Abstract:

The Es₃⁴ submember in Wenliu area is a typical salt lake deposit. The rock salt js of great thickness, high purity and wide distribution. The uneven elevation and subsidence of basement fault blocks led the saline formation to varyin buried depth. Under differential compaction, the plastic rock salt flowed towards the structural apex along horizones and locally concentrated. And then,the arching of the salt body made the overlying formations curve, deform andfracture, thus forming salt domes. The salt dome apex slumped under gravityand arching force and formed a salt anticline. Subsequently, the overlying cover on the salt dome resulted in graben-subsidance and made the salt anticlinemore complecated due to the tensil force. Other structures associated withsalt flowage are: salt pillow-"pillow like" salt enrichment formed in the flowdirection due to fault or hard formation barrier: salt wedge- "wedge shaped"intrusion of salt flow along fault fracture zone; slender shin deformation-locally thinned formations due to salt loss. The salt flowage phenomena mention-ed above provided various types of traps for hydrocarbon accumulation later on.These traps, in conjuction with favourable oil-generation condition, made Wenliu area become the most abundant place in hydrocarbon resources of the whole depression.