Salt-related Structural Characteristics and Hydrocarbon Accumulation in the Middle Segment of the Kuqa Foreland Fold Belt in the Northern Tarim Basin, NW China

Thick salt beds of the Lower Tertiary are developed in the middle segment of the Kuqa foreland fold belt in the northern Tarim basin. The Meso-Cenozoic structures of the Kuqa foreland fold belts can be divided into three large horizons based on the salt beds, i. e. , suprasalt structures, salt bed structures and subsalt structures. The suprasalt structures include salt anticlines, thrusts and fault-related folds, suprasalt pop-up, forced folds, thrust screened structures and salt nappes. The salt bed structures are mainly salt pillows, interbedded thrust-folds, salt welds and allochthounous salt sheets. The subsalt structures mainly include popup structures, fault-related folds, imbricated thrusts and duplex structures. The Formation of the salt tectonics in the Kuqa foreland fold belt may be controlled by compression, gravitational gliding and gravitational spreading. The hydrocarbon accumulation conditions and models of the salt-related structures are discussed in the paper. Structural traps have a bearing upon salt beds in the middle segment of the Kuqa foreland fold belt. The source rocks are mainly located below the salt beds that can act as excellent caprocks and seal of the oil-gas pools. Thrust faults cutting through salt beds play an important role in controlling suprasalt, salt beds and subsalt petroleum accumulation. The subsalt horizons are the favorable place to find out oil-gas pools.