柴达木盆地英西地区S3-1井渐新统下干柴沟组储集空间类型-《地球科学与环境学报》

文章信息/Info

Title:: Reservoir Space Types of Oligocene Xiaganchaigou Formation from Well S3-1 in Yingxi Area of Qaidam Basin, China

作者:: 黄成刚; 崔俊; 关新; 常海燕; 杨森; 惠媛媛; 吴梁宇; 吴丽荣; 1.中国石油天然气集团公司油藏描述重点实验室，甘肃兰州 730020； 2.中国石油勘探开发研究院西北分院，甘肃兰州 730020； 3.中国石油青海油田公司勘探开发研究院，甘肃敦煌 736202；4.西南石油大学地球科学与技术学院，四川成都 610500

Author(s):: HUANG Cheng-gang; CUI Jun; GUAN Xin; CHANG Hai-yan; YANG Sen; HUI Yuan-yuan; WU Liang-yu; WU Li-rong; 1. Key Laboratory of Reservoir Description of CNPC, Lanzhou 730020, Gansu, China; 2. Northwest Branch of Research Institute of Petroleum Exploration and Development, PetroChina, Lanzhou 730020, Gansu, China; 3. Research Institute of Exploration and Development, Qinghai Oilfield Company, PetroChina, Dunhuang 736202, Gansu, China; 4.School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, Sichuan, China

Keywords:: intercrystalline pore of dolomite; dissolution pore; Xiaganchaigou Formation; extra low porosity-extra low permeability; kinetics barrier; penecontemporaneous metasomatism; Yingxi oilfield; Qaidam Basin

摘要:: 近年来，柴达木盆地英西地区渐新统下干柴沟组的油气勘探取得了重大发现，但其主要储集空间类型一直是争论的焦点。基于对S3-1井的岩芯观察和系统的微观岩石学、结构学特征研究，总结出其主要储集空间类型为白云石晶间孔，而非溶蚀孔。其主要证据包括：①高沉积速率的暗色层段难以发生暴露溶蚀；②白云石为岩石最重要的矿物组分之一；③场发射扫描电镜下可见棱角状晶间孔广泛发育；④岩芯上观察到的孔洞系统在偏光显微镜下可见其均发育于裂缝之中，为盐类矿物结晶所致，非溶蚀而成；⑤“特低孔-特低渗”的物性特征；⑥较高的排驱压力、较小的连通孔喉半径以及极低的退汞效率；⑦荧光显微镜下表现为整体发光特征。这些发育极广的基质孔隙储油是英西地区亿吨级油田高产稳产的主控因素之一，研究结果对下一步勘探部署具有重要的指导意义。

Abstract:: In recent years, there is important discovery for oil and gas exploration of Oligocene Xiaganchaigou Formation in Yingxi area of Qaidam Basin. However, the main reservoir space types have been debated over. Based on core observation and systematically study of the micro petrological and structural characteristics of Well S3-1, the main reservoir space types were concluded. The results show that the main reservoir space types are intercrystalline pores of dolomite rather than dissolution pores. The main evidences include that the dark layers with high deposition rate are difficult for exposure and dissolution; dolomite is one of the most important minerals in rocks; under the field emission scanning electron microscope, the angular intercrystalline pores widely develop; because of the crystallization of salt minerals, not dissolution, the pores and holes observed in core are all in the fractures under the polarized microscope; the physical characteristic is “extra low porosity-extra low permeability”; the displacement pressure is high, the pore throat radius is small, and the efficiency of mercury withdrawal is very low; the characteristics under fluorescence microscopy is whole. Oil-bearing matrix porosity widely develop, so that it is one of the main control factors of large oilfield with high and stable yield in Yingxi area; the results have important guide for the further exploration.