莫西庄油田三工河组二段砂岩储集层物性下限

莫西庄油田三工河组二段储集层总体呈现低孔低渗、非均质性强的特点,基于岩心常规分析、压汞、试油等资料,对比常用的有效储集层物性下限确定方法在研究区的应用效果,确定了三工河组二段储集层物性下限,并对影响储集层物性下限的主要因素进行了分析。研究结果表明,莫西庄油田三工河组二段储集层岩性主要为三角洲前缘沉积的细—中砂岩,储集空间类型以原生粒间孔为主,储集层物性下限求取方法中启动压力梯度法、分布函数曲线法和含油产状法在研究区更具适用性,综合确定孔隙度下限为10.1%,渗透率下限为1.15 mD;沉积相和成岩作用是影响研究区储集层物性下限的主控因素,水下分流河道微相强溶蚀弱压实弱胶结型储集层的物性下限最低,此外,原油性质、埋藏深度等是影响储集层物性下限的次要因素。

Lower Limits of Physical Properties of Sandstone Reservoirs in the Second Member of Sangonghe Formation in Moxizhuang Oilfield

The second member of Sangonghe formation in Moxizhuang oilfield presents the characteristics of low porosity, low permeability and strong heterogeneity. Based on the data of conventional core analysis, mercury injection and formation test, the paper compares the application effects of commonly-used methods to determine the lower limits of physical properties of effective reservoirs in the study area, determines the lower limits of reservoir physical properties in the second member of Sangonghe formation, and analyzes the main factors influencing the lower limits of reservoir physical properties. The results show that the second member of Sangonghe formation in Moxizhuang oilfield is mainly composed of medium-fine sandstone deposited in delta front, the reservoir space of the formation is dominated by primary intergranular pores, and the methods of starting pressure gradient, the distribution function curve and oil-bearing occurrence are very practical for determining the lower limits of reservoir physical properties in the study area, and the lower limits of reservoir porosity and permeability are determined as 10.1% and 1.15 mD, respectively. Sedimentary facies and diagenesis are the main factors affecting the lower limits of reservoir physical properties. Strong dissolution, weak compaction and weak cementation reservoirs of underwater distributary channel microfacies have the lowest limits of physical properties. In addition, crude oil properties and reservoir burial depth are the minor factors affecting the lower limits of reservoir physical properties.