Abstract:

Tiemulike Formation in the Permian above Yining depression is mainly composed of hydrocarbon source rocks which has formed two complete oil-bearing systems of P_2t-P_2t self-generation & self-reserving and P_2t-T_2-3 lower intervals generation and upper interval reserving. The former system is a known system proved by drilling; the latter system is a system by deducing. The basin thermo-modeling results and comparatively analysis with Junggar basin indicate that the Permian oil and gas-bearing system in the depression had entered into hydrocarbon generation threshold by the earlier Triassic and had reached the peak of hydrocarbon generation by the earlier of the middle Jurassic and had ended oil generation and then gone into gas generation by the end Jurassic. Large scale of oil and gas generation and migration occurred in J₃-J_1-2,the last Indo-China episodic tectonic movement(208Ma up to now) is a key movement of the system. The southern slope in the depression is believed to be a favorable region for the exploration of oil and gas on the basis of multi-analyses of the degree of oil and gas-filling, migration direction and trapping conditions etc.

Key words: Permian, oil and gas bearing system, Indo-China movement, Yining depression