Experimental Method and Its Applications of Threshold Pressure Gradient of Heavy Oil in Porous Media

According to seepage law and material balance principle of single phase fluid in porous media,a one-dimensional theoretical model of heavy oil seepage is established based on micro-compressible property and non-linear flow of heavy oil in porous media.Two experimental methods of unsteady state seepage are designed to measure the threshold pressure gradient of heavy oil in porous media.Experimental pressure with time at the inlet of porous media was matched by adjusting the threshold pressure gradient during the two processes of constant flow injection and shutting the inlet,so the threshold pressure gradient of heavy oil in porous media was calculated at different temperatures.The threshold pressure gradient of heavy oil was more precise by calculating from shutting the inlet than constant flow injection.The reason was that the experimental method of shutting the inlet of porous media only measures pressure without considering oil phase flow at the inlet of porous media.The method has advantages of easily operation,rapid stabilization and high accuracy.