Better Positioning, Control of Streamers Improves Complex-Azimuth Imaging Results

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Everyone is familiar with visible light. However, other forms of light (ultraviolet) are invisible, or rather unseen, by the human eye. Shipboard (or dry-end) command-and-control systems can be thought of in a similar way. The portion of the systems that is visible involves the monitoring, coordination, and real-time correction of survey parameters such as course headings and data acquisition rates. However, just under the sea surface, unseen in-water systems (or wet) are vital to enabling complex-azimuth imaging.

Under the control of dry-end systems, these wet systems are composed of devices that generate and record seismic energy such as air guns, streamer cables and acoustic positioning devices. Of the many wet systems, perhaps the most critical enabler of complex-azimuth acquisition is the lateral (or horizontal) positioning and control of the streamer cables.

Without the ability to control the lateral movements of streamer cables, proper illumination of the target, gathering of reflected energy relative to shot events, and rendering of the final image is made more difficult. The ability to laterally move the wet acquisition system in a predictable and controlled manner means that the longer offsets and wider streamer spreads associated with complex-azimuth imaging can be accommodated without unduly increasing the risks associated with obstructions, asymmetrical streamer shapes, and cross-line bin asymmetry.

This vital enabler allows seismic contractors to expand or shrink the width of the streamer spread, uniformly align streamers with one another along the span length, and reproduce span shapes in follow-on surveys.

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