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WO2017178065A1 - Procédé d'augmentation de la sensibilité et de la polyvalence de capteurs das optiques - Google Patents

Procédé d'augmentation de la sensibilité et de la polyvalence de capteurs das optiques Download PDF

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Publication number
WO2017178065A1
WO2017178065A1 PCT/EP2016/058353 EP2016058353W WO2017178065A1 WO 2017178065 A1 WO2017178065 A1 WO 2017178065A1 EP 2016058353 W EP2016058353 W EP 2016058353W WO 2017178065 A1 WO2017178065 A1 WO 2017178065A1
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WO
WIPO (PCT)
Prior art keywords
optical
optical fibre
sensor
fibre
sensor head
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PCT/EP2016/058353
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English (en)
Inventor
Jakob B. HALDORSEN
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Priority to PCT/EP2016/058353 priority Critical patent/WO2017178065A1/fr
Publication of WO2017178065A1 publication Critical patent/WO2017178065A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
    • G01V1/22—Transmitting seismic signals to recording or processing apparatus
    • G01V1/226—Optoseismic systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V2210/00—Details of seismic processing or analysis
    • G01V2210/10—Aspects of acoustic signal generation or detection
    • G01V2210/16—Survey configurations
    • G01V2210/161—Vertical seismic profiling [VSP]

Definitions

  • the invention relates to a method for acquisition of seismic data, and more specifically to an optical seismic sensor system and a method for acquiring seismic profiles.
  • VSP Vertical Seismic Profiling
  • the multi-level aspect of a receiver array will allow the estimation of the delay from one receiver to the next while the wave front is passing from one end of the array to the other.
  • a 3C receiver also measures the local direction of particle motion related to components of the passing wave fields.
  • a multi-level 3C receiver array can therefore be used to find estimates of both the full waveform and the direction of propagation in 3D space of any passing plane waves, arriving either directly from the source or scattered by the formation.
  • the time delays and polarizations at the array of receivers are sufficient for identifying whether the passing wave was compressional or shear (Leaney and Esmersoy, 1989), the ray direction, and the distance along the ray back to the source, or the location of a natural or induced seismic event as the place where the compressional and shear waves coincide in time and space (e.g.,
  • DAS Distributed Acoustic Sensing
  • acoustic waves interfering with the cable and inducing strain can be monitored by means of an optical interrogator.
  • An optical interrogator is part of a surface acquisition system, and an optical sensor would not have down-hole electronics and could therefore be used at higher temperatures than an electric sensor.
  • DAS In its basic form, DAS only measures the strain changes along the axis of an optical fibre. However, by combining them with mechanically restrained devices, one can measure acceleration in directions other than the main axial direction of the fibre. These are called multi-directional sensors.
  • 3C optical sensors For commercially available three component (3C) optical sensors, each sensor is typically built up from 40 to 50 m of fibre coiled around a device which is mechanically restrained, allowing the mechanical device to translate acceleration in one particular direction to a strain in the fibre coiled around the mechanically restrained sensor device.
  • Figure 12 in US 9207339 shows an example of such a device.
  • the mechanics of a weighted core of a coil allows the coil to only move and accelerate in one particular direction, and only movement in that direction will generate strain on the fibre, the change of which is what a DAS interrogator measures.
  • the DAS interrogator will record this directional strain at the location of the sensor.
  • this strain is compared to an identical, but unstrained fibre coil.
  • the laser-light available allows up to 9 channels per fibre, i.e. three 3C sensors per fibre. For 120 levels, this would thus require 40 continuous fibres.
  • the multi-directional sensors and the fibre connecting them as one continuous fibre and read the accumulated strain through the fibre coils with a DAS interrogator.
  • VSP Vertical Seismic Profiling
  • Adding the 3C measurement will allow the resolution of the azimuthal ambiguity inherent in the DAS measurement, and this will significantly improve the capabilities both for VSP and for permanent down-hole, high-resolution, acoustic monitoring of producing oil fields.
  • Complete and finely spaced well coverage with acoustically sensitive sensors also provides continuous real time monitoring of mechanical integrity and detect early signs of abnormal well activity.
  • the invention is defined by an optical seismic sensor system for acquiring seismic data having multi-directional sensitivity comprising one continuous length of an optical fibre arranged as a distributed acoustic sensor comprising an interrogator.
  • the interrogator comprises a transmitter for transmitting optical pulses into the optical fibre, a receiver for receiving reflected optical pulses, and an interpreter for interpreting reflected optical pulses.
  • the optical seismic sensor system further comprises at least one sensor head having flexural properties and multi-directional sensitivity, and where a section of the continuous length of the optical fibre is wound onto a part of the sensor head having the flexural properties.
  • the invention is also defined by a method for acquiring seismic data by employing the optical seismic sensor system described above.
  • the present invention is a fully-optical, hybrid acoustic sensor cable, using 3C optical sensors placed at intervals along the cable measuring local acoustically- induced directional strain combined with near-continuous 1C optical DAS sensors, both measuring acoustically induced axial strain on the one and same optical fibre.
  • a system combining traditional 3C electrical sensors with 1 C optical sensors is suitable, and where a continuous optical fibre connection can be made to an offshore platform.
  • the down-hole electronics needed for the electric 3C sensors will however adversely affect the expected lifetime, especially in a higher temperature well.
  • the all-optical hybrid sensor cable according to the invention will have no electronics in the hot zone of the well, and will therefore not be affected in a significant way by high temperatures.
  • the operational temperatures are expected to exceed 200°C by a good margin.
  • FIG. 1 illustrates an optical seismic sensor system according to the invention
  • Figure 2 illustrates details of a sensor head according to one embodiment of the invention.
  • the present invention provides this system by combining two separate fibre-optical, acoustic measurement techniques on a single optical fibre. These are:
  • DAS Distributed Acoustic Sensors
  • Figure 1 illustrates an optical seismic sensor system where two different acoustic measuring techniques are combined for reducing the cost and improving the flexibility of the instrumentation installed.
  • the figure illustrates an optical seismic sensor system 10 for acquiring seismic data having multi-directional sensitivity comprising one continuous length of an optical fibre 20 arranged as a distributed acoustic sensor, an interrogator 30 with a transmitter for transmitting optical pulses into the optical fibre 20, a receiver for receiving reflected optical pulses, and an interpreter for interpreting reflected optical pulses.
  • DAS Distributed Acoustic Sensors
  • optical seismic sensor system 10 further comprises at least one sensor head 40 having flexural properties and multi-directional sensitivity, and where a section of the continuous length of the optical fibre 20 is wound onto a part of the sensor head 40 having the flexural properties.
  • the figure illustrates one embodiment of an all optical system having multidirectional measuring properties, where several multi-directional sensor heads 40 are evenly distributed along the optical fibre 20, and where sections of the continuous length of the optical fibre 20 are wound onto a part of each multidirectional sensor head 40 having flexural properties.
  • a seismic sensor system 10 according to the invention is not restricted to the four multi-directional sensor heads 40 shown in figure 1. It may be at least one, but preferably a plurality, e.g. 600 on a 9 km optical fibre 20.
  • VSP Vertical Seismic Profiling
  • 3D VSP data can be acquired on demand, and 4D images of the reservoir around the well can be generated in a timely and cost effective manner. These images will provide information on sweep efficiencies, thief zones, potential zones of early breakthrough, injection conformance, potential identification of well safety issues amongst other applications that all contribute to improvements in well efficiency and safety.
  • the multi-directional sensor heads 40 and the optical fibre 20 wound onto it act as receivers of seismic activity. With such receivers placed close to the reservoir, this method of surveillance can continuously monitor weak acoustic activities induced by the production process, allowing preventive action to be taken if critical situations should arise. Having the receivers close to the reservoir would also allow for higher-resolution imaging as the acoustic source field and the scattered field both are observed close to the imaging target. Earth movements related or unrelated to production/injection can generate small earthquakes that can only be monitored with sensors close to the micro-earthquake activity and only be located with 3C sensors.
  • a hybrid optical acoustic sensor cable according to the invention would allow the generation of 4D images of a formation around a well at lower costs when compared to surface methods. Due to the nature of fibre-optical sensing, the system will have long lifetime in higher-temperature wells and can also be installed in subsea- completed deep-water wells.
  • one embodiment of the invention defines a feature where discrete partial reflectors are implanted in the optical fibre 20.
  • Such reflectors may in one embodiment be Bragg gratings 50 that are engraved on the optical fibre 20 immediately before and after the sensor head 40. This will also reduce the required length of fibre coiled around the mechanical device. A typical reduction from 50m to 10m of fibre in the coil of each 3C point sensor is expected.
  • Figure 2 illustrates this principle where the part of the optical fibre 20 that is wound on the at least one directional sensor head 40 is provided with engraved Bragg gratings 50 immediately before and after the sensor head 40. This will allow a reduction in the length of fibre coiled around the mechanical device to typically less than 1/5. If the Bragg grating 50 is designed to reflect only a small fraction, e.g., 0.1 percent, of the laser light, this will allow hundred's of high- return 3C point sensors on one single optical fibre 20.
  • fibre-optical accelerometers can be designed with directionality and substantially higher strain response compared with a fibre encapsulated in an in- well cable.
  • Such accelerometers can be arranged in a 3C package/station suitable for high-resolution multi-component seismic imaging.
  • Appropriate design of a system according to the present invention gives higher sensitivity of 3C optical sensors compared to conventional electric acoustic sensors, and they are otherwise considered an improvement in view of electrical geophones.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

La présente invention concerne un système de capteur sismique optique 10 pour acquérir des données sismiques ayant une sensibilité multidirectionnelle comprenant une longueur continue d'une fibre optique 20 agencée en tant que capteur acoustique distribué, un interrogateur 30 avec un émetteur pour transmettre des impulsions optiques dans la fibre optique 20, un récepteur pour recevoir des impulsions optiques réfléchies, et un interpréteur pour interpréter des impulsions optiques réfléchies. Il comprend en outre au moins une tête de capteur 40 ayant des propriétés de flexion et une sensibilité multidirectionnelle, et une section de la longueur continue de la fibre optique 20 étant enroulée sur une partie de la tête de capteur 40 ayant les propriétés de flexion. L'invention concerne en outre un procédé de fourniture d'un tel système.
PCT/EP2016/058353 2016-04-15 2016-04-15 Procédé d'augmentation de la sensibilité et de la polyvalence de capteurs das optiques Ceased WO2017178065A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2016/058353 WO2017178065A1 (fr) 2016-04-15 2016-04-15 Procédé d'augmentation de la sensibilité et de la polyvalence de capteurs das optiques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2016/058353 WO2017178065A1 (fr) 2016-04-15 2016-04-15 Procédé d'augmentation de la sensibilité et de la polyvalence de capteurs das optiques

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WO2017178065A1 true WO2017178065A1 (fr) 2017-10-19

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112698385A (zh) * 2020-12-08 2021-04-23 山东省科学院激光研究所 增强型复合分布式多分量光纤检波器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120293806A1 (en) * 1999-04-09 2012-11-22 Qinetiq Limited Optical fibre sensor assembly
US20140036628A1 (en) * 2011-03-16 2014-02-06 Optasense Holdings Limited Subsurface Monitoring Using Distributed Acoustic Sensors
US20140092710A1 (en) * 2011-06-06 2014-04-03 Silixa Ltd. Method and system for locating an acoustic source
US9207339B2 (en) 2013-01-23 2015-12-08 Magi-Q Technologies, Inc. Optical seismic sensor systems and methods

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120293806A1 (en) * 1999-04-09 2012-11-22 Qinetiq Limited Optical fibre sensor assembly
US20140036628A1 (en) * 2011-03-16 2014-02-06 Optasense Holdings Limited Subsurface Monitoring Using Distributed Acoustic Sensors
US20140092710A1 (en) * 2011-06-06 2014-04-03 Silixa Ltd. Method and system for locating an acoustic source
US9207339B2 (en) 2013-01-23 2015-12-08 Magi-Q Technologies, Inc. Optical seismic sensor systems and methods

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DONGSHAN JIANG ET AL: "Fiber optic three-component seismometer", OPTICAL SENSING II, vol. 8924, 19 September 2013 (2013-09-19), 1000 20th St. Bellingham WA 98225-6705 USA, pages 89240G, XP055325262, ISSN: 0277-786X, ISBN: 978-1-62841-971-9, DOI: 10.1117/12.2029170 *
MARTIN KARRENBACH* ET AL: "Field testing a three-component fiber-optic borehole seismic sensor array", SEG TECHNICAL PROGRAM EXPANDED ABSTRACTS 2014, 5 August 2014 (2014-08-05), pages 5019 - 5023, XP055325095, DOI: 10.1190/segam2014-1366.1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112698385A (zh) * 2020-12-08 2021-04-23 山东省科学院激光研究所 增强型复合分布式多分量光纤检波器
CN112698385B (zh) * 2020-12-08 2023-04-07 山东省科学院激光研究所 增强型复合分布式多分量光纤检波器

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