and the third data characterizes properties of the formation fluid unaffected by contamination of mud filtrate in the formation fluid, and wherein the second data, and third data are derived without sampling and analysis of formation fluid at another location within the borehole.

34. An apparatus according to claim 33, wherein the second data and third data are derived in real-time for real-time analysis of the formation fluid at the given location within the borehole in conjunction with the sampling of the formation fluid at the given location within the borehole.

35. An apparatus according to claim 33, wherein the data processing system stores the third data for subsequent analysis and output.

36. An apparatus according to claim 33, wherein the plurality of properties represented by the second and third data are selected from the group including hydrocarbon component weight fractions, live fluid density, live fluid viscosity, gas-oil ratio, API gravity, and an oil formation volume factor.

37. An apparatus according to claim 33, further comprising means for deriving measurement of temperature and pressure of the formation fluid in the earth formation.

38. An apparatus according to claim 33, wherein the data processing system is adapted to derive fourth data characterizing at least one property of the formation fluid at the temperature and pressure of the formation fluid in the earth formation, the fourth data based on corresponding third data, and the fourth data characterizing at least one property of the formation fluid unaffected by contamination of mud filtrate in the formation fluid.

39. An apparatus according to claim 38, wherein the at least one property characterized by the fourth data is selected from the group including live fluid density and live fluid viscosity.