塔里木盆地库车坳陷英买力地区白垩系巴什基奇克组中深层砂岩储层孔隙保存机制

Preservation mechanism of pores in middle and deep sandstone reservoirs of Cretaceous Bashijiqike Formation in Yingmaili area, Kuqa Depression, Tarim Basin

张亮 朱毅秀 周露 秦凯旋 蒋俊 熊荣坤 李泽州

ZHANG Liang ZHU Yixiu ZHOU Lu QIN Kaixuan JIANG Jun XIONG Rongkun LI Zezhou

1. 中国石油 塔里木油田分公司 勘探开发研究院, 新疆 库尔勒 841000; 2. 中国石油 超深层复杂油气藏勘探开发技术研发中心, 新疆 库尔勒 841000; 3. 新疆维吾尔自治区超深层复杂油气藏勘探开发工程研究中心, 新疆 库尔勒 841000; 4. 中国石油大学(北京) 地球科学学院, 北京 102249; 5. 中国石油大学(北京) 油气资源与探测国家重点实验室, 北京 102249

1. Research Institute of Exploration and Development, Tarim Oilfield Company, PetroChina, Korla, Xinjiang 841000, China; 2. R & D Center for Ultra-Deep Complex Reservoir Exploration and Development, CNPC, Korla, Xinjiang 841000, China; 3. Engineering Research Center for Ultra-Deep Complex Reservoir Exploration and Development, Xinjiang Uygur Autonomous Region, Korla, Xinjiang 841000, China; 4. College of Geosciences, China University of Petroleum (Beijing), Beijing 102249, China; 5. State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing), Beijing 102249, China

塔里木盆地库车坳陷南部斜坡带英买力地区白垩系巴什基奇克组砂岩储层物性好，油气勘探潜力大，但其非均质性强、油气分布规律不明。综合利用岩心观察、系列薄片(普通、铸体、阴极发光及包裹体)、扫描电镜、物性测试和X射线衍射等分析测试资料和成岩过程重建与物性恢复技术，分析英买力地区中深层巴什基奇克组砂岩储层的岩性与物性，探寻其孔隙特征与保存机制，划分储层类型和明确有利储层分布规律及控制因素。该砂岩主要为长石岩屑砂岩和岩屑长石砂岩，杂基含量较低，其成分和结构成熟度均中等；储层孔隙类型主要为残余原生孔隙，其次为次生孔隙，主要为粒间溶孔和粒内溶孔，为中高孔—中高渗储层。巴什基奇克组中深层砂岩原生孔隙得以保存主要在于其形成的沉积环境与经历的成岩和成储演化：首先砂岩形成于高水动力的辫状河三角洲前缘水下分流河道微相，不断叠置的河道形成了厚度较大且分布稳定的水道复合砂体，强水动力使得砂岩碎屑颗粒含量高、分选较好，为原生孔隙形成提供了物质基础；其次早期长期浅埋和后期快速深埋的埋藏演化方式使砂岩经历了较弱的压实作用改造，同时晚期深层超压作用大大增强了砂体抗压实能力，残余原生孔隙得以保存；最后坳陷不断降低的古地温梯度使得残余原生孔隙得以有效保存。

The sandstone reservoirs of the Cretaceous Bashijiqike Formation in the Yingmaili area on the southern slope of the Kuqa Depression within the Tarim Basin demonstrate favorable physical properties and considerable potential for oil and gas exploration. However, they are characterized by strong heterogeneity and unclear patterns of oil and gas distribution. In this study, the lithology and physical properties of the middle and deep reservoirs of the Bashijiqike Formation in the Yingmaili area were analyzed using core observation, a series of thin section analyses(standard, casting, cathodoluminescence, and inclusion thin sections), scanning electron microscopy(SEM), physical property testing, X-ray diffraction, and diagenesis reconstruction and physical property recovery techniques. It aims to explore the pore characteristics and preservation mechanisms, classify reservoir types, and clarify the distribution patterns and controlling factors of favorable reservoirs.The results show that the sandstone is mainly composed of feldspathic lithic sandstone and lithic feldspathic sandstone with low matrix content and medium maturity in both composition and structure. The primary pore type of the reservoir is residual primary pores, followed by secondary pores, including intergranular and intragranular dissolution pores, classifying the reservoir as a medium-to-high porosity and permeability type. The preservation of the primary pores in the middle and deep sandstones of the Bashijiqike Formation was mainly attributed to the depositional environment and subsequent diagenetic and reservoir evolution. The sandstone was initially formed in the microfacies of distributary channels at the front edge of a braided river delta with high hydrodynamics. The constantly overlapping channels formed thick and stable composite sand bodies. The strong hydrodynamics in the area led to high concentration and good sorting of sandstone clastic particles, providing the material basis for the formation of primary pores. The burial evolution process involved early long-term shallow burial and late-stage rapid deep burial, resulting in weak compaction transformation of the sandstone. Meanwhile, late-stage deep overpressure greatly enhanced the sand body’s resistance to compaction, allowing for the preservation of residual primary pores. The continuously decreasing paleogeothermal gradient in the depression further contributed to the effective preservation of residual primary pores.

中国石油攻关性应用性科技专项“超深层碎屑岩油气规模增储上产与勘探开发技术研究”(2023ZZ14YJ02)资助。

https://doi.org/10.11781/sysydz2024051075