Sedimentology And Shale Gas Accumulation Of The Jurassic In The Northern Qaidam Basin

Sedimentology and sequence stratigraphy of the Jurassic in the northern Qaidam Basin aredeveloped.17kinds of typical sedimentary structures and21lithofacies were identified in theJurassic, which account for the construction of6depositional systems, including alluvial fan,fluvial, braided delta, meandering channel delta, fan delta and lacustrine. Four kinds of markerhorizons were established and second-order and stratigraphic frame were developed.Palaeogeographic maps in systems tracts of third-order sequences of the Yuqia area arereconstructed, and a6-stages model are summarized. Nine shale horizons containing fivelithofacies were identified in the Jurassic of the study area. hydrocarbon potential of these shaleswere analyzed by petrography, distribution, buried depth, organic geochemistry and reservoircharacteristics of that are studied by mineral composition, poroperm characteristics and gascontents. Paleoclimate, tectonic evolution and depositional environments of these Gas-bearingshales were analyzed, and4depositional types of accumulation of shaly horizons were proposed.Analysis above show H1-H3shaly horizons of the Lower Jurassic and H7, H9shaly horizons of theMiddle Jurassic should give a priority for future exploration of shale gas and10favorableprospecting areas are presented.