The Study Of The "four Properties" Relations Of Sandstone Reservoir In Shanxi Formation In Daniudi Gas Field

Of the tight sand reserior and having the srong heterogeneity Daniudi fields waslocated in Tabamiao area in the northeast of Erdos Basin.Tectonic position is in Yishanslope a gentle structre contained a little fault.In Shanxi Qi sedimentary environmentlocated braided river delta plain into lake and varied sharply in different periodsresulted in obvious migration of sand body and strong heterogeneity.Along withexploration degree exploitation degree and the difficulty of exploiting increaseddetailed evaluation of the characteristics of sandstone reservoir is increasinglyimportant.The thesis aims at comprehensive evaluation in the Shanxi group gasreservoir in Daniudi gas field through studied the ‘four properties’ of gas reservoir indetail and classification evaluation in reservoir make clear the plane distributioncharacteristics of gas sand in Shanxi group.The Shanxi group sandstone is principal in quartzy rock-fragment sandstoneLithic quartz sandstone with complex diagenesis and a wide varity of pore typeswhich is principal in the residually primary pore and secondary dissolution pore.Afterstatistical analysis of Shanxi group sandstone samples from more than40wells foundthe average porosity in Shan1section sandstone is7.5%porosity mainly distributed inthe range of6to8percent average permeability is0.69mD permeability maindistribution range of0.1to1mD; average porosity in Shan2section sandstone is7.6%the main porosity distributed in the range of6%to8%average permeability is0.54mDmain distribution area is0.1~0.5mD.Combined with the Shanxi group sandstone ofmercury injection data analysis shows that the pore structure of sandstone belongs tosandstone of the poor of size sorting and maturity of structrue.On the basis of the analysis of reservoir characteristics on the basis of the Shanxigroup studied the relationship of " four properties".After made study of therelationship of lithologic and physical properties found that (1)quartz sandstone and lithic quartz sandstone have better porosity than lithic sandstone.but the difference ofpermeability is not large;(2)porosity and permeability decrease with paticle sizedecreasing;(3)the good relativity of physical properties and electrical properties ofsandstone of different types is up to more than80%;(4)we can distinguish differenttypes of sandstone very well by logging response especially in making use of GR-PEintersection diagram although other logging response intersection diagram candistinguish different types of sandstone but the effect is limited;(5)the good gasbearing sandstone in Shanxi formation is principal in the gravelly coarse sand andcoarse sandstone next is medium sandstone and fine sandstone all the reservoir ofsiltstone are dry layer or poor.On the basis of the research in the relation of “four properties” the authorsestabilished a series of log interpretation model of clay content porosity permeabilitypore structure irreducible water saturation and gas saturation.After to further andcomprehensively evaluate the reservoir the author make sure that the lower limit ofthe reservoir physical properties is porosity of5%and permeability of0.108md(Shan1) and0.14md(Shan2) in the Shanxi formation made use of fitting logging responseand porosity-permeability and to have the establishment of a classificationevaluational criterion on reservoir:Class reservoir-porosity of7.5-12%permeability0.5-2.4md gas saturation up to60-90%;class II reservoir-porosity5-10%permeability0.5-1md gas saturation50-70%;class III reservoir-porosity4-8%permeability0.3-0.6md gas saturation40-60%; class IV reservoir-porosity2-6%permeability0.01-0.5gas saturation30-50%.Stably yielded gas reservoir in ShanxiFormation in Daniudi gas field mainly distribute among the area of thick sand layerwith good lateral continuity Class reservoir mainly distribute in the middle ofDaniudi gas field such as the Da12wellblock in the southeast area Da3wellblockin the east Da70wellblock Class reservoir distribute in the north and southeastClass III IV reservoir are widely distributed in the whole region.