利用岩石物理相“甜点”筛选特低渗透储层含油有利区

陕北斜坡中部特低渗透储层受沉积环境、成岩作用、构造等因素的影响,储层具有宏观物性和微观孔隙类型多样、储集性能和渗流结构差异较大、流动层带复杂等特点,利用岩石物理相流动单元"甜点"筛选特低渗储层含油有利区。选用反映多孔介质地质特征的流动层带指标、储能参数、成岩综合系数、单渗砂层厚度、油层有效厚度、砂地比、渗透率、孔隙度、泥质含量及夹层的分布频率和分布密度等参数,建立了岩石物理相"甜点"综合评价指标体系。通过灰色理论集成,综合上述储层渗流、储集特点及含油气与非均质的多种信息,利用Ⅰ类、Ⅱ类岩石物理相"甜点"圈定出含油有利区位置及分布范围,集中地反映出该区特低渗透储层含油有利区形成的地质特点。

Determination of favorable oil-bearing areas with extra low-permeability reservoir by dessert of petro-physical facies

The extra low-permeability reservoirs in the middle part of Shaanbei slope are affected by many factors, such as sedimentary environment, diagenesis and structure. Both macroscopic physical property and micropore types of these reservoirs have strong heterogeneity， so the quality and percolation structure of the reservoir have a large difference. The flow zones are complex in the extra low-permeability reservoirs of the middle part of Shaanbei slope. A determination method was presented for favorable oil-bearing areas in the extra low-permeability reservoir using flow units of petro physical facies. A comprehensive evaluation system of “dessert” of petro-physical facies was developed using various parameters for describing geologic features of porous medium, including flow zone indicator, energy storage parameters, diagenetic synthetical coefficient, thickness of single-permeability sandstone, effective thickness of oil layers, the ratio of sand body to formation thickness, permeability, porosity, shale content, and distribution frequency and density of inter-players. Above various parameters including permeability and storage capability, oil and gas bearing features and heterogeneity of reservoirs were integrated and synthesized by gray theory. The locations and distribution of favorable oil bearing area were effectively determined by using “dessert” of Type Ⅰ and Type Ⅱ petro-physical facies. The results could fully reflect geological features of the favorable oil-bearing areas in the extra low-permeability reservoirs.