Threshold pressure gradient analysis for low mobility reservoir

The reservoir has problems of high threshold pressure gradient which makes reservoir fluid seepage flow disobey Darcy's law.Bubble method threshold pressure gradient tested and single-phase seepage flow experiments have been done whose cores come from a low mobility reservoir of oilfield,which lies in the eastern of China.The results showed that the seepage flow of low mobility reservoir has threshold pressure gradient and nonlinear seepage flow feature.The lower the mobility is,the higher the threshold pressure gradient is.The threshold pressure gradient has high relativity power correlation with mobility.An equation is also obtained to calculate the threshold pressure gradient in nonlinear seepage flow by analyzing to the data got form the single-phase seepage flow experiments.Analyzing to the nonlinear seepage flow features,minimum threshold pressure gradient and pseudo-threshold pressure gradient were obtained.Function of relation between threshold pressure gradient and displacement pressure gradient was also proposed.Based on mathematic expression for the area of nonlinear seepage flow,the lower mobility is,the wider nonlinear seepage flow area is.Through the research of low mobility reservoir threshold pressure gradient can provide relative basis for its exploitation.