Faults developed very well in Tarim Basin. The control of the faults over oil and gas would principally be realized by carrying and sealing. The carrying could be seen by following: (1) abundant hydrocarbon seepages occurred along faults: (2) alternation presented in carrying oil and gas: (3) connecting underlying source rocks with overlying reservoir : (4) faults cut numerous source beds of different kerogens

thus resulting in the mixing of source rocks of various attributes. The sealing may be distinct from each other due to the differences betweene geometric and kinematic properties of faults and fault systems. The sealing of normal faults is closely related to intra-fault material flowage and the butt joint of the lower wall reservoir with the upper wall argillite: the sealing of abnormal faults is related to the gouge

mylonite within the faults

and the butt joint of reservoir on one side of a fault with the impermeable rock on the other side. Larger faults usually have carrying function on hydrocarbon

and smaller faults generally have sealing function.