Technique Research On Pre-stack Merge Processing Of Multiple 3D Seismic Surveys

The large area regional 3-D seismic exploration has been taken as a major part in oil-gas exploitation, now. Its huge cast for large area seismic acquisition, makes it unrealistic to finish a big survey in one time, instead, multiple small 3D seismic survey acquired in different years covers the huge areas. The 3D seismic data of multiple small area survey have many disadvantages, such as large time span, multiple seismic instruments, multiple acquisition pattern, different coverage area, etc. That leads a big problem of seismic data quality. The pre-stack merge processing to 3D seismic data can overcome this disadvantages, and it is very important to study the regional geologic features in large area, to realize breakthrough in exploitation.In Gulong Sag deep part in Changjiaweizi area of Songliao Basin, the basalt is a major reservoir. It has a very complex geological structure, and inhomogeneous media distribution horizontally and vertically. That makes seismic imaging difficult, and figuring out the structure is a major issue during oil-gas exploration. The 3D seismic data of 6592.5km2 acquired in Changjiaweizi area during 1990-2006, mostly targeted to the middle-shallow layers, have obvious discrepancy. The seismic data separately processed for each small survey have different reflection energy and waveform, and leads the difficulties for tracing reflection events, figuring out structures, losing information especially on the joint between surveys. That is a major barrier to study the geological structure, basalt character and conglomerate reservoir's development. To totally recognize the structure of Gulong Sag, researches on pre-stack merge processing techniques of multiple small seismic survey, have been conducted in the paper, and four kinds of technique have been brought out, including surface model constraint static, surface consistent process, reflection energy regulation among surveys base on energy statistics and weight, wavelet shaping. The techniques of pre-stack merge processing for seismic data acquired to middle and sallow layers, has been formed, which provides reliable base for the comparative interpretation and object identification, and also provide exact recognition of regional structure in the whole region.