NATURAL FRACTURE INJECTION TEST

• US 20140058686A1
• Filed: 08/22/2012
• Published: 02/27/2014
• Est. Priority Date: 08/22/2012
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes, a GE Company, LLC (Baker Hughes Company)
• Inventors: Moos, Daniel, Anderson, Christopher RL, Barton, Colleen A.
• Granted Patent: US 9,366,122 B2
• Time in Patent Office: Days
• US Class Current: 702/51
• CPC Class Codes: E21B 43/26 by forming crevices or fractures
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 49/008 by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor measuring pressure E21B47/06
• CPC Class Codes: E21B 49/08 Obtaining fluid samples or testing fluids, in boreholes or wells

Abstract

A method for estimating a property of an earth formation penetrated by a borehole includes: performing a borehole integrity test at a pressure less than a fracture gradient pressure of the formation to provide leakage data; injecting a fluid into the formation at a first pressure greater than the fracture gradient pressure during a first injection time interval using a fluid injector; measuring pressure versus time using a pressure sensor and a timer during a first test time interval to provide first pressure data; injecting a fluid into the formation at a second flow rate greater than the first flow rate during a second injection time interval using the fluid injector; measuring pressure versus time using the pressure sensor and the timer during a second test time interval to provide second pressure data; and estimating the property using the first pressure data, the second pressure data, and the leakage data.

Claims

1. A method for estimating a property of an earth formation penetrated by a borehole, the method comprising:

performing a borehole integrity test at a pressure less than a fracture gradient pressure of the formation, the borehole integrity test providing leakage data;

injecting a fluid into the formation at a first pressure greater than the fracture gradient pressure at a first flow rate during a first injection time interval using a fluid injector;

measuring pressure versus time using a pressure sensor and a timer during a first test time interval after the injecting for the first injection time interval to provide first pressure data;

injecting a fluid into the formation at a second flow rate greater than the first flow rate during a second injection time interval using the fluid injector;

measuring pressure versus time using the pressure sensor and the timer during a second test time interval after the injecting for the second injection time interval to provide second pressure data; and

estimating the property using the first pressure data, the second pressure data, and the leakage data.

2. The method according to claim 1, wherein the property is permeability or injectivity.

3. The method according to claim 1, further comprising estimating a hydraulic stimulation pressure to stimulate the formation using the first pressure data, the second pressure data, and the leakage data.

4. The method according to claim 1, wherein at least one selection from a group consisting of the first injection time interval and the second injection time interval is twenty-four hours or less.

5. The method according to claim 1, wherein the first flow rate is less than one barrel per minute of the fluid injected during the first injection time interval and the first injection time interval is less than one minute.

6. The method according to claim 5, wherein the first flow rate is in a range of 0.1 to 0.5 barrels per minute and the first injection time interval is in a range of ten to fifteen seconds.

7. The method according to claim 6, wherein the second flow rate is in a range of one to two barrels per minute and the first injection time interval is in a range of ten to fifteen seconds.

8. The method according to claim 1, further comprising:

injecting a fluid into the formation at a third flow rate greater than the second flow rate during a third time interval using the fluid injector;

measuring pressure versus time using the pressure sensor and the timer during a third test time interval after the injecting for the third injection time interval to provide third pressure data using the pressure sensor; and

estimating the property additionally using the third pressure data.

9. The method according to claim 8, wherein the third flow rate is greater than two barrels per minute of the fluid injected during the third injection time interval.

10. The method according to claim 9, wherein the third flow rate is in a range of five to seven barrels per minute.

11. The method according to claim 1, further comprising:

injecting a fluid into the formation at a fourth flow rate less than the second flow rate during a fourth time interval using the fluid injector;

measuring pressure versus time using the pressure sensor and the timer during a fourth test time interval after the injecting for the fourth injection time interval to provide fourth pressure data; and

estimating the property additionally using the fourth pressure data.

12. The method according to claim 1, wherein performing comprises injecting a fluid into the formation using the fluid injector at an integrity test flow rate that is low enough so that the fracture gradient pressure of the formation is not exceeded and monitoring pressure and temperature of the borehole versus time using the pressure sensor and the timer.

13. The method according to claim 1, further comprising:

monitoring a fluid temperature in the borehole using a temperature sensor during the first test time interval and during the second time interval; and

correcting the first pressure data and the second pressure data for fluid temperature variations using the monitored fluid temperature.

14. The method according to claim 1, further comprising:

monitoring a fluid temperature during the borehole integrity test using a temperature sensor; and

correcting the leakage data for fluid temperature variations using the monitored fluid temperature.

15. An apparatus for estimating a property of an earth formation penetrated by a borehole, the apparatus comprising:

a fluid injector configured to inject fluid through the borehole into the formation at a selected flow rate;

a pressure sensor configured to sense pressure of a fluid in the borehole;

a timer configured to measure a time interval; and

a processor configured to;

receive leakage data from a borehole integrity test conducted at a pressure less than a fracture gradient pressure of the formation using the fluid injector;

receive first pressure data comprising a pressure versus time measurement obtained using the pressure sensor and the timer during a first test time interval after injecting a fluid into the formation at a first pressure greater than the fracture gradient pressure at a first flow rate during a first injection time interval using the fluid injector;

receive second pressure data comprising a pressure versus time measurement obtained using the pressure sensor and the timer during a second test time interval after injecting a fluid into the formation at a second flow rate greater than the first flow rate during a second injection time interval using the fluid injector; and

estimate the property using the first pressure data, the second pressure data, and the leakage data.

16. The apparatus according to claim 15, further comprising a temperature sensor configured to monitor a borehole fluid temperature and wherein the processor is further configured to correct the first pressure data and the second pressure data for borehole fluid temperature variations.

17. The apparatus according to claim 15, wherein the processor is further configured to:

receive third pressure data comprising a pressure versus time measurement obtained using the pressure sensor and the timer during a third test time interval after injecting a fluid into the formation at a third flow rate greater than the second flow rate during a third time interval using the fluid injector; and

estimate the property additionally using the third pressure data.

18. The apparatus according to claim 15, wherein the processor is further configured to:

receive fourth pressure data comprising a pressure versus time measurement obtained using the pressure sensor and the timer during a fourth test time interval after injecting a fluid into the formation at a fourth flow rate that is less than the second flow rate; and

estimate the property additionally using the fourth pressure data.

19. The apparatus according to claim 15, further comprising a temperature sensor configured to monitor fluid temperature in the borehole during the first test time interval and the second test time interval and wherein the processor is further configured to correct the first pressure data and the second pressure data for fluid temperature variations using the monitored fluid temperatures

20. A non-transitory computer-readable medium comprising computer-executable instructions for estimating a property of an earth formation penetrated by a borehole by implementing a method comprising:

receiving leakage data from a borehole integrity test conducted at a pressure less than a fracture gradient pressure of the formation using a fluid injector;

receiving first pressure data comprising a pressure versus time measurement obtained using a pressure sensor and a timer during a first test time interval after injecting a fluid into the formation at a first pressure greater than the fracture gradient pressure at a first flow rate during a first injection time interval using the fluid injector;

receiving second pressure data comprising a pressure versus time measurement obtained using the pressure sensor and the timer during a second test time interval after injecting a fluid into the formation at a second flow rate greater than the first flow rate during a second injection time interval using the fluid injector; and

estimating the property using the first pressure data, the second pressure data, and the leakage data.