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The Research Of Characteristic Of Xujiahe Formation Reservoir In Dayi Structure Of The Western Sichuan Depression

Posted on:2010-05-09Degree:MasterType:Thesis
Country:ChinaCandidate:Q HuangFull Text:PDF
GTID:2120360278960636Subject:Mineral prospecting and exploration
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Reservoir is the chief research object of hydrocarbon exploration and development. Reservoir evaluation is the core content of reservoir description. The forecast of favorable zone for reservoir prospecting is the ultimate goal of petroleum geology through a integrated research.In this thesis, Xujiahe formation is the study object,which located at Dayi structure in the Western Sichuan Depression,Sichuan Basin.Based on the previous studies, petrology, diagenesis and reservoir characteristics of Xujiahe formation were described systematically using lithologic character, physical property and electrical property datas.Then, a comprehensive reservoir evaluation was made.The main control factors for superior quality reservoir were summarized. As a result, the favorable zone for reservoir development in study area was predicted.Dayi structure is the major local structure in the buried structure belt located at the front zone of Longmen mountain. Xujiahe formation is divided into four members in this area,named Xujiahe2,3,4 and 5 respectively. This study lays special emphasis on Xujiahe 2(Xu2 for short) ,Xujiahe 3(Xu3 for short)and Xujiahe 4(Xu4 for short). Research result suggests that study area mainly developed delta sediment in the host of Xu2 to 4.The property of reservoir is controlled by sedimentary facies obviously.The most favorable subfacies is delta plain and delta front.And distributary channel and natural levee in delta plain, distributary channel in delta front are the most favorable microfacies.The rock types of Xujiahe formation mainly include lithic quartz sandstone,feldspar lithic sandstone,lithic sandstone,feldspar quartz sandstone, lithic feldspar sandstone, feldspar sandstone and so on.In these 6 kinds of rock types, lithic quartz sandstone,feldspar lithic sandstone and lithic sandstone are dominant.From Xu2 to 4, compositional maturity and textural maturity become bad gradually. The characteristic of detrital component is rich in debris and poor in feldspar. Interstitial material mainly contain carbonate, kiesel and clay mineral.There are 2 kinds of diagenesis in study area, destructive diagenesis and constructive diagenesis,which divided by the effect to reservoir. Destructive diagenesis include compaction, pressolution, cementation.While, constructive diagenesis include denudation and tectonic cataclasis.Wholly,Xujiahe formation in study area belongs to B period of middle diagenesis with high evolution in diagenetic stage.Denudation in the late period of early diagenetic and early period of middle diagenetic, cataclasis in the late period of middle diagenetic play a important role in reservoir improvement.In study area, the reservoir of Xujiahe formation located at Xu2 to 4 principally.The range of reservoir thickness is from 391.48 to 648.52m.With low porosity and permeability reservoir in general,its physical property become poorer gradually from Xu2 to Xu4.Horizontally,Dayi 101 and Dayi 4 possess better properties. Porosity range 0.57-7.99%, average 2.65%, bimodal distribution, the main peak is 1-3%.Permeability is less than 0.5md generally, accounting for nearly 90%. The main reservoir space consist of intergranular dissolved pore and fracture.The chief types of reservoir are pore reservoir and pore-fractured reservoir.The characterizer of Pore configuration is high expulsion pressure.The types of consociation is six, including mesopore-slenderthroat, macropore-microthroat, macropore-slenderthroat and so on.With mesopore-slenderthroat dominanted, pore structure is not fine. The type of reservoir space is simple.Intergranular dissolved pore, dissolved pore and fracture is the main reservoir space.The degree of development of dissolved pore and fracture determines the reservoir property.Combined with the actual geological conditions,reservoir categories and valuation criteria are proposed.The categories of reservior in Xujiahe formation can be divided into four kinds, I, II, III, IV ,and a comprehensive reservoir evaluation for Xu2 to 4 is made.Finally,this paper points out the favorable reservoir distribution. The main control factors of reservoir is summaried systematically : favorable sedimentary facies (microfacies) master reservoir distribution macroscopically, diagenesis is an essential factor to dominate the reservoir property, tectonism and cataclasis is the key to the formation of reservoir.
Keywords/Search Tags:Dayi Structure in Western Sichuan Depression, Xujiahe Formation, Tight Sandstone Reservoir, Reservoir Characteristic, Reservoir Evaluation
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