Abstract: In view of the problem that the pressure is difficult to reach a steady state and the test duration is long when measuring gas-water seepage under the condition of movable water, a experimental method for evaluating stress sensitivity under high temperature, high-pressure and gas-water seepage was proposed in this paper. Capacitance method was introduced to control core water saturation with liquid meter, adjust gas-water circulating flow with peristaltic pump to obtain stress sensitivity data, then the effect of movable water on reservoir stress sensitivity was analyzed. This method only breaks away from the restrictions on independent adjustment of gas-water proportion at the inlet and joint control with back pressure valve, but also provides more technologies for movable water control in gas-water seepage. The results showed that the stress sensitivity of reservoirs with movable water was much stronger than that of dry cores and reservoirs with irreducible water; with the continuous increase in core water saturation, the reservoir stress sensitivity continued to increase; the better the physical properties of the core, the smaller the effect of movable water on stress sensitivity; a productivity model under movable water conditions was established with consideration of stress sensitivity, and it was found that the higher the reservoir water saturation, the greater the effect of stress sensitivity on gas well productivity. The experimental study has an important guiding role in the seepage mechanism and productivity evaluation of water-bearing gas reservoirs.

Key words: movable water, tight gas reservoir, stress sensitivity, water saturation, gas well productivity