The Researching Of Characteristic Of Chang 6 Reservoir In Jianyucha Oilfield Of Zichang Area

Jianyucha oil field is located in Shanbei slope of the south Ordos Basin.The Chang-6 oil-bearing bed is the main bed producing oil.According to the characters of lithology,electricity and oiliness,the Chang-6 oil-beating bed is subdivided into Chang-6₁,Chang-6₂ and Chang-6₃,and contrast the stratigraphic.According to the analysis of the facies signs,such as rock kinds with the features, sedimentary structure,fossils,logging facies and other criteria in the study area,the analysis of the facies shows that the Chang-6 oil-beating beds is a delta plain sedimentary system,On the basis of the study area sedimentary background,then combined with the geology character and logging facies,we analysis the distribution pattern of sandstone thickness and sandstone percent in plane comprehensively,and further it is devided into two sedimentary microfacies:distributary channel and floodplain swamp.The research on granularity,flakes,properties and so on show that the reservoir sandstone in the study area is fine-graded feldspar sandstones and the reservoir sandstone has reached the late diagenesis A period.The porosity is mainly the kind of intergranular pore,And the composition of pore throat is the small pore with Micro-throat type.In generally speaking,the reservoir is low porosity-extra-special low permeability～extra low porosity-ultra-low-permeability reservoir.On this basis,we think that the reservoir is main belongs toâ…£type,that is worse reservoir.Analyzing the controlling factors to reservoir,sedimentary microfacies is the main factors of controlling and affecting the distribution of reservoir in study area.The research on unhomogeneity of reservoir also shows that the unhomogenenity is strong.The result of the analysis on natures of oil,water and so on show that the oil of Chang-6 oil-bearing beds in the study area belongs to conventional oil which terrestrial facies with low density,medium viscosity,medium freezing point and low sulfur content.And the kind of formation water in the study area belongs to calcium chloride(CaCl₂).The total saltiness of formation water is comparatively high.The sandstones of reservoir act as water-wet.The kind of trap is lithologic trap which belongs to normal temperature and low pressure system with the elastic-soluble gas driving oil.The research also obtains enrichment regulation of the Chang-6 reservoirs.It shows that the study reservoir is controlled by delta plain distributary river where is considered as the most important deposit areas.The fine regional cap formation also supply the good barrier conditions.According to the kinds and distribution on space of the trap,and combined with the reviewing studies,the research concludes that there are two accumulation models,one is the sandstone lens reservoir,the other is sandstone updip wedge-out reservoir.