Novel technical method discussion on chemical water shut-off for gas wells

Water production from gas wells affects gas production. Though water shut-off is an effective method to cure water production on gas wells, the research and development on water shut-off technique has little progress, because of difficulty and risk of the treating operation, and it still locates at indoor research stage. The paper firstly analyzed the reason of high difficulty and high risk of gas well water shut-off, which is the demand of selective water shut-off treatment. Furthermore, based on the absorbing and referencing of the current research progress at home and abroad, from the view point of water shut-off principles, three novel types of water shut-off methods are formed. The first principle is that the water shut-off agent itself has gas-water selection capacity after injected into reservoirs; the second one is that the agent changes wettability of rock surface into more hydrophobic after getting into water beard gas formations, resulting in gas relative permeability increase and water relative permeability decrease; the third one is that the agent has some physical or chemical reactions when contacting water, such as expansion, assembling, or precipitation, to plug water flow, but no reaction when contacting gas. Furthermore, the paper proposed an integrated water treatment method from the whole gas reservoir point of view.