Research On Complex Fault Block Geological Imaging Technique In Yongxin Area

Yongxin Area belongs to complex fault block zone with multi sets of fracture systems, which is characteristic of multi faults, small fault block, short extension and narrow band. With continuous improvement of the exploration maturity, seismic exploration targets are more and more complex, and the exploration difficulty is also increasing. Whereas, the old data presently used exhibits the problems of low dominant frequency, narrow frequency band, low imaging precision and S/N, unclear breakpoints, and it is difficult to distinguish to the fracture system. Thus, it can not satisfy the demand of fine geological interpretation, such contradiction stands out especially on aspect of oilfield development.Based on the data of high precision 3D in Yongxin Area acquired in 2007, the paper systematically research that resolution of the data is effectively increase, geological imaging result is dramatically improved by means of adopting concrete technological measures, and as a result, purpose of the exploration development demand in the area is achieved, and its application effect is confirmed from the processing of real data.From particular analysis of the features of old and new data and problems existed in present development, the paper discusses and analyzes the influence of statics on resolution, develops and applies tomography inversion static based on data constraint for the first time in Shengli plain prospect area, and consequently, surface consistent difference resulted from weathering is well resolved. Applying the technique, event continuity is enhanced, and S/N is increased, at the same time, high frequency component is effectively protected, all of these provide foundation for improving resolution later. On the aspect of improving resolution, techniques of frequency compensation of optimizing Q-factor and post-stack frequency extension based on well constraint are applied, and further improve resolution of interest formation from pre-stack and post-stack respectively.Velocity is one of the important processing parameters. The paper analyzes the influence of velocity on complex fault block imaging and the influence of NMO correction error resulted from insufficient velocity precision on high frequency component, and provides velocity analysis and model building techniques of multi parameters constraint to improve velocity precision by means of utilization factor constraint, horizontal velocity slice constraint, vertical velocity slice constraint, constant velocity scanning constraint, geological structure interpretation constraint. Geological imaging results of stack and migration from real data confirm the good effect of the technique.Finally, the paper discusses that the new data is much best than old data by means of combined application of improving geological imaging techniques in complex fault block, the final pre-stack time migration section is characteristic of reasonable and reliable imaging, obvious features of wave group, clear breaking point of small fault and small fault block, high S/N and resolution, dominant frequency band and effective frequency width of the main interest interval extent of 37-39Hz than that of old data.Research result indicates that the innovative technique proposed in the paper can satisfy the fine seismic interpretation requirement and exploration & development demand in complex fault block area.