Abstract:

The formation of shallow-layer oil and gas pools is controlled by structure and depositional cycles. Under specified geological and structural conditions,shallow-layer oil and gas pools may form whether in inherited depressions of oil generation, or in the depressions formed during the later period. Immatured crude oil is recently discovered above the depth of oil generation threshold (2200m) in the Jianghan Basin except matured crude oil produced by washing oxidation or biodegradation. They can be divided into two types such as in situ oil and heterotopical oil based on their migration and accumu-lation. There are geological and geochemical environments to form shallow-layer oil and gas pools in the Jianghan Basin. Potential areas for shallow-layer oil and gas exploration are mainly in the slope zones, marginal fault zones, erosional areas and uplift zones adjacent to oil-generating depression.