Research And Application Of Fine 3D Seismic Acquisition Technique In Liaohe Oilfield

The characteristic of normal 3D seismic data in Liaohe oilfield is as below: the data resolution is lower, could not be applied for exploration of complicate faults and lithology. The depth imaging is bad, contraction form is unclear. It is difficult to distinguish fault location and connection of layers. S/N in lava area is lower, reflection energy in deepest layer is weak. The data in part areas is imperfect.The dissertation studies and discusses fine 3D seismic acquisition technique on the basis of analyzed normal seismic data and the methods of seismic acquisition. The fine seismic is different with traditional high resolution seismic, such as: "four small"(small layout, small receiver interval, small array distance, and small dynamite), "three high"(high frequency geophone, high fold number, high sampling interval), "double down holes "(down hole explosive and receiving). The guidance of fine seismic acquisition technique is that the seismic data has wider frequency band, also the seismic data of each frequency and higher frequency in specially has higher resolution.The technique was actually applied in Damingtun sag , west part sag of Liaohe oilfield, and other oilfields. The result is as below:1. Geometry design focused to the target. The first step of the design of fine 3D seismic acquisition technique is reached to the request of geological target, select the geometry scientifically. In developing time of computer hardware and software technology, the construction of different layers in underground is modeled in room with own seismic data and geological research production. The acquisition method is much scientific, reasonable and actual.2. Fine investigation for lower velocity layer. The best exploded lithology, source hole depth, and source point is searched on the basis of exploded technology of lithology and construction in lower velocity layer. Consequently seismic data with wide frequency band and higher main frequency is exploded. The basis way of pattern source points is found in Liaohe basin according to pattern holes exploded technology.3. Large numbers of dynamite types, different speed and density of dynamite are tested and analyzed; therefore the best type of dynamite is selected for seismic operation area. The parameter of source and receiver are excellently selected.4. The geometry system with large numbers of receiver channels and wide azimuth is applied. Upright geometry of normal 3D seismic is replaced by gradient geometry of fine 3D seismic, acquisition "foot image" is reduced, and artificial frequency is suppressed. The seismic data quality is studied and analyzed in real time by advanced analyses software and the best acquisition technology and methods are adapted in time. Therefore the fine 3D seismic quality is awfully improved, and satisfied for the request of second explosive and developing in aged oilfield.