Streamers versus Stationary Receivers (1997)

Abstract Marine 3D seismic data acquisition technology is progressing rapidly. On the one hand, there has been a very rapid increase in the number of streamers that can be towed by modern seismic vessels, and on the other hand, the variety of stationary-receiver (sea-bed) systems is mushrooming. As a consequence, 3D seismic acquisition surveys may be carried out using quite different techniques, and the question which technique is most appropriate for a given problem needs to be addressed. This paper reviews pros and cons of the various techniques. One criterion for comparison is the magnitude of the geometry imprint. It is argued that a geometry imprint is always present, but that it might be easier to minimize in seabed seismic. The use of streamers always involves the choice of shooting direction. Some geologic features can be imaged better if such a choice does not have to be made. The multisource, multi-streamer and sometimes multi-boat operationsare very efficient, but they also suffer from discontinuities in the crossline offset, leading to irregular illumination of the subsurface. In stationary-receiver techniques sources and receivers are decoupled, allowing the use of alternative acquisition geometries. Generally speaking, control of the actual receiver positions is better with the stationary-receiver techniques than with streamer acquisition with its (as yet) uncontrollable feathering. The vertical hydrophone cable technique is a VSP like technique with a series of hydrophones strung along a cable anchored to the sea bottom.. At present, the most common stationary-receiver technique is the dual-sensor technique which combines a hydrophone and a vertical geophone in Eventually, these techniques will expand the scope of the seismic method with the exploitation of the information carried by shear wave data. Introduction Marine 3D seismic data acquisition technology is progressing rapidly. On the one hand, there has been a very rapid increase in the number of streamers that can be towed by modern seismic vessels, and on the other hand, the variety of stationary-receiver (sea-bed) systems is mushrooming. As a consequence, 3D seismic acquisition surveys may be carriedout using quite different techniques, and the question which technique is most appropriate for a given problem needs to be addressed. This paper reviews pros and cons of the varioustechniques. There is a great deal of similarity between a 2D grid of seismic lines acquired either on land or offshore. In both cases sources and receivers are arranged along coinciding straight lines leading to seismic traces all having the same shotlreceiver azimuth within one seismic line. The maindifference - as far as geometry is concerned - is that in streamer acquisition an end-on geometry is used whereas in land data acquisition a center-spread geometry is possible. With the advent of 3D acquisition, marine and land data acquisition geometries started to diverge. In marine acquisition, 3D was most efficiently achieved by repeating the2D geometry, whereas on land sources and receivers can be decoupled so that other geometries such as orthogonal and zigzag geometries are also feasible, and in fact more cost effective.