Abstract:

WenJisang braid delta system in Taibei Sag, Turpan-Hami Basin consists of delta plain, delta front and prodelta. The main sedimentary characteristics of the system are:1.Braid river deltas that lack meandering river facies are a incompletely developed deposition system.2.Sediments are characterized by coarse grain size,lower mineralogic and textural maturity.3.Subaqueous distributary channel deposits developed well in delta front,they are usually superimposed to form huge thickness of sequences.4.The delta front usually formed in lake basin margin. Braided river channels prograded towards lake basin and transported laterally in Middle Jurassic,thus forming a large sheet sandbody. Coal measures of Lower-Middle Jurassic are the most important hydrocarbon generation interval;Middle Jurassie subaqueous distributary channel is the main reservoir interval.Upper Jurassic brown-red mudstone could be fine regional caprock.They constitute a complete source reservoir-cap rock assemblage.