Heavy oil reservoirs feature in high viscosity

non-Darcy flow

and the existence of start-up pressure.According to the percolation characteristics of heavy oil reservoir

a reasonable method for measuring the start-up pressure was designed.The start-up pressure gradient of oil phase and the relationships between velocity and pressure gradient under irreducible water saturation was studied through various percolation experiments at different viscosity

permeability and temperatures conditions with the natural cores from Xinjiang oilfield.The experimental formulas of start-up pressure gradient

velocity-differential pressure curve parameters

mud logging-derived permeability

and fluid viscosity were established through experimental data regression.These experiments indicate that the start-up pressure of heavy oil reservoir can be determined rapidly and accurately with the expe-rimental method.The influences of oil viscosity on start-up pressure gradient are greater than that of reservoir physical properties.The start-up pressure gradient and velocity-pressure curve parameters are well correlated with the ratio of mud logging-derived permeability to fluid viscosity.