Discussion of water hammer and measure to reduce water hammer pressure about hard shut-in

The Engineering importance to solution water hammer of hard shut-in has been obtained from comparing the advantages and disadvantages of all sorts of shut-in.the harmer of water pressure is not ignorable,and must take steps to avoid of it.The propagation speed calculating formula of water hammer pressure wave has been conducted based on the analysis of water hammer pressure wave speed of three-phase flow(gas,liquid,solid) in the hole,and calculated of it combined with control equation.Finally,it is put forward the method by install an air storage tank to control water hammer pressure at well head after analysis various methods of reducing water hammer pressure.The water harmer theoretical research of install air tank and without install shows that the water hammer pressure can be controlled efficiently by install air tank at wellhead,it can provide direction for oilfield drilling.