Reservoir-forming Conditions Of Shanxi-upper Shihezi Formation In Yan223 Well Of Yichuan Area,Shaanxi Province

Based on previous studies,under the guidance of sedimentology,reservoir geology,petroleum geology and related disciplines theory and methodology,using the abundant data and materials from drilling,logging,testing and producing analysis,this thesis comprehensively studies the reservoir-forming conditions of Shanxi-Upper Shihezi Formation in yan223 well.Mainly achieves the following understanding:1.By the detailed analysis of geochemical characteristics of source rocks,it is found that the organic matter abundance of source rocks in Shanxi Formation(TOCa,erage=0.91%)is higher than in Lower Shihezi Formation(TOCaverage=0.42%),and the organic matter abundance in Lower Shihezi Formation is higher than in Upper Shihezi Formation(TOCaveege=0.09%).Kerogen in lower Shihezi Formation is of type ?2??,most of which is of type ?,and most is at over-mature stage,few of it is at high-mature stage(Roaverage=2.33%),in which the gas is mainly generated.Most of kerogen in Shanxi Formation is of type ? and at over-mature stage(Roaverage=2.39%),and in which the gas is mainly generated.2.According to the core analysis,cast information sheets as well as information on mercury,we have known that rock types of Shanxi Formation are mainly medium-fine grained and medium-grained quartz sandstone,the main component of interstitial material is calcite and hydromica.Rock types of Shihezi Formation are mainly medium-fine grained lithic sandstone and quartz sandstone,the main component of interstitial material is calcite and kaolinite.The types of pore combination are mainly dissolution pores;the dissolution-intergranular pores are very little.3.By analyzing the macrofeature and microscopic feature of reservoir,it is revealed that the reservoir physical property of Upper Shihezi Formation(porosity average is 5.9%,permeability average is 0.38×10-?m)is better than that of Lower Shihezi Formation(porosity average is 5.1%,permeability average is 0.21 ×10-3?m2),and the reservoir physical property of Shanxi Formation is the worst(porosity average is 2.0%,permeability average is 0.12×10-3?m2).The relationship of porosity and permeability is positive,and the reservoir physical property lower limit is delimited,the porosity lower limit is 3%,permeability cutoff is 0.1×10-3?m2,and heterogeneity of sandy reservoir is very serious.4.Studying the parameter of pore and permeability comprehensively and reference to previous research about the evaluation of reservoir,the reservoir is classified four types.Type ?b is the mainly gas bearing reservoir,developed in the subaqueous distributary channel environment of Lower Shihezi Formation and the shore meare facies of Upper Shihezi Formation.Type ?a developed in the shore meare facies of Upper Shihezi Formation.Type ?b developed in the subaqueous distributary channel of delta front environment of Lower Shihezi Formation.Type IV developed in the delta plain environment.5.Based on the above research achievements,the play of Shanxi-Shihezi Formation is divided,Shanxi Formation is self-producing and self-reserving reservoir,Shihezi Formation is below-producing and above-reserving reservoir.