| Daniudi fields was located in Tabamiao area in the northeast of Erdos Basin,which is of the tight sand reserior and having the srong heterogeneity,Tectonic position is in Yishan slope,a gentle structre,contained a little fault.In Shanxi Qi,sedimentary environment located braided river delta plain into lake,and varied sharply in different periods resulted in obvious migration of sand body and strong heterogeneity.Along with exploration degree,exploitation degree and the difficulty of exploiting increased,detailed evaluation of the characteristics of sandstone reservoir is increasingly important. The thesis aims at comprehensive evaluation in the Shan2 section on the basis of former studies about identification method and technical research through studied the ‘four properties’ of gas reservoir in detail,using gas accumulation of a large number of cores, well logging and mud logging data, description of reservoir heterogeneity basic geological and reservoir characteristics, combined with the characteristics of gas reservoir development, establish a reasonable classification evaluation criteria, Daniel to Shan-2 gas reservoir comprehensive evaluation, a clear layer of the lower production, and reservoir classification evaluation, to ascertain the distributioncharacteristics of the mountain two segments of the small layer of gas reservoirAccording to the descriptions of the coring data of 22 well and the observation research of 384 sandstone thin section and the casting thin sections, we come to the conclusion that thesandstone type of Shan-2 section are mainly made up of quartzlithic sandstone and lithic quartz sandstone, which have a complicated diagenes, pore types and varied, and its main pore types were primary pore, secondary dissolution pores. The porosity of Shan-2 section areranged from 2% to 8%, unimodal mainly within the 4% to 8%, which accounted for about 45% of the total, and porosity is about 6.49%. From the point of permeability, the maximum value of permeability is 0.48, and the minimum is 0.1 ×10-3μm 2Combined with rock pressure mercury data analysis,we can havea good known that this section have appearedmany reservoirs such as Ⅱand Ⅲ, and its lithology is mainly in the medium-fine sandstone, and sandstone pore structure characteristic separation medium to poor and poor structure.On the basis of analyzing reservoir characteristics, with the research of 80 wells in this section we come to some conclusionsthat,(1) from the point of rock electricity relationship, this high quality gas reservoirs prone to have a sidewall instability and disruption due to their high shale content slightly, and acoustic curves appeared to frequency hopping, which lead toa inaccurate permeability interpretation.(2) from the perspective of the relationship of lithology and physical property, the segment sedimentary energy overall is low,the quality of sand body is lower, and reservoir petrology characteristics of sedimentary formation is not enough to cause pore property changes.(3) from the point of property- gas-bearing characteristics, shanxi group belongs to combination accumulation within the oil source in reservoir formation combination, In the combination within the source of accumulation, migration pathway and the influence of air condition is more weak, the influence on the physical properties in more stronger, which also creates a situation that period of physical distribution is relatively concentrated and bad, so is not obvious for the relationship with hydrocarbon showings as a whole.It builds a logging interpretation model about mud, porosity, permeability and gas saturation on the basis of "four properties". Then further to evaluate the reservoir, through the comprehensive evaluation and well logging response-porosity and permea-bility fitting and other methods, it makes sure that the lower limit of porosity of Shan 2 reservoir is 5%, and permeability is 0.14×10-3μm 2, also, it establishes the reservoir classifi-cation and evaluation standard: Class I gas reservoir, porosity is not less than 7% and permeability is not less than 0.3×10-3μm 2.And the gas saturation is greater than 65%, belonging to the high yield region; Class II reservoir, porosity is 7%~10%, permeability is(0.3 ~ 1) ×10-3μm 2. And the gas saturation is 55%~70%, belonging to the middle area; Class III gas reservoir,porosity is lower than 8%, permeability is lower than 0.6×10-3μm 2. And the gas saturation is less than 65%, belonging to the low yield area; Class IV gas reservoir, porosity is lower than 5%, permeability is lower than 0.14×10-3μm 2.And the gas saturation is less than 50%.The stable gas distribution area of Daniudi Shan 2 section of the Shanxi group gas reservoir is mostly developed in the area where sand bodies are distributed stably, which layers are more thickness and with good lateral continuity. Class I gas layers of S2-1 are basically scattered in the Midwest, respectively near to 1-1-35, 1-3-7, 1-1-68, near 1-2-9, 1-2-10 wells. Class II is relative concentrated distributed in D12 and D15 wells. Class III is sporadic distributed in D47, D66 and D4 wells, it can be seen obviously that the distribution range is controlled by sand bodies, strong heterogeneity, poor lateral continuity, with a contrast in the range of 2km-5km.S2-2 gas distribution compares with S2-1, the distribution range of Class II is larger, and Class I is mainly distributed in D55 of northeast, D13 of central, 1-4-27 of southwest and 1-4-17. Class II is about half of class III gas layer, which mainly distributed in rivers of north and south, divided into the wells of D44, D16, D31, D38, D14 line of central western, D28, D32, D8, D13, D22 and D61 wells line of central north-central south, and the wells of D77, D84 of south west nearby wells. Besides D90 of northwest, D57 of norteast, D74, D121 and D63 of southwest nearby wells, class III is basically same with class II. |
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