塔中地区中下奥陶统碳酸盐岩岩溶结构特征与形成过程

The paleokarst system of the Lower-middle Ordovician carbonate in Tazhong area of the Tarim Basin containing large gas and oil resources has attracted extensive broad attentions due to its complicated architecture and various controlling factors. However, the understanding of different layers of paleokarst structure is not clear enough, the evolution controlled by unconformities and sea-level changes is controversial, the study on the faults superimposition and reworking is still weak. They are obstacles for further exploration of carbonate oil and gas. This project focuses on architectures and forming processes of the Middle-Lower Ordovician paleokarst system in Tazhong area of the Tarim Basin by integrating of multivariate data, including 3D seismic, well-logging data and cores. Based on the comparative analysis of outcrop sections and borehole image logs, this study aims to elucidate the complex structural characteristics and spatial distribution of paleokarst system, reveal the formation and evolution process of paleokarst system controlled by unconformities and sea-level change, explain the superposition and transformation effects of faults on paleokarst evolution, clarify the evolutionary stage of paleokarst system, establish an evolution model of complicated paleokarst system with multi-stage and multi-genesis and realize prediction of the distribution of favorable karst reservoir. The results are of great significance in future study of deep paleokarst forming process and the exploration of paleokarst reservoir.

塔中地区中下奥陶统鹰山组岩溶型储层中蕴含丰富的油气资源，其复杂的结构特征和形成过程受到学术界和石油工业界的广泛关注。随着油气勘探的深入，岩溶结构认识不清，不整合和海平面变化造成的岩溶演化期次存在争议、断裂活动对岩溶形成过程的叠加改造作用认识不够深入等问题制约了塔中地区岩溶型储层的勘探开发。本课题围绕“塔中地区中下奥陶统碳酸盐岩岩溶结构特征与形成过程”这一科学问题，基于野外露头、三维地震、测井、岩心等资料对塔中地区鹰山组碳酸盐岩岩溶开展研究。拟通过野外露头与成像测井的对比，划分岩溶结构单元，揭示岩溶结构特征及其空间展布规律，通过分析不整合、海平面变化、断裂活动等对岩溶形成过程的控制和叠加改造作用，查明岩溶结构的发育期次，建立多期次多成因叠合的岩溶模式，预测有利岩溶储集体的分布。研究结果在深层碳酸盐岩岩溶形成过程研究和岩溶型储层油气勘探实践上都具有重要的意义。

塔中地区中下奥陶统鹰山组岩溶型储层中蕴含丰富的油气资源，其复杂的结构特征和形成.过程受到学术界和石油工业界的广泛关注。随着油气勘探的深入，岩溶结构认识不清，不整合和海平面变化造成的岩溶演化期次存在争议、断裂活动对岩溶形成过程的叠加改造作用认识不够深入等问题制约了塔中地区岩溶型储层的勘探开发。本项目围绕“塔中地区中下奥陶统碳酸盐岩岩溶结构特征与形成过程”这一科学问题，基于野外露头、三维地震、测井、岩心等资料对塔中地区鹰山组碳酸盐岩岩溶开展研究。通过野外露头与成像测井的对比，划分岩溶结构单元，对鹰山组岩溶储层中发育的表生落水洞、潜流带溶蚀洞穴等进行精细的识别和刻画。分析了洞穴内部的充填序列性。通过分析不整合、海平面变化、断裂活动等对岩溶形成过程的控制和叠加改造作用，查明岩溶结构的发育期次，揭示岩溶结构特征及其空间展布规律。鹰山组岩溶发育受大规模海平面下降造成的暴露影响，岩溶高地到岩溶斜坡再到岩溶洼地的古地貌格局，促进了溶蚀性流体从高势区向低势区的自然运移，为岩溶储层的连片发育提供了良好的构造古地貌背景。断裂和内部层序界面为流体运移提供通道，同时在层序内部，沉积相提供的物质基础使岩溶储层的发育具有选择性。不整合叠加断裂发育区是鹰山组岩溶发育的有利区。研究结果在深层碳酸盐岩岩溶形成过程研究和岩溶型储层油气勘探实践上都具有重要的意义。