Discovery significance of Triassic dark mudstone rich in organic carbon, well AB1, Avat area, Tarim Basin

In well AB1 of Avat area of the Tarim Basin,lacustrine dark mudstones rich in organic carbon have been found in Triassic.The abundance of organic matter pyrolyzed from rock ranges from medium to high; however,the organic matter is still in the immature and low-mature stages.Studies of sedimentary,tectonic background and thermal evolution history have indicated that several factors control the generation of effective source rock in Triassic of the platform-basin region.1) The deep and half-deep lacustrine facies are the most favorable,and the shore and shallow lacustrine facies the second.2) Dark mudstones should be thick and widespread enough.3) Buried over 5 500 m deep.During the early Triassic,Avat area was in lacustrine background.Triassic in the study area is buried deep presently.According to thermal evolution simulation as well as studies of seismic and sedimentary facies,the area of effective source rocks in Avat is 2 600 km².