Physical simulation of water influx mechanism in fractured gas reservoirs

To study the water invasion performance and the influencing factors in the fractured gas reservoirs and provide a scientific basis for the design of development plan of the gas reservoirs, three kinds of full diameter long-core combination models were designed and an experimental system of the water invasion performance in fractured gas reservoirs was established. Three different models were employed in the physical simulation of the different bottom waters, productions and pressures in gas reservoirs, and their water invasion mechanisms in different conditions were analyzed. The results show that the size of fracture permeability influences water coning rate. The bigger permeability is, the greater water coning rate would be. Thus, it can reduce gas ultimate recovery. Bottom-water has a great effect upon fractured gas reservoirs, but gas well has little change if bottom-water size exceeded a certain extent. The higher gas pressure in fractured bottom-water gas reservoirs is, the greater coning rate would be. Thus, the higher the water-gas rate is, the lower gas ultimate recovery would be. Single well production influences water coning rate. With the increase of the single well production, water coning rate strengthens, then gas recovery decreases but there is little change.