Researches About Microscopic Features And Comprehensive Evaluation Of Chang 6 Reservoir Of Tiebiancheng Area In Jiyuan Oilfield

The Chang 6 reservoir in Tiebiancheng area is a typical low-permeability sandstone reservoir.The pore throat is complex and diverse,and the degree of connectivity is low.The seepage law of oil and water is different from that of conventional reservoirs.The contradiction between production and construction during development is seriously highlighted.Based on this,this paper studies the basic geological characteristics of reservoirs in the macroscopic aspect,and uses microscopic aspects to explore the microscopic pore structure and seepage mechanism of reservoirs using various advanced experimental techniques to achieve the qualitative-quantitative characterization of micro geological features.Based on the classification of reservoirs by various advanced microscopic experimental techniques,with reference to the division results of the reservoir flow units in the study area,the comprehensive assessment parameters of the Chang 6 reservoirs can be finally obtained,and then the reservoirs can be comprehensively evaluated and divided.Get the following main understanding:(1)The Chang 6 reservoir belongs to the sedimentary subfacies of the delta front.The developed sedimentary microfacies are underwater distributary channel,Hekou dam,and inter-distributary bay.The structure is relatively stable and monotonous,and the local area develops an almost east-west wide nose-like uplift structure.(2)The type of rock is mainly fine-grained feldspar sandstone,and the detrital components are mainly feldspar.The overall structural maturity and compositional maturity are not high.The reservoir properties are poor,the average porosity is 10.61%,and the average permeability is 0.46×10-3?m2.The diagenesis is strong,with major development of compaction(dissolution),cementation,dissolution and metasomatism.The types of pores developed in the Chang 6 reservoir include intergranular pores,feldspar dissolved pores,rock debris dissolved pores,intercrystalline pores,and micro-fractures,and the flake-shaped and curved flume throats are highly developed.(3)Chang 6 reservoirs have complex pore throat characteristics and strong reservoir heterogeneity.Type II and III capillary pressure curves are common.The quality of reservoir properties is controlled by the size of the throat,the sortability and the degree of connectivity.It is the result of a combination of several characteristic parameters,and has little relationship with a single characteristic parameter.(4)Movable fluid saturation changes greatly(31.72% to 60.89%)with an average value of 44.92%.Reservoir physical properties,microscopic pore throat development,and clay mineral content all have an impact on the content of mobile fluid.The oil-water phase permeation curve can be divided into four types,from the I-IV to the IV-phase percolation curves,the degree of oil-water two-phase interference increases,the scope of the two-phase co-permeation zone narrows,and the residual oil saturation decreases.(5)Based on the classification of reservoirs using various advanced microscopic experimental techniques,with reference to the division results of the reservoir flow units in the study area,the study area 6 reservoirs were divided into four categories from good to poor,in which the type I reservoirs The quality is relatively good,and the difficulty of mining is low;the quality of type IV reservoirs is relatively poor,and the development effect is the worst.