Sequence stratigraphic characteristics and favorable hydrocarbon accumulation prediction of Triassic in Sangtamu area

In order to forecast the favorable hydrocarbon exploration zones of the Triassic in Sangtamu area,Tarim Basin,well seismic calibration is finished using seismic,drilling,logging and core data,the Triassic is divided into one structure sequence,five third-order sequences and nine system tracts,and a high-resolution sequence stratigraphic framework is established. The results show that besides braid delta and lacustrine sedimentary systems which have been recognized before,there also developed meandering river delta sedimentary systems. By studying the sedimentary characteristics and evolution law of key sequences( SQ3 - SQ5) ,and combining it with the comprehensive research of the reservoir-cap combination distribution and the hydrocarbon accumulation conditions,it is held that the braided delta reservoirs are developed in the LTST in SQ3 and SQ5,they are of large thickness and good continuity,but they are not favorable to form lithologic traps. Therefore,rolling exploration should be strengthened in the two sides of fault horst zone to find low amplitude structural traps. The meandering river delta front sand bodies in the LTST of SQ4 were thin and easily pinched out,and they are favorable to the formation of lithologic traps. In the plane,the slope zone in northeast of the fault horst zone is favorable hydrocarbon accumulation zone,and it will be a significant oil and gas exploration target area.