川中地区中三叠统复杂构造地震资料采集处理技术效果评价

Acquisition and processing for complicated structures of Mid-Triassic in central Sichuan basin

川中地区中三叠统雷口坡组地层在其内部和下伏嘉陵江组的盐岩、膏岩等软地层的盐底辟作用以及区域 上的挤压作用共同影响下,形成了以坡坪式逆冲断层为主,密集的低幅度断弯褶皱相伴生的薄皮逆冲构造样式, 使得该区多个区块的地震资料构造成像质量不理想。雷一1亚段的白云岩层段与其上下围岩的波阻抗差较小, 地震反射表现为弱反射特征,雷一1顶面反射品质较差,反射层位难以准确识别,构造解释的难度很大。为此,在 3个不同区块内,对雷一1反射的目标处理结果及相应的采集参数进行了包括不同采集参数的二维新、老资料, 三维叠前、叠后偏移处理等在内的对比分析。结果表明,应根据雷口坡组地层的构造特征选择采集和处理技术, 即当构造形态呈密集的低幅度强烈褶皱和断裂时,必须采用三维地震勘探及叠前偏移等技术;当构造较简单时, 采用二维常规采集处理技术,即可获得较高品质的资料。

The structure styles of Middle Triassic Leikoupo formation, in central Sichuan basin, are roof slip contraction structure, which primarily is a ramp-flat thrust accompanied by close fault-bend fold with low highness. The structure styles are formed by conjunct action of regional compression and salt diaper that is caused by soft salt and gypsum within Leikoupo formation and underlying Jialingjiang formation. Analysis the processing results and corresponding field geometries for Lei11 reflection at three different blocks, including 2-D old and new data with different acquisition parameters, and 3-D data with prestack and poststack migration. We suggest that it is imperative to select suitable acquisition and processing techniques for structure characteristic of Leikoupo formation. It must take 3-D seismic exploration and prestack migration when structure is consists dense folds with low highness, it is enough to take 2-D normal seismic acquisition and processing techniques when the structure is relative simple.