| In our country,the deep exploration degree of the Ordovician in the Tahe Oilfield is relatively low,the basic research is weak,for example,the reservoir type,the genesis and development mode of the reservoir,the distribution law and the main control factors are not clear.Therefore,In this thesis,the Yingshan Formation-the Xiaqiulitage Formation in the Tarim Basin is the research stratum.The main research area is Tahe Oilfield.Based on the literature data collection and sampling analysis of correlated well,and the theory of oil and gas reservoir geology,combined with oil and gas reservoir tectonics,sedimentary petrology,lithology paleogeography and other disciplines theory,the characteristics of deep carbonate reservoir in Tahe area are described and the main controlling factors of reservoir are analyzed and studied.Tahe area of Yingshan Formation-the Xiaqiulitage Formation reservoir rocks are limestone,including grainstone,granular microcrystalline limestone,granular limestone,micriteand so on.Next is dolomite,it is mainly divided into four categories,they are non-flat crystal surface xenomorphic-flat crystal surface hypidiomorphic-fine crystal dolomite;flat crystal surface hypautomorphic-euhedral fine-Microtek dolomite,hypautomorphic of non-planar-xenomorphic fine grained dolomite and non-flat crystal surface coarse grained dolomite.There are many types of reservoir space in the study area,including intergranular pores,intergranular dissolution pores,fractures and dissolved pores.This shows that the formation of the reservoir is not a single.Based on the division of sedimentary facies of single well in study area,and the distribution of sedimentary facies plane,it is considered that the Middle Ordovician strata in Tahe area is mainly based on carbonate platfonn sedimentary system.The Penglai dam group revealed less wells,however,on the basis of this study,the study of S88 well and TS2 wells revealed that the Penglai dam group mainly developed lamellar dolomite,which has typical tectonic structure,therefore,S80 wells and TS2 well areas should be limited to Taiping deposition.During the deposition period of the Yingshan Formation,the subfamily development of Taiping and Taiban Shoal is in the open platform environment,and the tidal phase can also exist at the top of the local shoal,and the transitional lithofacies type appears with the shallow water.For the limestone,the post-diagenetic effect of the destruction of the reservoir is mainly composed of cementing,compaction pressure,recrystallization,silicification,sedimentation(calcite)filling,and so on.And the post-diagenetic effect of improving the reservoir performance mainly has the effect of dissolving,dolomizing and rupturing.The dissolution pore formed by the uplift of the middle Caledonian and Early Hercynian is the main reservoir space of Ordovician in this area.For dolomite,diagenesis mainly has the effect of compaction and pressure,dolomitization,cementation,excessive dolomitization of reservoirs,new deformation and recrystallization of dolomite,silicification and siliceous Filling,other authigenic minerals,and in the dolomite formation plays an important role in the rupture.The Ordovician strata in the Tahe area experienced a multi-stage tectonic movement,but the early tectonic uplift of the Caledonian-Hercynian tectonic uplift was the most significant tectonic movement in this area and the most important period of karst development.So it is subjected to severe weathering and denudation,but the tectonic uplift is different in different regions,so the Ordovician strata of different horizons are left.The strong tectonic movement in the early Hercynian area has been strongly eroded,and the denudation from the south to the north has gradually become larger.The middle and lower Ordovician in Tahe area was eroded,exposed to the surface,and suffered from fresh air erosion.Under the background of large tectonic uplift,a number of secondary.tectonic activities are relatively stagnant,resulting in the formation of karst caves. |
PDF Full Text Request