CLA—Continuous Line Acquisition

Increasing efficiency by acquiring data while turning

Enabled by our Q-Marine single-sensor seismic acquisition system and DSC dynamic spread control technique, CLA significantly increases seismic vessel efficiency. Traditional seismic surveys acquire data along straight lines and then suspend acquisition as the vessel turns and runs into the next line. By shortening the lines and acquiring data during the turns, it is possible to optimize vessel use, increasing efficiency by up to 100 %, when compared to conventional methods.

In the basic implementation the vessel continues acquiring data until equipment maintenance or remedial work is required. The vessel would then stop shooting, perform the necessary maintenance and recommence operations. In a more complex implementation where conditions required extremely regular maintenance, such as barnacle cleaning, and where the line lengths and turn times were conducive to this, CLA could be used at one end of a survey and traditional vessel turns continued at the other.

What about the noise generated when shooting in a turn?

The noise levels encountered in shooting on-the-turn can vary enormously. However, our extensive experience with CLA and Coil Shooting allows WesternGeco to be confident that we can deal with the many variations seen to date. This confidence is due in no small part to the dense signal and noise sampling supplied by the Q-Marine acquisition system.

What about processing this data?

Historically, marine towed streamer data has been processed using many 2D assumptions. While this has been acceptable in the past, mainly due to the simplicity of traditional towed-marine geometries, the push to extract more from marine seismic data has resulted in a change in focus. WesternGeco applies a true 3D approach to noise attenuation and imaging. This includes multiple attenuation solutions. CLA and Coil Shooting datasets are truly 3D in nature and need a fully integrated 3D data processing approach.