The Study Of Reservoir Forming Rules Of Permian In Wu-Xia Area, Junggar Basin

Wu–Xia area is one of the second structure units in the north-western slope of Junggar basin,with abundant hydrocarbon resources.After a fifty-year exploratory development,it has come into high ripe exploration phase for Triassic and Jurassic.The degree of exploration for Permian is very low,although it contains two oil-gas bearing systems,so it is necessary to study on Permian systematically . Summarizing the regularity of hydrocarbon enrichment,clearing the main controlling factory of reservoir formation,establishing accumulation modeland showing clearly direction for next exploration strategy could provide geological basis for enhancing oil recovery of oil field.In accordaning to sequence stratigraphy principle and the means of well-to-seismic integration,10 sections have been divided for Permian,3 for wuerhe formation,2 for ziazijie formation,3 for fengcheng formation and 2 for jiamuhe formation,and isochronous stratigraphic framework has been established successfully for Permian.The formation of Permian presents the character of north thick—south thin and east thick—west thin.Combining with core,well logging and mud logging data etc,and analyzing sedimentary facies of single well and well tie,sedimentary system is researched systematically in unit section referring to the percentage content of sandy conglomerate.In early Permian,the main deposition is sustained lake facies deposit then there developes fan-deltaic in middle-late Permian,with character of fan-delta front widely developing.There are two chief source rocks of wuerhe formation and fengcheng formation in Permian,so oil source is sufficient.Its reservoir lithology is variegated,mainly containing 3 kinds:terrigenous clastic rock reservoir,volcanic reservoir and dolomite reservoir,the former distribute typically in wuerhe formation,and the later two mainly in fengcheng formation.It develops 4 sets of favorable reservoir-seal assemblage in Permian,according to the time mutual dispose relation between them,3 kinds of source-reservoir-cap assemblage are divided,self-souce and self-reservoir,the normal and lateral variant.2 types of reservoirs are found by reservoirs anatomy:structural reservoir and structural-lithologic reservoir.In the plane,reservoirs mainly distribut in wuerhe fault-fold belt based on structure background of big Anticline in wuerhe,while enrich in xiazijie formation and fengcheng formation in the longitudinal direction . There are four influencing factors for reservoir , structure background decides petroleum relative accumulation,fracture controls its vertical migration-accumulation,unconformity controls its lateral migration-accumulation,favorable Reservoir controls the enrichment extent of hydrocarbon,moreover,the last is the major control factor.After summarizing pool-forming pattern,the author considered that it is advantageous to search stratigraphic reservoir rand lithologic reservoir in slope areas and structural reservoir or combined reservoir correlated structural in fault zone.Based on the above comprehensive study,2 favorable targes are predicted:fengnan3 fault-block in wuerhe formation,volcanic traps in fengcheng formation in xiazijie area,which show clearly direction for next exploration strategy in Permian.