In order to analyze the influence factors of threshold pressure gradient value for tight sandstone, this paper studies the experiment equipment control mode and petro?鄄physical parameters. Result shows that the constant pressure injection fluid can reduce the experimental error caused by using different experimental methods in net confining pressure mode. Measured results under constant confining pressure are big. The different injection methods have little impact on threshold pressure gradient values. The real threshold pressure gradient increases with the increase of water saturation. After reaching the maximum, it reduces gradually. For the core with high permeability, the threshold pressure gradient at the same water saturation is small. It can reduce with the increase of movable fluid saturation and mainstream throat radius and the reducing size is smaller and smaller. The existence of microfractures reduces the threshold pressure gradient of rock. Based on the above analysis, measuring the threshold pressure gradient in the lab must be strict in simulating formation conditions, according to the mineral composition of the actual formation water, simulated water is prepared, thus the measured results have practical significance.
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