Experimental Study on the Threshold Pressure Gradient in Low Permeability Heavy Oil Reservoirs

The threshold pressure gradient is one of key parameters for the development of low permeability heavy oil reservoirs. A new set of device for the measurement of the threshold pressure gradient was designed. The effect of permeability, fluid viscosity on the threshold pressure gradient of low permeability heavy oil reservoirs was studied experimentally. The theoretical chart of threshold pressure gradient vs. pseudo-mobility was drawn on the basis of experimental results. Experiments show that the threshold pressure gradient of low permeability heavy oil reservoirs is very large, and affected by permeability and fluid viscosity; the threshold pressure gradient increases with the decrease of permeability and fluid viscosity, and it decreases with the increase of the pseudo-mobility. The threshold pressure gradient for a typical low permeability heavy oil reservoir can be obtained by the theoretical chart at a certain pseudo-mobility. This is very important for the development of low permeability heavy oil reservoirs.