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为科学评价鄂尔多斯盆地集义地区山西组砂岩储层微观孔隙结构特征及其对物性的影响,对定量表征储层孔隙结构的主要参数进行了分析,并探讨其与物性的关系。研究表明:研究区山西组主要发育石英砂岩,次为岩屑石英砂岩,平均孔隙度为6.79%,平均渗透率为0.71 m D,总体上物性较差。储层孔隙类型有残余粒间孔、粒间溶蚀孔、格架颗粒内溶孔、微孔隙、微裂缝等。根据砂岩毛细管压力曲线形态和参数特征,将其划分为低排驱压力—粗喉型、较低排驱压力—较粗喉道型、中排驱压力—中喉道型、高排驱压力—细喉道型等4种类型。砂岩孔隙度、渗透率均与排驱压力呈负相关关系,与孔喉半径均值呈正相关关系,与孔喉的分选系数呈正相关关系。低渗、特低渗储层中以偏细喉道为主,发育的较粗喉道能有效提高孔隙度和渗透率。
In order to scientifically evaluate the microscopic pore structure of sandstone reservoirs and its influence on physical properties in the Jiuxi Formation in the Jiadu area of the Ordos Basin, the main parameters for quantitatively characterizing the pore structure of the reservoirs were analyzed and their relations with physical properties were discussed. The results show that the Shanxi Formation of the study area is mainly composed of quartz sandstone, followed by lithic quartz sandstone with an average porosity of 6.79% and an average permeability of 0.71 m D, which is generally poor in physical properties. The types of reservoir pores are residual intergranular pores, intergranular dissolution pores, intragranular dissolved pores, micro-pores and micro-cracks. According to the capillary pressure curve shape and parameter characteristics of sandstone, it is divided into low-displacement pressure-coarse throat type, lower row pressure-coarse throat type, middle row pressure-middle throat type, high row pressure- Fine throat type 4 kinds of types. The porosity and permeability of sandstone are negatively correlated with the displacement pressure and positively correlated with the mean pore throat radius, and positively correlated with the pore-throat selection coefficient. The thinner throat in the low permeability and ultra-low permeability reservoirs is mainly developed and the thick throat can effectively improve the porosity and permeability.