Abstract: At present, gas-water relative permeability curves of gas reservoirs with high temperature and high pressure are mostly obtained by unsteady testing method. The testing device is mainly equipped with back pressure valve to control fluid pressure. However, the pressure is easy to change under high temperature and high pressure, resulting in deviation in gas-water measurement. For this reason, this paper proposed a testing device and method for unsteady gas-water relative permeability under high temperature and high pressure based on the capacitance method. The testing device was fixed a self-developed capacitance liquid meter. The experimental temperature and pressure were increased to 200.0 ℃ and 80.00 MPa, respectively. The water production rate was measured by the change of liquid volume and capacitance. An electric turbo-metering pump was used to control the fluid control and measure the gas volume. The influence of fluid pressure and oil reservoir temperature on the gas-water relative permeability curve was analyzed on the basis of experimental test data. The results showed that under the same conditions, when the experimental temperature was increased, the irreducible water saturation was lower and the gas-water co-permeation area was wider; when the experimental fluid pressure was decreased, the irreducible water saturation was higher and the relative permeability of the gas phase was lower. The study results are of great significance for guidance in the development scheme design, dynamic analysis and understanding of gas-water seepage rules of gas reservoirs with high temperature and high pressure.

Key words: gas-water relative permeability, relative permeability test, unsteady state, high temperature, high pressure, experiment, capacitance method