基于深水沉积学原理的地震属性分析新思路

A New Seismic Attribute Analysis with Deep-Water Sedimentation

针对深水勘探钻井及测井资料不足但地震资料相对丰富的特点,在深水沉积学理论的指导下,明确了各类沉积单元的典型识别特征,优选出对特定识别特征最为敏感的地震属性以实现对深水沉积单元的表征。该研究将深水沉积单元的侧向边界划分为渐变型、突变型和标志物型3种。针对不同的边界,根据地震属性的数理意义进行属性优选并为特定地震属性赋予地质含义。研究结果表明:渐变边界处砂质含量的逐渐降低即为其典型识别特征,可通过振幅类属性加以识别;突变边界两侧地震波形具有不连续性,可根据相干属性识别;标志物边界如块体搬运沉积底部的侵蚀擦痕边界,可通过方位角属性加以识别。深水环境下,加积型水道和朵叶均具有渐变边界;侵蚀型水道与两侧被侵蚀地层间存在突变边界;而块体搬运沉积则由于底部侵蚀擦痕的存在而具有标志物边界。该研究从沉积学角度为深水地震勘探提供了一种新的分析思路。

Considering the limited exploration drilling and logging data and relatively abundant seismic data, the typical identification patterns of different sedimentary units were clarified under the guidance of deep-water sedim entology theory. The most sensitive seismic attributes for the typical identification pattern were optimized to charac terize the deep-water sedimentary unit. The lateral boundary of deep-water sedimentary unit is divided into 3 types according to this research, namely gradation type, mutant type and marker type. The seismic attributes were opti mized according to the mathematical meaning of seismic attributes for different boundaries, which also gives geolog ical implications for specific seismic attributes. Research indicates that the gradation type is featured by a gradual decrease of sandy content around at its boundary. The mutant type is featured by discontinuous seismic waveforms at its boundary, which can be identified according to the coherent properties. In the marker boundary, the erosion scratch boundary at the bottom of the block transformation deposition can be identified by the azimuthal property. Both the aggrading channel and lobe are featured by grading boundary in deep - water environment. The erosion channel and the eroded strata on both sides are featured by abrupt boundaries. The block deposition is featured by marker boundary due to the presence of bottom erosion scratch. This research could provide a new analytical ap proach for the deep-water seismic exploration from the perspective of sedimentology.