Li Hongtao, Liu Tao, Liu Qingbin
Petroleum exploration and Development Research Institute, Sinopec, Beijing, China.
PLoS One. 2025 Sep 8;20(9):e0329942. doi: 10.1371/journal.pone.0329942. eCollection 2025.
The Ordos Basin's Hangjinqi Shiligahan west zone Xiashihezi Formation 1 Member gas reservoir exhibits significant exploration and development potential. However, its sedimentation and reservoir characteristics are poorly understood. To address this, geological, seismic, macroscopic, and microscopic methods are combined. The available data includes core observation, thin sections, physical property analysis, mercury injection curve interpretation, seismic attribute predictions, and so on. The results show that the target stratum lithology and sedimentary structure are complex and diverse. They are dominated by gravelly coarse sandstone facies with strong hydrodynamic conditions, intercalated with thin mudstone and siltstone. The vertical meter-scale cycle sedimentation characteristics are distinct, representing a typical shallow braided river deposition. Through the mutual calibration and verification of lithology, logging, and seismic facies, the braided channel and its internal microfacies boundaries were accurately delineated. The reservoir primarily consists of gravel-bearing coarse sandstone, featuring intergranular and intragranular dissolved pores as the primary types of reservoir space. The pore types are predominantly mesopores and small pores, with pore-throat combinations favoring mesopores and medium throats, as well as medium to small pores and fine throats. The reservoirs average porosity and permibility are 7.6% and 0.53mD, respectively. This defines a typical reservoir with low to ultra-low porosity and low to ultra-low permeability. The sedimentary microfacies and their associated hydrodynamic conditions are crucial for the development of the reservoir in the Xiashihezi Formation 1 Member. This leads to variations in reservoir properties and pore structures. Thus, the reservoirs are predominantly located in the channel bar microfacies, clearly demonstrating characteristics of facies-controlled reservoir development.
鄂尔多斯盆地杭锦旗什里嘎汗西部区下石盒子组一段气藏具有显著的勘探开发潜力。然而，其沉积和储层特征尚不清楚。为解决这一问题，综合运用了地质、地震、宏观和微观方法。现有数据包括岩心观察、薄片分析、物性分析、压汞曲线解释、地震属性预测等。结果表明，目的层岩性和沉积构造复杂多样。以水动力条件较强的含砾粗砂岩相为主，夹有薄层泥岩和粉砂岩。垂向上米级旋回沉积特征明显，为典型的浅水辫状河沉积。通过岩性、测井和地震相的相互标定和验证，准确圈定了辫状河道及其内部微相边界。储层主要由含砾粗砂岩组成，储集空间主要为粒间溶孔和粒内溶孔。孔隙类型以中孔和小孔为主，孔喉组合以中孔和中喉、中小孔和细喉为主。储层平均孔隙度和渗透率分别为7.6%和0.53mD。这是一个典型的低孔超低孔、低渗超低渗储层。沉积微相及其相关的水动力条件对下石盒子组一段储层的发育至关重要。这导致了储层性质和孔隙结构的变化。因此，储层主要位于河道砂坝微相，明显表现出相控储层发育的特征。
