Hydrocarbon accumulation mechanism of tight sandstone reservoir in Jiyang Depression

The permeability of tight sandstone reservoirs is below 10×10^-3 μm². Due to the particularity of reservoir space type and characteristics, the tight sandstone reservoirs are different from normal ones in hydrocarbon accumulation mechanism. The generation conditions and accumulation features of "source-contacting gas" are studied. Based on simulation experiments, hydrocarbon accumulation mechanism is concluded according to the features of tight sandstone reservoirs in the Jiyang Depression. Overpressure charging is the main way of hydrocarbon migration and accumulation in tight sandstone reservoir. The border for overpressure transfer is the boundary for oil or gas. When overpressure gradient is larger, the distance of hydrocarbon charging and the range of trap will be larger, and the hydrocarbon saturation will be higher. Through similarity research, the tight sandstone reservoirs in the Jiyang Depression have the following characteristics. 1) Source rocks contribute to hydrocarbon continuously. Large quantity of oil and gas with poor diversity exist in source rocks or neighboring reservoirs. 2) In tight sandstone reservoirs, facies and potential control accumulation. 3) Tight reservoirs may exist widely, indicating for good exploration potential.