高石梯-磨溪地区灯影组四段岩溶古地貌分布特征及其对气藏开发的指导意义

基于四川盆地高石梯-磨溪地区三维地震和完钻井资料,结合高分辨率法、层拉平法、残厚法和印模法的优点,采用双界面法对高石梯-磨溪地区震旦系灯影组四段（灯四段）岩溶古地貌进行恢复。灯四段岩溶古地貌包括岩溶低地、岩溶斜坡和岩溶台地3种一级古地貌单元以及陡坡、缓坡、台坡、台面、洼地、沟谷和残丘7种二级古地貌单元。灯四段岩溶古地貌表现为"两沟三区、北缓南陡"的特征,同时高石梯地区发育台坡、台面和残丘3种古地貌单元,磨溪地区主体发育缓坡和台面,台地内部发育台面、洼地和残丘。台坡、台面和斜坡微地貌单元岩溶发育程度好,优质储层发育,完钻井效果较好,高石梯和磨溪地区差异性明显。研究结果表明,岩溶古地貌对高产井控制作用明显,下一步需要精细刻画沟谷分布,论证断层及古沟槽对古地貌分布的控制作用、分区建立古地貌划分标准,评价台地内部优势微地貌单元分布,支撑建产有利区筛选和目标开发井位优化,从而为高石梯-磨溪地区震旦系气藏快速建产和长期稳产提供保障。

Distribution features of ancient karst landform in the fourth Member of the Dengying Formation in the Gaoshiti-Moxi region and its guiding significance for gas reservoir development

Based on the 3D seismic and well completion data in the Gaoshiti-Moxi region of Sichuan Basin, this study restores the ancient karst landform of the fourth member of the Sinian Dengying Formation in Gaoshiti-Moxi region using the dual interface method in combination with advantages of the high-resolution method, bedding flattening method, residual thickness method, and impression method. The ancient karst landform of the fourth Member of Dengying Formation is composed of three first-order ancient landform units of karst lowland, karst slope, and karst platform and seven second-order ancient landform units of steep slope, gentle slope, platform slope, platform surface, depression, gully, and monadnock. The ancient karst landform in the fourth member of Dengying Formation has the characteristics of "two ditches and three regions, gentle in the north and steep in the south". Three ancient landform units of platform slope, platform surface and monadnock are developed in Gaoshiti. Gentle slope and platform surface are developed in the main body of Moxi region butplatform surface, depression and monadnock are developed inside the platform. In the micro-geomorphic units of platform slope, platform surface and slope, high-quality reservoirs are well developed, andit has achieved good effect of drilled wells. There are obvious differences between Gaoshiti and Moxi areas. The results show that the ancient karst landform has obvious control effect onhigh-yield well. The next step is to finely characterize the distribution of gullies, argue the control of faults and paleo-grooves on the distribution of ancient landform, establish theclassification standard of ancient landforms in different regions, and evaluate the distribution of dominant micro-topographic units in the study area to support the selection of favorable production regions and optimization of the target development well locations, so as to ensure the rapid production and long-term stable production of Sinian gas reservoirs in the Gaoshiti-Moxi region.