Study On The Water Jet Perforating Technique

Practice for the development of oilfield exploitation of the world indicates that the water jet perforation is the optimal method for low permeability reservoir. There are two technical modes of water jet perforation, one is flushing cannula and cutting rock with high pressure water jet, the other is drilling cannula and radial broaching with water jet. The former has been mature, its pressure is too high (over 70 MPa) to work safely and the required intensity of oil tube is very high. The latter improves performance of the first one. It decreases the pressure of water jet system and enhances the safety and reliability. Nozzle is the key factor of improving the energy-using ratio and influences the performance of water jet obviously. Therefore it is meaningful to study, optimize geometrical shape of nozzle and construct the relation between nozzle structure and dynamical performance. The work of this paper is as follows:At first hydromechanical parameters are analyzed by the basic theory of water jet. The parameters include hydro-feature, position, hydro-power and hit power of water jet. Primary structure is determined by analyzing hydromechanical parameters of nozzle and theoretical foundation for the streamline parameter of nozzle is presented.The second numerical optimal model of the streamline parameter of nozzle is built up by analyzed result. The normal k-s model is applied by means of research for numeric simulation of water jet. The parameters are optimized by ANSYS/FLOTRAN CFD and the simulation result is obtained.The last drilling experiment is performed to testify the rock breaking capability of nozzle. That water jet pressure is 25MPa and flux is 40L/min are experimental condition. Experiment result shows that the design meet the requirement.