Study On The Characteristics Of Carbonate Reservoirs In Area A On The Right Bank Of The Amu Darya River

Carbonate reservoirs in area A on the right bank of Amu Darya are mainly developed in the shoals and reef facies of the platform margin,and the reservoirs show heterogeneity and variations in the spatial direction.Therefore,the study of sedimentary facies and reservoir characteristics is significantly important for the development strategy in the study area.The target layer of this study is the anhydrite limestone interlayer(XVac),bedded limestone(XVp)and massive limestone(XVm)of Callovian-Oxfordian in the Upper Jurassic.The paper integrated sedimentology,petroleum geology and reservoir geology,to analyze facies,petrophysical properties and reservoir types using seismic,drilling,logging,coring,section analysis and laboratory tests.The reservoir distribution patterns are further discussed.The main conclusions are as follows:1.The main sedimentary facies types in the study area are identified,and the main characteristics of platform margin shoal and reef faciesare fine described.The study of sedimentary facies in the XVac,XVp and XVm layers indicates that the facies of favorable reservoir is mainly located in the high positions of the S,M,Y structures.The established facies model is characterized wih evaporation platform,limited platform,open platform,platform margin and front edge slope.2.The main reservoir lithology include bioreef limestone and grainstone,and the main reservoir space are dissolution pores or vugs with good pore structures,thus the carbonates are classified as pore or hole reservoirs.The XVac dominates as porous fractured reservoir with poor petrophysical properties,thin thickness and discontinuous patterns.The XVP is porous reservoir and the petrophysical properties in the upper part are better owning to the thickness and distribution patterns.Furthermore,the XVm is vug reservoir and acts as main reservoir layer,having better petrophysical properties,larger thickness and stable distribution.3.The total thickness and the porosity patterns in the XVac,XVp and XVm indicate that the high parts of the S,M and Y structures have developed high-quality reservoirs,which demonstrates the controlling of sedimentary facies to the reservoir distribution.