川西坳陷XC构造带雷口坡组顶部风化壳储层预测

Prediction of Middle Triassic Leikoupo Weathering Crust Reservoir in XC Structure Belt, Chuanxi Depression

四川盆地川西坳陷XC构造带的中三叠统雷口坡组地层埋深大,地质条件复杂,采用任何单一的技术方法皆难于准确预测雷口坡组顶部风化壳洞缝型储层的分布。在明确沉积储层特征的基础上,依据储层地震响应特征,采用波形分类、地震属性、相干体分析、波阻抗反演等多种技术方法进行储层有利相带预测,建立了一套适合雷口坡组顶部风化壳洞缝型储层的预测技术方法序列。预测结果表明,雷口坡组顶部风化壳洞缝型储层主要分布于XQ构造—XC构造—WX构造一带,综合评价为储层发育有利区;其次分布在HXC构造—FG构造一带,综合评价为储层发育较有利区,其余地区储层相对较差。

A vuggy/fissuring weathering-crust reservoir develops in the uppermost part of the middle Triassic Leikoupo Formation in the XC Structure Belt in Chuanxi Depression, Sichuan Basin. The XC Structural Belt is comprised of a number of anticlines such as XQ, XC, HXC, LXC, WX, GMZ, and FG anticlines. Because of deep bury and complex geological conditions of the structure belt, it is difficult to predict accurately the sedimentary facies distribution of the reservoir by using any single technical method. Based on the sedimentation characteristics and the seismic response characteristics, a series of compatible technical methods which include waveform classification, seismic attributes, coherence analysis and impedance inversion are set up and used to predict the distribution of favorable sedimentary facies in the Leikoupo weathering-crust reservoir. According to the prediction result and the comprehensive evaluation, it is shown that the XQ-XC-WX anticline zone is favorable for reservoir development, the HXC-FG anticline zone is next and the rest anticlines are relatively poor.