Microseismic event detection and location by continuous map migration

• US 20060062084A1
• Filed: 09/17/2004
• Published: 03/23/2006
• Est. Priority Date: 09/17/2004
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Drew, Julian
• Granted Patent: US 7,391,675 B2
• Time in Patent Office: Days
• US Class Current: 367/68
• CPC Class Codes: G01V 1/01 Measuring or predicting earthquakes
• CPC Class Codes: G01V 2210/123 Passive source, e.g. microseismics
• CPC Class Codes: G01V 2210/679 Reverse-time modeling or coalescence modelling, i.e. starting from receivers

Abstract

The present invention provides methods and systems for microseismic hydraulic fracture monitoring in real-time. The methods and systems of the present invention may include continuous map migration of recorded microseismic signals. The methods and systems provide robust automated simultaneous detection and location of microseismic events.

Claims

1. A method, comprising:

monitoring microseismicity, the monitoring comprising;

receiving one or more seismic signals with one or more seismic detectors;

generating a time evolving historical map of microseismic activity by spatial mapping based on the one or more seismic signals.

2. A method according to claim 1, wherein:

the receiving further comprises measuring a first of the one or more seismic signals with one detector from a single sensor location; and

the generating further comprises;

interpreting the first seismic signal separately as a measure of P-wave and S-wave;

mapping coalescence of the first seismic signal interpreted both as a measure of P-wave and S-wave.

3. A method according to claim 1, wherein:

the receiving further comprises measuring a first of the one or more seismic signals with two or more detectors from the single sensor location;

the generating further comprises;

distinguishing between P-wave and S-wave components of the first seismic signal;

mapping coalescence of the P-wave and S-wave components of the first seismic signal.

4. A method according to claim 1, wherein:

the receiving further comprises measuring a first of the one or more seismic signals with at least two detectors in different locations;

the generating further comprises mapping spatial coalescence of the first seismic signal.

5. A method according to claim 4, wherein:

the receiving further comprises measuring the first of the one or more seismic signals with at least three detectors in different locations;

the generating further comprises 2D mapping spatial coalescence of the first seismic signal.

6. A method according to claim 4, wherein:

the receiving further comprises measuring the first of the one or more seismic signals with at least four detectors in different locations;

the generating further comprises 3D mapping spatial coalescence of the first seismic signal.

7. A method according to claim 1, wherein:

the receiving further comprises measuring a first of the one or more seismic signals with at least two detectors in different locations;

the generating further comprises;

interpreting the first seismic signal separately as a measure of P-wave and S-wave;

mapping coalescence of the first seismic signal interpreted both as a measure of P-wave and S-wave;

mapping spatial coalescence of the first seismic signal from the first seismic signal received by the at least two detectors in different locations.

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

interpreting the evolving historical map and identifying microseismic events.

9. A method according to claim 8, wherein the interpreting comprises interpreting the evolving historical map at a plurality of times as a measure of seismic energy of interest generated at each of the plurality of times at points in space.

10. A method according to claim 8, further comprising reporting the microseismic events to a hydraulic fracture operator in real-time.

11. A method according to claim 1, further comprising identifying points of interest from the evolving historical map at discreet times from points on the map showing significant seismic energy sources.

12. A method according to claim 1, wherein the receiving seismic signals and generating a time evolving historical map is automated.

13. A method according to claim 1, further comprising using hash tables to store pre-computed values prior to generating the evolving historical map.

14. A method according to claim 1, wherein the spatial mapping comprises two-dimensional mapping as a function of:

a distance from an array of seismic sensors; and

position.

15. A method according to claim 1, wherein the spatial mapping comprises forward or reverse mapping.

16. A method of monitoring microseismic events, comprising:

performing a hydraulic fracture operation in a wellbore;

mapping to generate a historical map of a source of seismic energy during the hydraulic fracture operation;

detecting and locating microseismic events from the historical map.

17. A method of monitoring microseismic events according to claim 16, further comprising reporting detected and located microseismic events to an operator in real-time.

18. A method of monitoring microseismic events according to claim 16, further comprising continuously recording microseismic data generated during the hydraulic fracture operation.

19. A method of monitoring microseismic events according to claim 18, further comprising performing a continuous arrival detection transform on the microseismic data.

20. A method of monitoring microseismic events according to claim 19, wherein the continuous arrival detection transform comprises a continuous arrival detection transform for P-wave arrivals and a continuous arrival detection transform for S-wave arrivals.

21. A method of monitoring microseismic events according to claim 18, further comprising performing a continuous polarization computation of three-component seismic signals from the microseismic data.

22. A method of monitoring microseismic events according to claim 21, wherein the mapping comprises:

comparing a forward modeled P-wave arrival with the computed three-component polarization;

weighting a contribution by a match between modeled ray-direction and three-component polarization;

determining an azimuth of the microseismic event location relative to an array of seismic detectors based on the weighting.

23. A method of monitoring microseismic events according to claim 16, wherein the mapping further comprises:

measuring one or more seismic signals with one detector from a single sensor location;

interpreting the one or more seismic signals separately as a measure of P-wave and S-wave;

mapping coalescence of the one or more seismic signals interpreted both as a measure of P-wave and S-wave.

24. A method of monitoring microseismic events according to claim 16, wherein the mapping further comprises:

measuring one or more seismic signals with two or more detectors from a single sensor location;

distinguishing between P-wave and S-wave components of the one or more seismic signals;

mapping coalescence of the P-wave and S-wave components of the first seismic signal.

25. A method of monitoring microseismic events according to claim 16, wherein the mapping further comprises:

measuring one or more seismic signals with at least two detectors in different locations;

mapping spatial coalescence of the one or more seismic signals.

26. A method according to claim 25, wherein the mapping further comprises:

measuring the one or more seismic signals with at least three detectors in different locations;

2D mapping spatial coalescence of the first seismic signal.

27. A method according to claim 25, wherein the mapping further comprises:

measuring the one or more seismic signals with at least four detectors in different locations;

3D mapping spatial coalescence of the first seismic signal.

28. A method according to claim 16, wherein the mapping further comprises:

measuring one or more seismic signals with at least two detectors in different locations;

interpreting the one or more seismic signals separately as a measure of P-wave and S-wave;

mapping coalescence of the one or more seismic signals interpreted both as a measure of P-wave and S-wave;

mapping spatial coalescence of the one or more seismic signals from the first seismic signal received by the at least two detectors in different locations.

29. A method according to claim 16 wherein the mapping further comprises forward or reverse mapping.

30. A method of hydraulically fracturing a formation, comprising:

(a) pumping fluid into a wellbore;

(b) receiving seismic waveform data with a plurality of seismic detectors in the wellbore;

(c) migrating the seismic waveform data to generate an evolving historical map;

(d) interpreting the evolving historical map as a measure of seismic energy in a volume of space;

(e) identifying seismic events;

(f) changing hydraulic fracturing operation parameters based on identified seismic events.

31. A method of hydraulically fracturing a formation according to claim 30, wherein (b)-(e) are repeated continuously and reported to an operator in real time.

32. A method of hydraulically fracturing a formation according to claim 30, further comprising identifying points of interest from the evolving historical map at discreet times from points on the map showing significant seismic energy sources.

33. A method of hydraulically fracturing a formation according to claim 30 wherein the receiving seismic waveform data and migrating data into the evolving historical map are automated.

34. A method of hydraulically fracturing a formation according to claim 30, further comprising using hash tables to store pre-computed values prior to generating the evolving historical map.

38. A system for monitoring microseismic events relating to a subterranean formation surrounding a wellbore according to claim 33, further comprising a hydraulic fracture apparatus.

35. A system for monitoring microseismic events relating to a subterranean formation surrounding a wellbore, comprising:

a plurality of seismic detectors;

a computer in communication with the plurality of seismic detectors;

a set of instructions executable by the computer that, when executed, generate a time evolving historical map of microseismic activity by spatial mapping based one or more seismic signals received by the seismic detectors.

36. A system for monitoring microseismic events relating to a subterranean formation surrounding a wellbore according to claim 35, wherein the set of instructions, when executed, interpret the evolving historical map and identify microseismic events.

37. A system for monitoring microseismic events relating to a subterranean formation surrounding a wellbore according to claim 36, wherein the set of instructions, when executed, report the microseismic events to a hydraulic fracture operator in real-time.

39. A computer readable storage device encoding a program of instructions including instructions for:

generating a time evolving historical map of microseismic activity by mapping based one or more seismic signals received by one or more seismic detectors.

40. A computer readable storage device encoding a program of instructions according to claim 39, further comprising instructions for detecting and locating microseismic events from the historical map.

41. A computer readable storage device encoding a program of instructions according to claim 39, further comprising instruction for reporting detected and located microseismic events to an operator in real-time.

42. A computer readable storage device encoding a program of instructions according to claim 39, wherein the mapping comprises:

measuring one or more seismic signals with one detector from a single sensor location;

interpreting the one or more seismic signals separately as a measure of P-wave and S-wave;

mapping coalescence of the one or more seismic signals interpreted both as a measure of P-wave and S-wave.

43. A computer readable storage device encoding a program of instructions according to claim 39, wherein the mapping comprises:

measuring one or more seismic signals with at least two detectors in different locations;

mapping spatial coalescence of the one or more seismic signals.