The Reservoir Evaluation And Geological Modeling Of Chang6 Oil Set Of Yanchang Formation In Wangjie Exploration Area Of Ordos Basin

Wangjie exploration area of Ansai oil field whose main oil-bearing formationslies are Chang2 and Chang6 formations lies in the east-central of Northern Shanbei Slope,Ordos Basin,and it is in early development phase now.In this paper, a method of detailed division of the microfacies was used to study formation ,depositional microfacies ,diagenesis , physical property and reservoir heterogeneity of chang6 formation by multi-disciplinary knowledge.The author evaluated chang6 formation comprehensively and established a physical property parameter model of it ,all of which provided for the subsequent waterflooding extraction of a reliable theoretical basis.Based on index bed and sedimentary cycle the chang6 formation was divided into four sub-groups 61,62,63 and 64.Because 61 is the main producing bed ,and it was then be subdivide into three small formations 61-1,61-2,61-3.Chang61 formation belongs to an environment of delta frontal subfacies.Its primary types of the reservoirs include underwater distributary channel,Underwater distributary channel lateral margin,distributary interchannel and its major reservoir is sand bodies of subaquatic distributary channels. The reservoir whose rock types consists of abundant celadon to gray fine-grained feldspathic sandstones, and a small number of middle-fine grained sandstone has a low compositional maturity and high texture maturity. The diagenesiss mainly includes compaction, pressure solution and dissolution.The reservoir space are mainly remainder intergranular, the secondary zeolitic dissolved pore, intragranular pore, fracture pore and a few moldic pore. The pore composition is mainly residual intergranular pores-dissolution pores, and most of which are thin throats-tiny throats ;The reservoir has a bulk porosity value of 9.68% and a mean permeability value of 0.64×10-3 m2 from which we can see the reservoir belongs to a low porosity and super-low permeability;It is found that the oil and gas exist unbalanced distribution in both vertical plane and horizontal plane by the research of reservoir heterogeneity;The main part of Chang6 reservoir belongs to the super-low permeability reservoir through the comprehensive evaluation to Chang6 reservoir.Constructed the corresponding geological model as structure model ,sand body model and attribute model with Petrel reservoir modeling software. It distinctly shows the heterogeneity of every small reservoir, and pointed the direction for the follow-up exploration and development.