大庆榆树林油田是重要的致密油聚集区,综合利用高压压汞技术、恒速压汞技术及低温氮气吸附技术等实验手段,建立了致密油储层孔喉物性评价方法,系统开展了研究区不同区块储层的微观孔隙结构定量表征研究,并对储层做出综合评价。研究表明:研究区不同层位储层样品的孔喉配套发育程度与渗透率相关性较好,当岩心渗透率较高时孔喉发育程度较高,有利于原油产出;岩心渗透率降低时储层物性和孔喉连通性恶化,小孔隙占比增加,平均孔隙半径减小,孔隙分选性降低,对原油产出不利。按渗透率可将研究区储层划分为0.5~1.0 mD、0.1~0.5 mD和 <0.1 mD 三个级别,其平均喉道半径分别为0.40、0.28和0.14 μm,渗透率<0.1 mD储层的最大喉道半径和平均喉道半径整体上均较小,开发难度大。研究区FII、FIII和YI层位储层的最大喉道半径和平均喉道半径整体上均较小,其平均喉道半径分别为0.28、0.11和0.24 μm,主流喉道半径和平均喉道半径整体上随渗透率增大而增大。岩样比表面和渗透率呈现较好的负相关关系,而与孔隙度呈现一定的负相关关系,FII层位的比表面明显高于其他三层,对应储层岩石对流体的吸附能力更强,开发难度更大。研究成果可为致密油储层孔隙结构表征及高效开发提供科学依据。

 The Daqing Yushulin Oilfield is an important tight oil accumulation area. A method for evaluating the pore throat properties of tight oil reservoirs was established through the comprehensive utilization of high-pressure mercury injection technology, constant rate mercury injection technology, and low-temperature nitrogen adsorption technology. A systematic study was conducted on the quantitative characterization of the micropore structure of reservoirs in different blocks of the study area, and a comprehensive evaluation of the reservoirs was carried out. The results show that there is a good correlation between the degree of pore throat development and permeability in reservoir samples from different layers in the study area. When the core permeability is higher, the degree of pore throat development is greater, which is conducive to the production of crude oil. On the contrary, when the core permeability decreases, the physical properties of the reservoir and the connectivity of the pore throat deteriorate, the proportion of small pores increases, the average pore radius decreases, and the pore sorting worsens, which is unfavorable for the production of crude oil. According to permeability, the reservoirs in the study area can be classified into three levels:0.5~1.0 mD, 0.1~0.5 mD, and less than 0.1 mD, with average throat radius of 0.40 μm,0.28 μm, and 0.14 μm, respectively. The maximum throat radius and average throat radius of reservoirs with less than 0.1 mD are generally small, making development difficult. The maximum and average throat radii of reservoirs in blocks FII, FIII, and YI in the study area are generally small, with an average throat radius of 0.28 μm,0.11 μm, and 0.24 μm respectively. The mainstream throat radius and average throat radius generally increase with increasing permeability. There is a strong negative correlation between samples- specific surface area and permeability, while there is a certain negative correlation with porosity. The specific surface of the FII layer is significantly higher than that of the other three layers, corresponding to a stronger adsorption capacity of the reservoir rock for fluids and greater development difficulty. The research results can provide scientific basis for pore structure characterization and efficient development of tight oil reservoirs.