Abstract:
In recent years, optical fiber sensing systems have been applied to the acquisition of land 3C seismic, marine 4C seismic, borehole seismic, and borehole-surface joint seismic data, which has promoted the application of optical fiber sensing techniques in geophysics, especially in the field of seismic data acquisition.This paper briefly introduces optical fiber seismic data acquisition systems applied in land, marine, and boreholes around the world, and focuses on the application of the distributed acoustic sensing (DAS) technique in the acquisition, processing, and comprehensive interpretation of borehole seismic data and borehole-surface jointly acquired seismic data.Optical fiber sensing is a novel and revolutionary technique.Because of their small size, non-electrical nature, distribution, high density, multi-parameter nature, high-temperature and high-pressure resistance, full cable sensing capability, and low cost, optical fibers will bring a revolution in borehole, marine, and terrestrial geophysical data acquisition.The downhole distributed acoustic sensing (DAS) technique has been widely used in VSP data acquisition, hydraulic fracturing microseismic monitoring, and precision engineering monitoring.It can thus achieve the entire life cycle monitoring, management, and use of oil and gas wells.The large-scale application of distributed optical fiber sensing techniques in the exploration and development of oil and gas resources has extended from well to land and marine environments, from downhole 1C measurements to downhole and terrestrial 3C measurements, and from single well single parameter measurements to multi-well multi-parameter simultaneous measurements.The capability of the demodulation instrument also has been enhanced, from a single channel and single parameter system to multi-channel and multi-parameter composite demodulation systems.The application of optical fiber sensing techniques has extended from the field of seismic exploration to oil and gas reservoir development and production.The static characterization and dynamic permanent monitoring of subsurface structures based on optical fiber application gradually form the basis of optical fiber reservoir geophysical technology.In the future, the distributed three-component optical fiber acoustic sensing technology will be used to replace the conventional three-component geophone to collect high-density full-wave field three-component seismic data in the well, land (desert), and sea, which can realize high-efficiency, low-cost, and high-density three-component seismic data acquisition on land, sea, and underground.In addition, a multi-component, multi parameter and multi-channel composite modulation and demodulation instrument integrating distributed optical fiber acoustic wave, temperature, and strain sensing needs to be developed.Future directions of research include the development and mass production of special optical fibers with high temperature resistance, high Rayleigh scattering coefficient, hydrogen loss resistance and bending insensitiveness; the development of a three component distributed optical fiber acoustic wave (seismic wave) sensing data acquisition system; the development of a high-density distributed three component optical fiber seismic data processing software; research on a joint migration imaging method of well ground three component combined mining seismic data; research and development of a positioning and orientation technology, as well as development of an armored optical cable outside the casing and a supporting directional perforation optical cable anti shooting technology.In addition, with vigorous promotion and application of artificial intelligence technology in the field of optical fiber sensing, all the developments will promote the implementation of the optical fiber geophysical technology, which will achieve the optical fiber-based intelligent reservoir sensing, description, simulation and monitoring of the whole oil and gas field reservoir.Finally, these developments will lead to an intelligent optimization of development schemes and production systems, and will play an important technical support role in the construction of smart oil and gas fields in the future.