Study On Parameter Optimization Method Of Water Control Fracturing Technology For Low Permeability Gas Reservoirs

The low permeability gas reservoir has the characters of poor property, low productivity. They can be developed and utilized economically only after fractured. However the fracture produced by fracturing provides a channel for water, which causes a sharp rise in water production. At present, water control fracturing fluid used by RPM is widely used, at the same time, the mathematical model and parameter optimization developed quickly. However, present model cannot be used in gas reservoirs especially in low permeation gas reservoirs. Through optimization on the water control fracturing process in gas reservoir, provided technical support for field application.Builded water control fracturing process optimization model about low permeability gas reservoir based on two phase flow model about fractured gas well. At the same time, consided on RPM aborsoption, filtration and so on. Based on the model, compiled the optimization software of water control fracturing process in low permeability gas reservoir. Analyzed the influence on gas well productivity which caused by the injection volume, filtration resistance and fuild resistance coefficient. The result shows that the water control fracturing fluid volume in bedrock is greatly bigger than the fuild in fracture; the fracture will be filled effectively when the water control fracturing fuild volume is three or four times than the fracture size; the standardization fuild resistance ratio depends on The RPM adsorption layer thickness.Analysized and studied how water control fracturing fluid standardization ratio, filtration ratio, filtration resistance ratio and filtration volume effect the gas-water relative permeability. At the same time, we studied the effective time about water control fracturing fluid. As water control fracturing fluid standardization ratio, filtration ratio, filtration resistance ratio and filtration volume increases, the degree of water phase and gas phase relative permeability decline all increase. But after each parameter increases to a certain value, the increase is not obvious. So there is an optimum value for each parameter. The result shows that based on the basic data, when the water control fracturing fluid resistance ratio is 5, the filtration rate is 0.5, the filtration distance ratio is 0.6, the injection volume is 30 to 40 m3, the water control effective time of fracturing fluid is about 300 days.At the same time, simulated water control fracturing process in low permeability gas reservoir and studied the sensitivities of the fracture parameters based on Eclipse. The result shows that the water production per day increases with the increase of fracture length, fracture flow capacity. The water production after water control is much less than just fractured, at the same time, the gas production basically keep stable. Compared the water production and gas production which used water control fractured or not, the results show that the after water control fractured the water production decreases greatly and the gas production keep stable. Through indoor simulation, based on the data of Su 255 well, recommended the volume of RPM is 30 m3. It is forecasted that the water production per day is 0.1m3/d, the gas production per day is 28969 m3/d. After fractured, the water production per day is 0.0m3/d, the gas production per day is 29770 m3/d, the error between them is less than 3%. Through whichwe know that the model and the parameter sensitivity are effective.