ANALYSES ON OIL AND GAS EXPLORATION PROSPECTS IN THE ZHOUKOU RESIDUAL BASIN

The reformation characteristics of three-period compression and two-period extension suffered by the prototype depositional basin of the Zhoukou Depression were analyzed in this paper at first.Then two groups of major residual oil source rocks in the Lower Cretaceous and the Carboniferous-Permian were determined through oil-source correlation.According to the relations of "construction to reformation" and "destruction to preservation",four kinds of pool-forming units were identified,the thermal evolution history of petroleum systems in the residual basin was analyzed,and three types of hydrocarbon accumulation patterns such as "self-generation and self-preservation","generation in lower zones and preservation in upper zones" and "fossil buried hills"were predicted.The authors emphasized that the inhomogeneity of thermal evolution created certain conditions for secondary oil generation,and the strength and range of secon-dary oil generation were controlled by the Early Tertiary fault structures in overlying formations.So the secondary oil generation and the pool-formation in late periods were determined as main research directions for further exploration.To study the necessary conditions of "oil generation in lower zones and preservation in upper zones" and the favorable occurrences for pool formation in later periods can help us to exactly find the breakthrough points of hydrocarbon exploration in residual basins.