Genetic Model Of The Reservoir Architechture Within The 'Donghe Sandstones' In Tarim Basin

‘Donghe sandstones' is typical marine clastic sediment and one of the most significant exploration and development targets in Tarim Basin.Superposition of sand body causes the complexity of oil-water distribution in current situation,so further understanding of reservoir architecture is crucial to reservoir of this kind.However,studies on marine wave-dominated littoral deposits mainly focus on the level of composite sand bodies.The inner architecture pattern is an unsolved scientific problem,which greatly confined further development and potential tapping of the remaining oil.On the basis of sequence stratigraphy correlation of ‘Donghe sandstones',this thesis revealed depositional mechanism of wave-dominated seashore in different sedimentary backgrounds,using data from outcrops,cores,seism,well-logging,etc.and made further dissection of wave-dominated littoral sandstones with the analysis of outcrops and subsurface reservoirs,thus established the wave-dominated littoral sand body architecture of ‘Donghe sandstones'.Through analysis of controlling factors like relationships between material supply and sea level fluctuation,hydrodynamic force conditions and ancient landform features,combined with sand body distribution and sedimentary features of different study area,we raise the genetic model of wave-dominated littoral ‘Donghe sandstones' deposits: wave-dominated littoral deposit with reworked delta background in Donghe 1 area;transgressive-regressive wave-dominated littoral deposits with shoal background in Hudson area;transgressive wave-dominated littoral deposits with gentle-slope background in Tazhong 4 area.Under the guide of genetic model,with abundant static geology data,dynamic data and outcrop data of Xiaohaizi,three levels of architecture are studied in ‘Donghe sandstones',which are composite sand bodies,single sand body and internal component unit.Flow barrier usually develops along different levels of architecture interface,including original deposit type,secondary diagenesis type and hybrid genesis type.The prediction method of its spatial distribution is raised in this thesis,based on dynamic and static pattern constraint.Composite sand bodies contains elements like bar sand(BA),beach sand(BE)and flute deposit(TH),and is characterized by contiguous superposition and lateral migration.Its superposition patterns are concluded as regression,transgression and aggradation,according to the relationships between material supply and sea level fluctuation.Based on depositional genetic model,genetic types of internal component unit are identified,and inside composite sand bodies,three methods are concluded to identify single sand body and its inner unit,which are pattern matching control,surface identification using well data and production data analysis.Single sand body in regressional composite sand bodies has three types of spatial distribution pattern,which are contiguous onlap,step migration and filling thick layer.While,that in transgressional composite sand bodies are thick layer accumulation,step migration and contiguous superposition.Internal component unit has two types of accumulation pattern: seaward migration and landward migration.On this basis,allowing for flow barrier genesis and distribution feature,spatial relationship and pattern of reservoir architecture elements in ‘Donghe sandstones' are established.Architecture elements of different levels have distinct influence on the remaining oil.The affection of composite sand bodies mainly reflects on horizontal block,horizontal facies change(cause differences in porous flow)and vertical facies change(cause interlayer disturbance).The affection of single sand body level mainly reflects on sand rhythm,slant barrier and superposition pattern.The affection of internal component unit level mainly reflects on development extent of flow barrier and rhythm.