羌塘盆地北羌塘坳陷上三叠统巴贡组致密储层成岩作用与孔隙演化

Diagenesis and pore evolution of tight sandstone reservoirs in Upper Triassic Bagong Formation, North Qiangtang Depression, Qiangtang Basin

程乐利 印森林 万友利 王剑 冯兴雷 李学仁 曾胜强

CHENG Leli YIN Senlin WAN Youli WANG Jian FENG Xinglei LI Xueren ZENG Shengqiang

长江大学 录井技术与工程研究院, 湖北 荆州 434023 中国地质调查局 成都地质调查中心, 成都 610081 自然资源部 沉积盆地与油气资源重点实验室, 成都 610081 西南石油大学 地球科学与技术学院, 成都 610500

Institute of Mud Logging Technology and Engineering, Yangtze University, Jingzhou, Hubei 434023, China Chengdu Geological Survey Center, China Geological Survey, Chengdu, Sichuan 610081, China Key Laboratory for Sedimentary Basin and Petroleum Resources, Ministry of Natural Resources, Chengdu, Sichuan 610081, China School of Geosciences and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China

利用物性、铸体薄片、扫描电镜、X衍射及流体包裹体测温等测试分析手段，研究了羌塘盆地北羌塘坳陷上三叠统巴贡组储层的成岩作用特征和孔隙演化过程。巴贡组砂岩总体成分成熟度和结构成熟度中等偏低，物性极为致密。主要经历了压实作用、胶结作用、溶蚀作用和交代作用，其中胶结物组分主要为硅质、黏土矿物和碳酸盐矿物，溶蚀组分为长石。根据多方面综合分析，巴贡组地层在靠近隆起带的浅埋区处于中成岩B期，坳陷内部的深埋区处于晚成岩阶段。在考虑岩石表观体积变化和压实分段的前提下，进行了不同成岩相的孔隙演化定量计算。压实作用是储层孔隙度减小的首要原因，其次为胶结作用；溶蚀作用和绿泥石衬里的形成对储层有利。

The diagenesis and pore evolution process of tight sandstone reservoirs in the Upper Triassic Bagong Formation of the North Qiangtang Depression were studied by means of physical properties, casting thin slice, SEM, X-ray-diffraction and fluid inclusion temperature measurement. The compositional maturity and structural maturity of the Bagong sandstones are moderately low. Their physical properties are extremely tight. The main diagenetic effects include compaction, cementation, dissolution and metasomatism. The cement components are mainly siliceous, clay minerals and carbonate minerals, and the dissolution component is feldspar. According to the comprehensive analysis of various characteristics, the shallow buried area near the uplift is in the middle diagenesis stage B, and the deep buried area inside the depression is in the late diagenetic stage. Under the premise of considering the apparent volume change and compaction of rock, a quantitative calculation of pore evolution of different diagenetic facies is carried out. The calculation results show that compaction is the primary cause of reservoir porosity reduction, followed by cementation, while dissolution and the formation of chlorite lining are beneficial to reservoir porosity.

中国地质调查局项目 121201010000161110;国家青年科学基金项目 41702119

https://doi.org/10.11781/sysydz202001060