Quantitative Characterization Of Tight Oil Reservoir Heterogeneity By Well

Ordos basin is rich in tight oil resources,the reservoir scale is large,and the underground reservoir has strong heterogeneity.The yanchang 7 reservoir developed in the deep-semi-deep lake is a typical tight reservoir.The jiyuan oilfiled in the study area is located in the southwest of the ordos basin.Due to the poor reservoir physical properties and complex void structure,the development and utilization of tight oil reservoirs are severely restricted.Under the theoretical guidance of petroleum sedimentology,well logging geology and reservoir geology and reservoir geology,divided the chang7 oil reservoir group into three small formations:chang7₁,chang7₂ and chang7₃.With logging data,core data and production data of sedimentary microfacies,such as understanding of sedimentary facies belt distribution characteristics of sedimentary microfacies in the study area are mainly delta front subfacies,mainly including underwater distributary channel micofacies,debouch bar microfacies,distributary bay between mud microfacies and former delta and lacustrine mud,etc.Using advanced technologies such as double beam electron microscopy casting thin section and scanning electron microscopy,the reservoir physical properties were systematically analyzed and characterized by permeability and porosity.The reservoir heterogeneity is controlled by sedimentary facies,and the basic factor affecting the reservoir heterogeneity,sedimentary facies,rock type and stratigraphic structure are analyzed by using facies markers,logging facies,single well facies and profile structure.Sedimentation,diagenesis and structure used is also causing factors of reservoir heterogeneity,the diagenesis in the study area are mainly compaction and pressure solution,cementation and dissolution,compaction and shouted apply make the reservoir density,physical decline,dissolution change of reservoir space,cementation can reduce void volume and deteriorate reservoir property.Based on these functions,the intersection graph of GR DEN AC CNL and Rt of five conventional diagenetic facies,so as to further characterize the reservoir's plane heterogeneity,inter-layer heterogeneity and intra-layer heterogeneity.The lithofacies model was established to display the sand body and structure and sedimentary facies characteristics directly.thereby enhancing the reservoir.So as to realize the intuitive display of tight oil reservoir heterogeneity and provide geological basis for oilfield development.