System and method for predicting compatibility of fluids with metals

• US 20080126383A1
• Filed: 09/11/2006
• Published: 05/29/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Tetra Technologies Incorporated
• Original Assignee: Tetra Technologies Incorporated
• Inventors: CARTER, THOMAS S, MISHRA, SURENDRA K, McKennis, Jeffrey, Perrin, Glenn
• Granted Patent: US 7,519,481 B2
• Time in Patent Office: Days
• US Class Current: 707/102
• CPC Class Codes: E21B 41/02 in situ inhibition of corrosion in boreholes or wells

Abstract

A method and system for selecting fluids for compatibility with specified metals exposed to oil field environments. Metal specimens are tested for corrosion and/or cracking behavior by exposing them to fluids under stressful test conditions. The testing is conducted under variable temperature, pressure, pH, fluid density, metallurgical stress, additives, cover gases and combinations thereof. The results from the stress testing are stored in a database. The test results are evaluated using encoded logic embedded in software media. Fluid compatibility evaluation software, developed from the stress test results, is executed to determine the cracking susceptibility of metals exposed to fluids under stressful conditions. A cracking susceptibility index can be developed to provide a quantitative indicator of cracking susceptibility. Fluid recommendation reports utilize the cracking susceptibility index values to rank compatible fluids. The reports also list optional additives to be used with the fluids.

Claims

1. A system for selecting fluids for compatibility with metals exposed to oil field environments, the system comprising:

a database, the database comprising test results obtained from stress testing one or more metals and one or more fluids under down hole conditions;

one or more media comprising encoded logic for evaluating the stress test results;

one or more means for executing the logic wherein the executed logic selects the one or more fluids compatible for use with the one or more metals as indicated by the test results for the metal'"'"'s susceptibility towards cracking of the one or more metals and within the one or more fluids.

2. The system of claim 1 wherein the stress testing comprises a modification of a NACE C-ring test protocol.

3. The system of claim 1 wherein the stress testing comprises bent beam testing, slow strain rate testing, U-bend, electrochemical testing, acoustical testing and testing with loading bolts and strain gauges.

7. The system of claim 1 wherein the one or more metals further comprise mill scales and intact markings.

16. The system of claim 1 wherein the database comprises pre-cracking corrosion data and cracking data.

17. The system of claim 16 wherein the pre-cracking corrosion data comprises localized corrosion, severe localized corrosion and pitting.

18. The system of claim 1 further comprising a cracking susceptibility index, wherein cracking susceptibility is determined by ranking the fluids within the index.

19. The system of claim 18 wherein the cracking susceptibility index comprises a range of numerical values between 0 and 100.

20. The system of claim 19 wherein a numerical value greater than 25 is indicative of a greater susceptibility towards corrosion and cracking.

21. The system of claim 18 wherein the cracking susceptibility index comprises a range of alphabetical values.

4-6. -6. (canceled)

8. The system of claim I further comprising a test protocol, the test protocol comprising test procedures for testing variations in well operating parameters and formation properties.

9. The system of claim 8 wherein the well operating parameters and formation properties comprise variations in temperature, pressure, pH, metallurgical stress, fluid density, cover gases and combinations thereof.

10-15. -15. (canceled)

22-24. -24. (canceled)

25. A system for selecting fluids for compatibility with metals exposed to down hole conditions, the system comprising:

an apparatus for stress testing one or more metals and one or more fluids under down hole conditions;

a database, the database comprising test results obtained from stress testing;

one or more media comprising encoded logic for evaluating the stress test results;

one or more means for executing the logic wherein the executed logic generates a cracking susceptibility index, the cracking susceptibility index used to select one or more fluids compatible with the one or metals under down hole conditions.

30. The system of claim 25 wherein the one or more metals comprise highly stressed C-rings, the highly stressed C-rings comprising elastic deformation and plastic deformation.

33. The system of claim 25 further comprising one or more real-time stress test monitors.

37. The system of claim 25 wherein the test conditions comprise contaminants, the contaminants comprising natural contaminants, air, hydrogen sulphide and/or carbon dioxide.

39. The system of claim 25 wherein the cracking susceptibility index comprises a range of values representing a quantitative relative susceptibility towards cracking.

40. The system of claim 39 wherein the cracking susceptibility index comprises an arbitrary cracking susceptibility index value for predicting one or more compatible fluids, the arbitrary cracking susceptibility value comprising a number between 0 and 100.

41. The system of claim 40 wherein fluids comprising cracking susceptibility values below the arbitrary value are indicative of compatible and/or passing fluids.

42. The system of claim 40 wherein fluids comprising cracking susceptibility values above the arbitrary value are indicative of incompatible and/or failing fluids.

44. The system of claim 25 further comprising one or more fluid recommendation reports, the one or more fluid recommendation reports comprising a ranking of the fluids based on the cracking susceptibility index.

26-29. -29. (canceled)

31-32. -32. (canceled)

34-36. -36. (canceled)

38. (canceled)

43. (canceled)

45-54. -54. (canceled)

55. A method for selecting fluids for compatibility with metals exposed to oil field environments, the method comprising:

(a) stress testing a combination of one or more metals and one or more fluids under downhole conditions;

(b) storing the test results from the stress testing in a database;

(c) developing one or more software programs for evaluating the stress test results; and

(d) executing the one or more software programs to predict the one or more fluids that are compatible for use with the one or more metals under downhole conditions by creating a cracking susceptibility index, the cracking susceptibility index used to select fluids that minimize susceptibility towards cracking of the one or more metals.

67. The method of claim 55 further comprising a computer comprising one or more processors and a computer memory.

68. The method of claim 55 wherein the one or more software programs for evaluating the stress test results are stored in the computer memory.

56-66. -66. (canceled)

69-75. -75. (canceled)

76. A method for selecting fluids for compatibility with metals exposed to oil field environments, the method comprising:

(a) stress testing one or more metals and one or more fluids under downhole conditions;

(b) storing the test results in a database;

(c) evaluating the test results using logic encoded in one or more media; and

(d) executing the logic to generate a cracking resistance index, the cracking resistance index used to select one or more of the metals having resistance to cracking when exposed to the one or more fluids.

77-95. -95. (canceled)