华庆地区长7₁储层特征研究

Research on the Characteristics of Chang 7₁ Reservoir in Huaqing Area

鄂尔多斯盆地华庆地区长71为非常规致密储层,蕴含着丰富的页岩油资源,但其储层特征目前还缺乏更深层次的研究,制约了页岩油勘探以及开采。本文综合运用岩心直观观察、高分辨率扫描电子显微镜(SEM)分析、压汞法孔隙结构测试以及铸体薄片技术等多种实验方法对华庆地区长71储层的微观特征做了进一步探究。研究结果表明:华庆地区长71储层主要由黑色页岩和砂岩构成,同时含有少量暗色泥岩,砂岩的种类包含岩屑长石砂岩、长石岩屑砂岩以及岩屑砂岩;该储层的孔隙以残余粒间孔和溶蚀孔为主,并且少量存在微裂缝和晶间孔,平均面孔率为1.01%;华庆地区长71储层属于特低孔–超低渗储层,孔隙度在6%~10%范围内的频率较高,平均值7.55%,渗透率在0.03 × 10−3 μm2~0.15 × 10−3 μm2范围的频率较高,平均值0.095 × 10−3 μm2。根据储层分类评价标准将71储层分为4类,I类和II类储层含油性好,储量较高,试油效果较好,综合评价为优良储层。The Chang 71 reservoir in the Huaqing area of the Ordos Basin is an unconventional tight reservoir that holds abundant shale oil resources. However, the lack of deeper research on its reservoir characteristics has hindered the exploration and production of shale oil. This paper comprehensively utilizes various experimental methods such as direct core observation, high-resolution scanning electron microscopy (SEM) analysis, mercury intrusion porosimetry for pore structure testing, and cast thin section technology to conduct an in-depth study of the microscopic characteristics of the Chang 71 reservoir in the Huaqing area. The research results indicate that the primary rock types in the Chang 71 reservoir of the Huaqing area are black shale and sandstone, with a small amount of dark mudstone. The sandstone types include lithic feldspathic sandstone, feldspathic litharenite, and lithic sandstone. The pores are primarily residual interparticle pores and dissolution pores, with a few microfractures and intercrystalline pores developed, and the average face porosity is 1.01%. The Chang 71 reservoir in the Huaqing area belongs to the ultra-low porosity and ultra-low permeability category, with porosity frequently ranging from 6% to 10% (average of 7.55%) and permeability frequently ranging from 0.03 × 10−3 μm2 to 0.15 × 10−3 μm2 (average of 0.095 × 10−3 μm2. Based on the reservoir classification and evaluation criteria, the Chang 71 reservoir is divided into four categories. Reservoirs of Category I and II exhibit good oil-bearing properties, high reserves, and satisfactory oil testing results, leading to an overall evaluation as excellent reservoirs.