Study On Micropore Structure And Quantitative Evaluation Of NiuJuanHu Oil Field In SanTangHu Basin

The research and quantitative evaluation of the micropore structure of the reservoir are the core contents in the exploration and development of the dense reservoir of xishanyao.Based on the qualitative analysis of the reservoir of xishanyao,the pore structure of xishanyao reservoir is further explored.The pore structure of the target layer was classified and quantitatively evaluated by conventional high pressure mercury injection,constant velocity pressure mercury and nuclear magnetic resonance technology.Get the following knowledge: 1.The lithology of the xishanyao reservoir is mainly feldspathic litharenite,with a small amount of litharenite,and low level of rock composition maturity.The particle size is fine sand to medium sand,and the roundness is mostly subangular-round shape.The types of cementation include kaolinite cementation,chlorite cementation,illite cementation,immiscible cementation,carbonate cementation and siliceous cementation.The average porosity value of the reservoir is 12.4%,and the average permeability is 3.24×10-3?m2,ultra low permeable reservoir.2.The pore types of the target layer are mainly intergranular pores and dissolution pores.There are four types of throat channels: pore narrowing throat,variable section reduction throat,flaps or curved flaps,tube bundle throat.Pore structure type,the north area is mainly pore-microporous,a small number of medium holes;The eastern and southern districts are mainly mesoporous pores,with a small amount of coarse pore development.3.Experimental results of conventional mercury and constant pressure show that,the distribution range of pore radius of reservoir in the study area is that,the north district 80-220?m,the eastern district 90-260?m,the southern district 90-220?m,and the eastern region has the largest pore radius.However,the comparison of throat parameters reveals that the throat radius of the south area and the number of throat are greater than the north and east.4.Nuclear magnetic resonance experimental research shows that the value of mobile fluid saturation in the north region is between 35.44-55.01%,with an average of 46.61%.The eastern district is between 38.68-59.27%,with an average of 48.04%.The southern district was 51.36-62.32%,with an average of 57.09%.According to the analysis of all samples,the north and east side reservoirs are defined as class ? reservoirs,and the southern region is the class ? reservoir.5.The densification of the objective layer is mainly sedimentary and diagenetic.The conclusion is that:(1)the initial porosity of the north district was 38.22%,the compaction effect decreased by 20.78%,the cementation effect decreased by 4.3%,and the dissolution rate increased by about 4.24%.Finally,the porosity value is 10.71% and the measured porosity is 10.86%.(2)The initial porosity of the east side was 38.57%,the compaction decreased by 20.44%,the cementation loss was 4.9%,and the dissolution rate increased by 5.66%.The theoretical calculation of porosity is 13.21%,and the measured porosity is 13.01%.(3)The initial porosity of the southern region was 38.9%,the compaction effect decreased by 18.33%,the cementation effect decreased by 5.3% and the dissolution rate increased by 5.27%.The final theoretical calculation of porosity is 13.55%,which is 0.15% different from the measured porosity.