琼东南盆地中生代潜山成储主控因素及分布规律

Factors controlling the formation and distribution of Mesozoic buried hill reservoirs in the Qiongdongnan Basin

侯明才 何小胡 金秋月 曹海洋 贺礼文 阙有缘 陈安清

Mingcai HOU Xiaohu HE Qiuyue JIN Haiyang CAO Liwen HE Youyuan QUE Anqing CHEN

中国海域盆地潜山已成为重要的勘探新领域。琼东南盆地中生代潜山勘探钻揭多个含气构造，但未获得规模性气藏发现。究其原因，储层成因机制和分布规律是制约潜山勘探大发现的瓶颈。基于琼东南盆地已有钻井、岩心、薄片和地球物理资料，研究了琼东南不同构造带潜山储层的发育特征，并探究了潜山储层的成因机制。结果表明：①储集空间主要是构造裂缝，前新生代的印支期和燕山期逆冲挤压构造是成缝关键，相关的先存主断层为潜山分带结构形成奠定了基础，新生代拉张构造活动使先存网状断裂体系活化；②以长英质矿物为主的基岩是最有利的储集岩，多期流体作用有效改造了潜山储层质量，并促成了潜山储层的垂向分带性；③琼东南盆地中生代潜山构造带可划分为南部双层强构造改造型潜山、中部三层风化-构造改造型潜山及北部准单层弱风化改造型潜山；④经历印支期构造活动的老基岩更有利于优质潜山储层发育，邻近凹陷周缘的潜山更有利于形成大型气藏。

Buried hills are emerging as an important exploration target in the sedimentary basins offshore China. Despite the successful drilling of several gas-bearing prospects in the Mesozoic buried hills in Qiongdongnan Basin， there is a lack of research on the primary factors controlling oil and gas accumulation， and no large-scale gas reservoirs have been discovered so far. Clarifying the development characteristics and genetic mechanisms of these reservoirs is crucial for advancing buried hill exploration in this region. This paper examines the development characteristics of buried hill reservoirs across different structural belts in the Qiongdongnan Basin using existing drilling， core， thin section， and geophysical data. The results indicate that structural fractures are the primary reservoir space， with thrusting event of the pre-Cenozoic Indosinian and Yanshanian playing a key role in fracture formation. The presence of preexisting main faults provided the foundation for the formation of the buried hills and the Cenozoic extension activities reshaped the fracture systems. Bedrocks dominated by felsic minerals are the favorable reservoir rocks， with multi-stage fluid action effectively improving the quality of buried hill reservoirs and contributing to their vertical zoning. The Mesozoic buried hill structural belt of Qiongdongnan Basin can be classified into a double-layer type of buried hill intensively modified by tectonism in the south， a three-layer type of buried hill modified jointly by weathering and tectonism in the middle， and a single-layer type of buried hill weakly modified by weathering in the north. The study also shows that ancient bedrocks that experienced the Indosinian tectonic activity are more favorable for the development of high-quality buried hill reservoirs， while the buried hills near the periphery of the depression are more conducive to the formation of large gas reservoirs.

10.11743/ogg20230309