The Reservoir Evaluation Of The Chang-6Member Of The Yanchang Formation In Sansheng Rejion, Jingbian Oil Field

In order to provide the scientific prediction of the geology on expanding exploration and forecasting oil favourable object, it is necessary to research meticulously relationship between the reservoir characteristic and the oil-gas enrichment of Sansheng region in Jingbian oilfield. In this paper, using the related theory of petroleum geology as a guide, reservoir characteristic of sedimentary micro-facies, petrology, diagenesis, physical property and heterogeneity of Chang-6reservoir in Sansheng region are studied, classificated and evaluated, then the relations between reservoir and the oil-gas was conclued.Sansheng area of Jingbian oilfield is located in the south of Jingbian county of Shaanxi province.It’s tectonic location is the Shanbei slope of the eastern part of the Ordos basin.The Chang-6member of the Yanchang formation is the main bed producing oil. According to the characters of lithology,electricity and oiliness,the Chang-6member of the Yanchang formation is subdivided into Chang-61,Chang-62,Chang-63and Chang-64types, and established the unified stratigraphic framework on the basis of contrasting the stratigraphic.Based on the analysis of the facies signs,such as sedimentary background,the distribution pattern of the sandstone in plane.the facies marks and logging curve.the analysisi of the facies shows that the Chang-6member of the Yanchang formation of Sansheng is a delta plain sedimentary system and the development of smaller of other micro-phase,such as natural levee, crevasse splay, swamp, oil and gas accumulation zone is the better reservoir properties of channel sand. Corrosion improved the reservoir properties, provide a good reservoir space, carbonate cements, and other reservoir properties deteriorate, blocking the transport of oil and gas.The Core observation, rock section, analysis determination of large amounts of data have shown that the mainly rock type of Chang-6reservoir of the Yanchang formation is arcose, the mainly pore type is protogene intergranular pore.The Lower limit of average porosity is8%,average permeability of the lower limit is0.15<10-3μm2.The reservoir sandstones has been reached in A of the system diagenetic stage. The Chang6reservoir has poor properties, a low porosity-extra low permeability reservoirs, has strong aeolotropism. According to the standard of classification,the reservoir will be divided into three types, types Ⅰ in the reservoir (better reservoir) is mainly distributed in the distributary channel sand, the reservoir of classll (good reservoir) and class III (poor reservoir) in the distributary channels flank and distributary interchannel.