Method of obtaining improved geophysical information about earth formations
First Claim
1. A method of obtaining geophysical information about subsurface formations, comprising:
- (a) permanently deploying a plurality of fiber optic sensors in a survey wellbore, each said sensor having a fiber optic element detecting a seismic wave;
(b) using said fiber optic sensors for detecting seismic waves traveling through the subsurface formations; and
(c) processing the detected seismic waves to obtain geophysical information about the subsurface formation.
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Accused Products
Abstract
The present invention provides a method for forming wellbores. In one method, one or more wellbores are drilled along preplanned paths based in part upon seismic surveys performed from the surface. An acoustic transmitter conveyed in such wellbores transmits acoustic signals at a one or more frequencies within a range of frequencies at a plurality of spaced locations. A plurality of substantially serially spaced receivers in the wellbores and/or at s receive signals reflected by the subsurface formations. The sensors may be permanently installed in the boreholes and could be fiber optic devices. The receiver signals are processed by conventional geophysical processing methods to obtain information about the subsurface formations. This information is utilized to update any prior seismographs to obtain higher resolution seismographs. The improved seismographs are then used to determine the profiles of the production wellbores to be drilled. Borehole seismic imaging may then be used to further improve the seismographs and to plan future wellbores. Cross-well tomography may be utilized to further update the seismographs to manage the reservoirs. The permanently installed sensors may also be used to monitor the progress of fracturing in nearby wells and thereby provide the necessary information for controlling fracturing operations.
115 Citations
30 Claims
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1. A method of obtaining geophysical information about subsurface formations, comprising:
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(a) permanently deploying a plurality of fiber optic sensors in a survey wellbore, each said sensor having a fiber optic element detecting a seismic wave;
(b) using said fiber optic sensors for detecting seismic waves traveling through the subsurface formations; and
(c) processing the detected seismic waves to obtain geophysical information about the subsurface formation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
(i) placing a second plurality of spaced seismic receivers outside the survey wellbore;
(ii) detecting said seismic waves in the second plurality of receivers and generating signals responsive to such detected seismic waves; and
(iii) combining the signals from the first and second pluralities of receivers to obtain the geophysical information.
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12. The method of claim 11 wherein said second plurality of spaced seismic receivers comprises fiber optic sensors.
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13. The method of claim 1 further comprising:
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(i) subsequently conducting seismic surveys to obtain secondary information about the subsurface formation, and (ii) combining the obtained geophysical information and the secondary geophysical information to obtain an enhanced map of the subsurface formations.
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14. The method of claim 1 further comprising producing a cross-well seismograph from the detected seismic waves.
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15. The method of claim 1 wherein said survey wellbore follows a predetermined wellpath as a sidebore from a production wellbore.
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16. A method of obtaining geophysical information about subsurface formations, comprising:
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(a) deploying a plurality of fiber optic sensors in a first survey wellbore, each said sensor having a fiber optic element for detecting a seismic wave;
(b) generating seismic waves in the subsurface using at least one transmitter in a second survey wellbore and using said fiber optic sensors for detecting said generated seismic waves traveling through the subsurface formations; and
(c) processing the detected seismic waves to obtain geophysical information about the subsurface formation. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
(i) using a second plurality of spaced seismic receivers outside the first survey wellbore for detecting said seismic waves reflected by earth'"'"'s formations and generating signals responsive to such detected seismic waves; and
(iii) combining the signals from the fiber optic sensors and the seismic receivers to obtain the geophysical information.
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26. The method of claim 25 wherein said second plurality of spaced seismic receivers comprises fiber optic sensors.
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27. The method of claim 16 further comprising:
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(i) subsequently conducting seismic surveys to obtain secondary information about the subsurface formation, and (ii) combining the obtained geophysical information and the secondary geophysical information to obtain an enhanced map of the subsurface formations.
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28. The method of claim 16 further comprising producing a cross-well seismograph from the detected seismic waves.
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29. The method of claim 16 wherein at least one of said first and second survey wellbores follows a predetermined wellpath as a sidebore from a production wellbore.
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30. The method of claim 18 wherein said source of light is downhole.
Specification