Oil-gas reservoir-forming conditions and patterns in Lei^hu-Nanbaxian structural belt in the northern margin of Qaidam Basin

Key words:  northern margin of Qaidam Basin  Lenghu-Nanbaxian Btmctural belt  hydrocarix>n reservoir  reservoir-forming

Abstract:

Lenghu-Nanbaxian structural belt, an important region for oil-ga& exploration, is located in the northern margin of Qaidam Basin. The geologic conditions and patterns of hydrocarbon accumulation were researched by using theories and methods of modem i^ervoir fomiationf geophysics t geochemistry t and the data of geology, seismics and analysis 雄say The results show that this area is likely to be large or medium-sized oil-gas field wilh abundant oil-sources, good reservoirs, developed several of effective reservoir-caprock assemblage，multiple types of trap ( especially structural trap) distributing in lines and belts，and good aUc^ation of various reservoir-forming factors. Based on these researches, the reservoir-forming patterns of the Lengbu-Nanbaxian structural belt can be classified as four kinds； near-source fault translc?cation vertical reservoir-forming pattern, far-source unconformity transiocation lateral reservoir-forming pattern, near-source mixed translocation reservoir-forming pattern and near-aource unconformity transiocation vertical reservoir-forming pattern. The near-source fault txans-location vertical reservoir-forming pattern and near-source mixed transiocation reservoir-forming pattern are main reservoir-forming patterns of the area? Near-source unconformity transiocation vertical reservoir-forming pattern can be looked on as exploration direction in future.