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公开(公告)号：EP4345508A2
公开(公告)日：2024-04-03
申请号：EP24158247.7
申请日：2015-05-15
申请人： Silixa Ltd.
IPC分类号： G01V1/44
摘要： Embodiments of the invention provide a downhole device that is intended to be co-located with an optical fiber cable to be found, for example by being fixed together in the same clamp. The device has an accelerometer or other suitable orientation determining means that is able to determine its positional orientation, with respect to gravity. A vibrator or other sounder is provided, that outputs the positional orientation information as a suitable encoded and modulated acoustic signal. A fiber optic distributed acoustic sensor deployed in the vicinity of the downhole device detects the acoustic signal and transmits it back to the surface, where it is demodulated and decoded to obtain the positional orientation information. Given that the device is co-located with the optical fiber the position of the fiber can then be inferred. As explained above, detecting the fiber position is important during perforation operations, so that the fiber is not inadvertently damaged.
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公开(公告)号：EP3933351A1
公开(公告)日：2022-01-05
申请号：EP21187115.7
申请日：2016-08-05
申请人： Silixa Ltd. , Chevron U.S.A. Inc.
摘要： Embodiments of the invention provide a "tool-kit" of processing techniques which can be employed in different combinations depending on the circumstances. For example, flow speed can be found using eddy tracking techniques as will be described, or by using speed of sound measurements. Moreover, composition can be found by using speed of sound measurements and also by looking for turning points in the k - ω curves, particularly in stratified multi-phase flows. Different combinations of the embodiments to be described can therefore be put together to provide further embodiments, to meet particular flow sensing requirements, both on the surface and downhole. Once the flow speed is known, then at least in the case of a single phase flow, the flow speed can be multiplied by the interior cross-sectional area of the pipe to obtain the flow rate. The mass flow rate can then be obtained if the density of the fluid is known, for example once the composition has been determined.
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公开(公告)号：EP3044554A1
公开(公告)日：2016-07-20
申请号：EP14762076.9
申请日：2014-09-04
申请人： Silixa Ltd
CPC分类号： G01H9/004 , G01L1/242 , G01M7/00 , G02B6/4405 , G02B6/4415
摘要： Embodiments of the present invention address aliasing problems by providing a plurality of discrete acoustic sensors along a cable whereby acoustic signals may be measured in situations where the fiber optic cable has not been secured to a structure or area by a series of clamps, as described in the prior art. Acoustic sampling points are achieved by selectively enhancing the acoustic coupling between the outer layer and the at least one optical fiber arrangement, such that acoustic energy may be transmitted selectively from the outer layer to the at least one optical fiber arrangement. The resulting regions of acoustic coupling along the cable allow the optical fiber to detect acoustic signals. Regions between the outer layer and the at least one optical fiber arrangement that contain material which is acoustically insulating further this enhancement since acoustic waves are unable to travel through such mediums, or at least travel through such mediums at a reduced rate.
摘要翻译： 本发明的实施例通过沿着电缆提供多个离散声学传感器来解决混叠问题，由此可以在光缆未被一系列夹具固定到结构或区域的情况下测量声学信号，如 现有技术。 声学采样点通过选择性地增强外层和至少一个光纤布置之间的声学耦合来实现，使得声能可以选择性地从外层传输到至少一个光纤布置。 沿电缆产生的声学耦合区域允许光纤检测声音信号。 由于声波不能穿过这些介质，或者至少以降低的速率穿过这些介质，所以外层和至少一个光纤装置之间的区域进一步声学绝缘地进行声学隔离。
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公开(公告)号：EP4345508A3
公开(公告)日：2024-06-05
申请号：EP24158247.7
申请日：2015-05-15
申请人： Silixa Ltd.
IPC分类号： G01V11/00 , G01V1/44 , E21B47/022 , E21B47/0224
CPC分类号： G01V1/44 , G01V11/002 , E21B47/0224
摘要： Embodiments of the invention provide a downhole device that is intended to be co-located with an optical fiber cable to be found, for example by being fixed together in the same clamp. The device has an accelerometer or other suitable orientation determining means that is able to determine its positional orientation, with respect to gravity. A vibrator or other sounder is provided, that outputs the positional orientation information as a suitable encoded and modulated acoustic signal. A fiber optic distributed acoustic sensor deployed in the vicinity of the downhole device detects the acoustic signal and transmits it back to the surface, where it is demodulated and decoded to obtain the positional orientation information. Given that the device is co-located with the optical fiber the position of the fiber can then be inferred. As explained above, detecting the fiber position is important during perforation operations, so that the fiber is not inadvertently damaged.
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公开(公告)号：EP4354092A2
公开(公告)日：2024-04-17
申请号：EP24153276.1
申请日：2021-02-19
申请人： Silixa Ltd.
IPC分类号： G01D5/353
CPC分类号： G01K11/32 , G01H9/004 , G01V1/208 , G01V1/226 , G01V1/42 , G01D5/35354 , E21B47/135 , E21B47/114 , E21B47/06
摘要： A long range optical fiber sensor such as a distributed acoustic sensor has a sensing fiber located remotely from the interrogator, with a length of transport fiber path connecting the two. Because no sensing is performed on the transport fiber then the pulse repetition rate from the interrogator can be high enough such that the pulse repetition rate and pulse power are optimised according to the sensing fiber length and hence sensing frequency response and sensitivity are also optimised according to the sensing fiber length. In further embodiments fiber amplifiers such as erbium doped fiber amplifiers may be included in line in the transport fiber path, typically located just before the sensing fiber in the direction of pulse travel from the interrogator, to help restore the pulse signal power before it enters the sensing fiber. In yet further embodiments at least one Raman pump source can be provided to inject light pulses on to the transport fiber at a Raman pump wavelength to stimulate the generation of signal photons at the interrogator pulse wavelength via the stimulated Raman scattering (SRS) phenomenon. This helps to maintain the forward pulses and backscatter/reflection signals as they traverse the transport fiber path to and from the sensing fiber.
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公开(公告)号：EP3786589A1
公开(公告)日：2021-03-03
申请号：EP20175508.9
申请日：2016-03-07
申请人： Silixa Ltd.
摘要： Embodiments of the invention provide an improved optical fiber distributed acoustic sensor system that makes use of a specially designed optical fiber to improve overall sensitivity of the system, in some embodiments by a factor in excess of 10. This is achieved by inserting into the fiber weak broadband reflectors periodically along the fiber. The reflectors reflect only a small proportion of the light from the DAS incident thereon back along the fiber, typically in the region of 0.001% to 0.1%, but preferably around 0.01% reflectivity per reflector. In addition, to allow for temperate compensation to ensure that the same reflectivity is obtained if the temperature changes, the reflection bandwidth is relatively broadband i.e. in the region of +/- 3nm from the nominal laser wavelength. In some embodiments the reflectors are formed from a series of fiber Bragg gratings, each with a different center reflecting frequency, the reflecting frequencies and bandwidths of the gratings being selected to provide the broadband reflection. In other embodiments a chirped grating may also be used to provide the same effect. In preferred embodiments, the reflectors are spaced at half the gauge length i.e. the desired spatial resolution of the optical fiber DAS.
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公开(公告)号：EP4086591A1
公开(公告)日：2022-11-09
申请号：EP22180716.7
申请日：2016-08-05
申请人： Silixa Ltd. , Chevron U.S.A. Inc.
摘要： Embodiments of the invention provide a "tool-kit" of processing techniques which can be employed in different combinations depending on the circumstances. For example, flow speed can be found using eddy tracking techniques as will be described, or by using speed of sound measurements. Moreover, composition can be found by using speed of sound measurements and also by looking for turning points in the k - ω curves, particularly in stratified multi-phase flows. Different combinations of the embodiments to be described can therefore be put together to provide further embodiments, to meet particular flow sensing requirements, both on the surface and downhole. Once the flow speed is known, then at least in the case of a single phase flow, the flow speed can be multiplied by the interior cross-sectional area of the pipe to obtain the flow rate. The mass flow rate can then be obtained if the density of the fluid is known, for example once the composition has been determined.
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