
科学技术与工程

中国技术经济学会
鄂尔多斯盆地东部太2上段储层特征及有利区预测
Reservoir Characteristics and Favorable Zone Prediction of the Upper Tai-2 Section in the Eastern Ordos Basin
为查明鄂尔多斯盆地东部太原组储层发育影响因素,利用铸体薄片、高压压汞、恒速压汞等实验方法开展了太2上段储层孔隙结构特征的研究。结果表明,太2上段储层平均孔隙度为7.84%、平均渗透率为0.396 mD,以特低孔-超低渗为主,孔隙结构复杂,非均质性强。储层发育粒内溶孔、粒间溶孔、晶间孔、岩屑溶孔等;根据各区域孔隙发育频率、孔隙度与渗透率,将孔隙组合分为3类:粒内溶孔、粒内溶孔+晶间孔、粒内溶孔+粒间溶孔,高压压汞和恒速压汞的实验方法能够较好地表征3类孔隙组合的储层特征,其中粒内溶孔+晶间孔的组合是良好的储层孔隙类型。根据沉积分异和孔隙分异规律,在实验结果的基础上建立优质储层评价标准,将太2上段储层由好到差分为Ⅰ、Ⅱ、Ⅲ类,并对优质储层有利区做出预测。
The influencing factors on the reservoir development of Upper Taiyuan Formation in the eastern Ordos Basin were investigated. Experimental methods such as casting thin sections, high-pressure mercury intrusion, and constant-rate mercury intrusion were employed to examine the pore structure characteristics of Upper Taiyuan Formation, Tai 2 Member. Results show that the average porosity of Tai 2 Member reservoir is 7.84%, with an average permeability of 0.396 mD, primarily characterized by ultra-low porosity and permeability. The pore structure is complex, with strong heterogeneity. Various types of pores were developed in the reservoir, including intragranular dissolution pores, intergranular dissolution pores, intercrystalline pores, and rock fragment dissolution pores. Based on the frequency of pore development, porosity, and permeability in each region, the pore combinations are classified into three types: intragranular dissolution pores, intragranular dissolution pores combined with intercrystalline pores, and intragranular dissolution pores combined with intergranular dissolution pores. The experimental methods of high-pressure mercury intrusion and constant-rate mercury intrusion could effectively characterize the reservoir characteristics of these three types of pore combinations, among which the combination of intragranular dissolution pores and intercrystalline pores represents a favorable reservoir pore type. Based on the laws of sedimentary differentiation and pore differentiation, a set of criteria for evaluating high-quality reservoirs is established on the basis of experimental results. Upper Taiyuan Formation reservoir was classified into Class Ⅰ, Ⅱ, and Ⅲ from good to poor, and predictions were made for favorable areas of high-quality reservoirs.
Ordos Basin / Upper Tai-2 / reservoir characterization / pore structure
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