On Sedimentary Facies And Reservoir Features Of Mesozoic Erathem In Wushi Sag In Xingjiang

Well Wucan 1 attained high yield flow of hot gas in 2003, and recently Well Shenmu 1 gains big indicating, which reveals the prelude of exploration and developing upsurge in Wushi Sag. Materials are really limited in research region, and research degree is still low, so we do studies generally basing on two dimensional seism data, as well as 5 wells. To Wushi Sag, it's important to master the distributing bounds of the strata and reservoir features, and to carry out the traps and their structural features, and to submit next optimized target, which help to comprehensively explore and develop Wushi Sag.Through the VSP mark of the wells, and from the profiles through by the wells, we form the framework of seismic explaining profile in this area, and explain structural profiles of seismic profiles here. We finish strata distributing map of Mesozoic and Cenozoic Erathem, structure compendium map and isochronographs of major traps, and definite the structural features of Mesozoic Erathem in Wushi Sag. After observe and describe the cores of 4 wells, we analyze sedimentary facies of single wells and estimate the reservoir, and then complete the sedimentary facies plan and reservoir forecast, as well as discuss petroleum prospect in this region, combined to structural traps. Based on the explanation of three and two dimensional seism data on Landmark workstation, we got new realization on structure and sequence evolution, which direct the study of sedimentary facies distributing.Wushi Sag is Mesozoic and Cenozoic Erathem foreland between South Tianshan and the northern Tarim Basin. Mesozoic Erathem presents mainly in the mid and east of Wushi Sag, whose sediments are controlled by Gumubiezi Fault, the south bound, and is series of sand, conglomerate, mudstone and their transitional rock types. It's continental debris sediments, generally fan delta-lake system. In Triassic, Jurassic, and Cretaceous period, the lake basin expanded and shrank, and the fan and the river moved and mantled, and also there were several structural erosions.Shushanhe formation Cretaceous system is the main reservoir here, is generally thick sediments of sand- conglomerate degree, whose psephicity varies from subround to subangular, and mid-well sorted, and composition maturity differs quite greatly between north and south, and structure maturity is mid degree generally. The sandstone is solidified-subsolidified, and their voids are mainly secondary voids, and the diagenetic stage is Early B. The reservoir is mainly low void- low permeability and very low void- very low permeability types, and meanwhile with great anisotropism. Oil deposits here are extra-deep, with good reservoir-capping equipment, quite poor physical property, and quite stable extent. It has got oil indicatings, is comprehensively estimated as mid reservoir. The optimized areas are structure- lithologic traps of Mesozoic Erathem in the northeast of the sag, anticline belt in the front of South Tianshan, Xigua lithologic trap, and reef limestone of C₂-P₁.