Yang Bo, Wu Hongli, Peng Mou
National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing 102249, China.
College of Geosciences, China University of Petroleum, Beijing 102249, China.
ACS Omega. 2024 Apr 2;9(15):16976-16991. doi: 10.1021/acsomega.3c08258. eCollection 2024 Apr 16.
The paper focuses on deep oil and gas resources in the Bayingobi Formation of Guaizihu Sag in the Yin'e Basin. Previous studies overlooked the differences between the pores and throats, mainly focusing on pore analysis. This work aims to analyze the pore structure and petrophysical properties of the reservoir using various methods. The study utilized the constant velocity mercury intrusion method to quantify pores and throats separately. Scanning electron microscopy and casting thin section techniques characterize the pore and throat morphology. The analysis compares the pore structures in reservoirs with different petrophysical properties. Additionally, pore and throat types are classified based on fractal dimensions, and factors influencing their development are discussed. Results reveal feldspar lithic sandstone as the predominant rock type with a low compositional maturity. The sandstone reservoirs exhibit low porosity (10.23%) and ultralow permeability (0.99 mD). Primary reservoir pore spaces include intergranular pores, dissolution pores, and microfractures. Pore radius averages at 195.32 μm, while throat radius is 3.76 μm. Pore structures are categorized as micropore small-throat, small-pore small-throat, and large-pore coarse-throat types. The study area generally exhibits a high pore-to-throat ratio, impacting reservoir petrophysical properties significantly. Pore development is primarily influenced by early diagenesis, organic acid dissolution, and hydrocarbon filling. Weak compaction and cementation transformations provide a material and spatial basis for the subsequent dissolution. The presence of thick organic-rich mudstone above and below the reservoir contributes to organic acid dissolution and hydrocarbon filling.
本文聚焦于银额盆地拐子湖凹陷巴音戈壁组深层油气资源。以往研究忽视了孔隙与喉道之间的差异，主要侧重于孔隙分析。本研究旨在运用多种方法分析储层的孔隙结构和岩石物理性质。研究采用恒速压汞法分别对孔隙和喉道进行定量分析。利用扫描电子显微镜和铸体薄片技术表征孔隙和喉道形态。分析比较了不同岩石物理性质储层的孔隙结构。此外，基于分形维数对孔隙和喉道类型进行分类，并探讨了影响其发育的因素。结果表明，长石岩屑砂岩为主要岩石类型，成分成熟度较低。砂岩储层孔隙度低（10.23%），渗透率超低（0.99毫达西）。储层原生孔隙空间包括粒间孔隙、溶蚀孔隙和微裂缝。孔隙半径平均为195.32μm，喉道半径为3.76μm。孔隙结构分为微孔细喉型、小孔细喉型和大孔粗喉型。研究区总体孔隙喉道比高，对储层岩石物理性质影响显著。孔隙发育主要受早期成岩作用、有机酸溶蚀和烃类充注影响。弱压实和胶结作用转变为后续溶蚀提供了物质和空间基础。储层上下存在厚层富含有机质泥岩，有利于有机酸溶蚀和烃类充注。
