Oil Enrichment Area Optimization Of Chang 7 Reservoir In Heshui Area,Ordos Basin

This paper's object of study is Chang7 oil formation of Heshui area in Ordos basin,using a variety of methods such as sequence stratigraphy,theories of sedimentary and reservoir geology as the main theoretical guidance,based on core observation,logging data and other test analysis,the stratum sedimentary microfaces reservoir characteristics and regularities distribution of oil enrichment area is researched systematically,and obtains following conclusions.The average stratum thickness of Chang7 oil formation in Ordos basin is about 34 meters,the tendency of sedimentary stratum is west-southwest.There are three types of microfaces developed in study area.They are turbidity channel,between turbidity channel and front of turbidity channel microfaces.The sand body is controlled by sedimentary microfacies,the direction of sand body distribution is northeast.The most part of Chang7 reservoirs have reached mid-A diagenetic periods,the other part have reached B diagenetic period after experienced diagenetic process which mainly contains process of compaction,cementation,metasomasision and dissolution.Chang7 reservoirs are divided into four diagenetic faces on the basis of diagenetic characteristics and parameter,permeability and porosity of sand stone,characteristics of pore throat,parameter of pore structure,the best diagenetic phase of reservoir is clay membrance add intergranular pore diagenetic phase,the worst diagenetic phase is dense phase,between this two types of diagenetic phase are dissolved pore of felbspar and illite cementation diagenetic phase.Using the methods of constant-speed mercury injection and conventional mercury injection to do deep research on characteristics of mico-pore throat and reservoir physical property.The results of experiment shows that,the permeability and porosity of Chang71 is better than Chang72 and Chang73,The permeability of the Chang7 reservoir is mainly controlled by the throat.On the basis of the above analysis,in combination with the actual situation of study area,the reservoir in the study area are divided into four classes.The first and second class of reservoir are better than the third and fourth class of reservoir.The worst reservoir is the fourth class of reservoir.The factors of hydrocarbon accumulation in Heshui Area are studied on the basis of reservoir profile analysis and a large number of previous research results,the results shows that the type of Chang 7 reservoir of Heshui area is non-structural reservoir,is also a typical dense reservoir.The process of reservoir forming is oil and gas gather into reservoirs first,and then it becomes dense after a series of physical and chemical changes.The regular of oil enrichment is mainly controlled by reservoir.Among the three reservoir of the Chang7,the most oil abundant formation of Chang7 is Chang71,24 oil rich areas are obtained in this formation,the second oil abundant formation is Chang72,18 oil rich areas are obtained in this formation.Because of poor reservoir development,Chang 73 oil formation has a small number of reservoirs.The reservoir is mainly developed in the reservoir of ?+?.