Application of ocean bottom cable as a new tool in offshore 3-D seismic data acquisition

摘要

The ocean bottom cable (OBC) seismic technology involves the deployment of some multi-sensor cables on the ocean floor to record both the velocity and pressure signals of seismic waves. The OBC method has advantage for obtaining coverage in congested producing fields clustered with platforms, pipelines and drilling rigs. In shallow waters, lakes, bays and rivers where towed source vessel operations are difficult or impossible, the OBC method comes in handy, offering a range of benefits including higher signal bandwidth, high spatial resolution, low noise, minimum down-time, design flexibility and improved near surface resolution. Dynamically positioned recording vessels are connected to several kilometers of cables deployed along predetermined lines on the ocean floor. Strapped to the cable at regular increments are multi-component (4C) receivers or dual sensors (2C) which detect seismic signals reflected from the subsurface formations. These signals are filtered, amplified, and digitised in remote electronic modules along the cables and telemetered via the cable to a recording vessel. OBC surveys were recently introduced into 3D seismic operations in offshore Niger Delta, Nigeria.