利用单渗砂层能量厚度研究有利沉积微相及其含油有利区的方法

Study on Favorable Sedimentary Microfacies and Favorable Oil-bearing Areas by Energy Thickness of Single Permeability Sand Bed

针对鄂尔多斯盆地陕北斜坡中部特低渗透储层识别主体骨架砂体微相带及筛选含油有利区工作,提出利用单渗砂层能量厚度控制划分最为有利的沉积微相带。利用多种测井响应提取单渗砂层沉积能量及其能量厚度信息,使其曲线幅度、厚度、形状、接触关系、次级形态等特征和数据大小能够集中反映相对高渗的单渗砂层最大沉积能量及厚度变化,确认出三角洲前缘水下分流河道微相及其河道叠置型河口坝微相骨架砂体的发育、规模及分布范围,有效地克服了层段中几个成因相近薄砂层或砂泥互层中砂层累加厚度识别和划分主体骨架砂体微相带的失误。通过该区目的层段自然电位、自然伽马、密度、中子、声波、电阻率测井曲线和岩性、物性及其能量厚度统计,建立起单渗砂层能量厚度下限标准及夹层扣除标准,在该区长4+511特低渗透储层中提取单渗砂层及其沉积能量信息,控制划分出有利沉积微相带及其骨架砂体分布,预测和筛选出不同类型相对高渗高产含油有利区,它们不同程度勾画出河道主体带油藏与南西部华池油藏连片延伸趋势、形态和特征,为该区特低渗透油田增储上产提供有利目标和重点层位及井区。

Aiming at identifying microfacies belt of Main Framework Sandbody and filtering the relative high permeability, high production favorable oil-bearing areas with extra-low permeability reservoir in the middle of Shanbei Slope of Ordos Basin, it was presented that using Energy Thickness of Single Permeability Sand Bed controlled and classified optimum sedimentary microfacies belt. Information of depositional energy and its thickness in Single Permeability Sand Bed is extracted by multi logging response , in other words, maximum depositional energy and its thickness variation of Single Permeability Sand Bed with the＇relative high permeability could be reflected by the latitude, thickness, figure, contact relationship and secondary form of logging curve and data size, by which it is confirmed that development, the scale and distribution of the Framework Sandbody of the underwater distributary channel microfacies and channel overlying debouch bar microfacies of delta front subfacies, meanwhile, the mistakes are effectively overcome which resulted in failing to successful identifying accumulate thickness and microfacies belt of Main Framework Sandbody of thin sand and sandstone and mudstone inter-bedding of several similar origin in the studied reservoirs. Throuth the statistics of natural-potential, natural gamma, density, neutron, interval transit time, resistivity log curve, and lithology, physical property and Energy Thickness in the studied layers, the cutoffs criterion of Energy Thickness of Single Permeability Sand Bed and the elimination criterion of interlayer were proposed, and the information of Single Permeability Sand Bed and its Energy Thickness was extracted in extra-low permeability reservoirs Chang 4 ＋ 511 in the studied areas, by which classification of favorable sedimentary microfacies belt and distribution of its framework sandbody could be controlled, and the relative high permeability, high production favorable oil-bearing areas which are different types were predicated and filtered, which sketching the extend tendency, form, and feature between the river channel body areas and Hua Chi oil field in the southwest. The results can offer favorable target , important positions and weil field for enlarging reservoirs and raising yield in the extra-low permeability reservoirs.