Appraisal Of Gas Reservoirs In He 8 And Shan 1 In Block Su 20 Of Sulige Gas Field

Block Su-20 belongs to a typical tight lithologic gas reservoir,which is an unconventional gas reservoir.The distribution of the gas reservoir is strictly controlled by the distribution of sand bodies and physical properties.The core problem of its development is the strong heterogeneity of the reservoir and Changes in microscopic petrological characteristics lead to changes in productivity.In this paper,This paper is based on the characteristics of regional geological background,stratigraphic and structural recognition,Through in-depth and detailed evaluation of structural features,sedimentary microfacies characteristics,and reservoir characteristics of reservoirs,the spatial distribution and connectivity of reservoirs were revealed,and reservoirs were studied.The heterogeneity of the spatial distribution of the parameters The 3D geological modeling of reservoirs was established,and the rules of gas accumulation and the distribution of gas and water were further studied,and gas reservoir evaluation was carried out.which can provide important geological basis and favorable guarantees for the improvement of development effects.Comprehensive research shows:(1)Block Su-20 is located in the west of the middle northern section of the Yi-Shan slope.It is a northeast to southwest inclined monoclinic slope with an average slope of 3-10m/km.Microstructural high sites have a better control of natural gas enrichment.(2)During the deposition period of the member 1 of Shanxi formation,due to the relatively calm tectonic activity,the meandering rivers are mainly distributed in strips near the north-south direction,first member of the shan 1-third member of the shan 1,northern provenance uplift gradually weakened,the rivers continued to recede,the ratio of sand to land was reduced,and some rivers were abandoned and swamped.Entering the Lower Shihezi Period of the Middle Permian,the tectonic uplift was developed mainly in the form of braided rivers,and the braided rivers quickly advanced into the lake and moved frequently in the horizontal direction,forming a nearly north-south reticular pattern.Member of the He 8 Lower 2-He 8 Lower 1-He 8 Upper 2,the northern ancient land gradually rises,the river's effect gradually increases,and the river-delta system advances to the south.At the end of the upper depositional period of HE 8,the supply in the source area of the north and northeast of the study area was reduced,and the pattern of dominant flooding deposition appeared.(3)The sandstone types in member 8 of Xiashihezi formation and member 1 of Shanxi formation are mainly pure quartz sandstone and(lithic)quartz sandstone,and some of them are lithic sandstones.The debris content of Shan 1 is obviously higher.The filler material is kaolinite and silicon.The main cementation is cementation.Five kinds of pores are mainly developed:primary intergranular pores,intragranular dissolved pores,kaolinite intergranular pores,interstitial dissolved pores,and microfissures.The porosity of member 8 of Xiashihezi formation and member 1 of the Shanxi formation reservoir is generally less than 13.0%,and the permeability is generally less than 1mD.It is a low-porosity and low-permeability reservoir.The transformation of sandstone by diagenesis controls the development of reservoirs.Strong compaction and siliceous cementation are one of the main reasons for the low permeability of sandstone in this area.Dissolution is a necessary condition for the formation of effective reservoirs.(4)The main controlling factors for the development of gas reservoirs in the Block Su-20 show that:Among the sedimentary sand bodies in member 8 of Xiashihezi formation and member 1 of Shanxi formation,the physical properties of the sedimentary sand bodies of the heart bank and the edge beach are the best,followed by the bottom sedimentary deposition.The coarse-grained quartz sandstone and lithic quartz sandstone with higher quartz content and less miscellaneous content have good physical properties.In the late stage of diagenesis,dissolution occurred under the action of acidic pore fluids,which greatly improved the reservoir.At the same time,the region with high gas saturation has good conformability with the main body or side edge of the forward structure,and it has good control effect on the local enrichment of natural gas.(5)Based on the above findings,a combination of multi-method advantages,deterministic modeling,and stochastic modeling dynamics and statics are adopted to establish facies control 3D geological modeling.(6)On the basis of a comprehensive analysis of the law of enrichment of reservoirs in the Block Su-20,six parameters,shaly content,effective thickness,porosity,permeability,gas saturation,test gas production,and production capacity were selected as evaluation criteria.Cluster analysis.Type ?,? and ? reservoirs are developed in all small strata,of which the ? reservoir is the most developed in the upper 2nd member 8 of Xiashihezi formation,and the proportion of the ? type reservoirs is relatively the same in the small strata.There are more type ? reservoirs developed in the lower 2 layers member 8 of Xiashihezi formation.