摘要:
A Distributed Acoustic Sensing (DAS) fiber optical assembly comprises adjacent lengths of optical fiber A, B with different directional acoustic sensitivities, for example by providing the first length of optical fiber A with a first coating 35, such as acrylate, and the second length of optical fiber B with a second coating 36, such as copper, wherein the first and second coatings 35 and 36 may be selected such that the Poisson's ratio of the first length of coated fiber A is different from the Poisson's ratio of the second length of coated fiber B. The different Poisson's ratios and/or other properties of the adjacent lengths of optical fiber A and B improve their directional acoustic sensitivity and their ability to detect broadside (radial) acoustic waves.
摘要:
A method for obtaining information about a hydraulic fracturing operation in a fracture zone in a well, comprises a) providing at least one acoustic sensor in the well and at least one acoustic source, b) injecting fracturing fluid into the well so as to cause fractures in a fracture zone in the surrounding formation, c) using the acoustic source to send an acoustic signal and using the acoustic receiver to receive the signal, d) repeating step c) at least once, and e) processing the received signals using a microprocessor so as to obtain information about the fractures. The source may be at the earth's surface or in a second well. Step e) may comprise measuring first-arriving acoustic waves or measuring reflected or diffracted acoustic waves. The information gained in step e) may be used to control the injection of fracturing fluid or detect out-of-zone water injection.
摘要:
A Distributed Acoustic Sensing(DAS) fiber optical assembly comprises adjacent lengths of optical fiber A, B with different directional acoustic sensitivities, for example by providing the first length of optical fiber A with a first coating 35, such as acrylate, and the second length of optical fiber B with a second coating 36, such as copper, wherein the first and second coatings 35 and 36 may be selected such that the Poisson's ratio of the first length of coated fiber A is different from the Poisson's ratio of the second length of coated fiber B. The different Poisson's ratios and/or other properties of the adjacent lengths of optical fiber A and B improve their directional acoustic sensitivity and their ability to detect broadside (radial) acoustic waves.
摘要:
A method for obtaining seismic information about a subsurface formation using at least one fiber optic cable having its proximal end coupled to a light source and a photodetector comprises: transmitting into the cable at least one light pulse; receiving at the photodetector a first and second light signals indicative of the physical status of at least one first cable section and at least one second cable section, respectively, wherein the first and second sections are selected so as to provide first and second information items, respectively; optionally, further processing at least one of the first and second information items so as to produce derivative information; and outputting at least one of the first, second, and derivative information items to a display; wherein the second item differs from the first item in at least one aspect selected from the group consisting of: resolution, area, and location.
摘要:
A method for obtaining seismic information about a subsurface formation using at least one fiber optic cable having its proximal end coupled to a light source and a photodetector comprises: transmitting into the cable at least one light pulse; receiving at the photodetector a first and second light signals indicative of the physical status of at least one first cable section and at least one second cable section, respectively, wherein the first and second sections are selected so as to provide first and second information items, respectively; optionally, further processing at least one of the first and second information items so as to produce derivative information; and outputting at least one of the first, second, and derivative information items to a display; wherein the second item differs from the first item in at least one aspect selected from the group consisting of: resolution, area, and location.
摘要:
A method for obtaining information about a hydraulic fracturing operation in a fracture zone in a well, comprises a) providing at least one acoustic sensor in the well and at least one acoustic source, b) injecting fracturing fluid into the well so as to cause fractures in a fracture zone in the surrounding formation, c) using the acoustic source to send an acoustic signal and using the acoustic receiver to receive the signal, d) repeating step c) at least once, and e) processing the received signals using a microprocessor so as to obtain information about the fractures. The source may be at the earth's surface or in a second well. Step e) may comprise measuring first-arriving acoustic waves or measuring reflected or diffracted acoustic waves. The information gained in step e) may be used to control the injection of fracturing fluid or detect out-of-zone water injection.