A Fibre Optic Multi-Component Seismic Acquisition System for Permanent Reservoir Monitoring

Abstract

Abstract A fibre optic multi-component seismic acquisition system for permanent installation on the sea floor has been developed and tested. Permanent seafloor seismic installations are an alternative to other marine seismic acquisition methods for time-lapse (or 4D) seismic reservoir monitoring. 4D seismic can assist reservoir engineers to monitor fluid injection and drainage of the reservoir, and help determine detailed reservoir fluid-flow models. The new fibre optic system uses a Dense Wavelength Division Multiplexing telemetry scheme to optically power the seismic sensors. This methodology allows for channel counts in excess of 2000 per cable. Furthermore, the fibre optic system has a very broad processing bandwidth that yields exceptional dynamic range (> 140dB), which together with low channel crosstalk and distortion, will produce high quality seismic images. The multi-component sensors at each receiver station are optical transducers made using Michelson interferometers. Avoiding in-sea electronics creates a safe and robust system, and utilisation of standard telecommunication components ensures an economically viable reservoir monitoring tool. Field trials conducted in hydrocarbon provinces demonstrate the reliability and excellent response of the fibre optic system to the seismic source. The seismic data acquired by the new fibre optic acquisition system show good correlation with data acquired in parallel using a conventional electrical seafloor acquisition system.