Abstract: High-rate gravel-packing sand-preventing technology is an effective sand-control measure to serious sand oil/gas wells at present.The size of gravel,the ratio of sand to sand-carrying fluid,the flow rate of sand-carrying fluid,the viscosity of sand-carry fluid,the parameters of screen pipe are all the important factors determining the success or failure of the technology and influence the result of sand prevention.The characteristics of formation sand invading into gravel packing zone and the method of calculation the pressure drop of gravel packing zone are analyzed first to optimize operation parameters and enhance operation effect,and the sand preventing effect of gravel and its effect on productivity are evaluated.Then a comprehensive method to evaluate gravel size is developed to select the optimal size of gravels.An approach to calculating minimum critical pumping rate,if given a ratio of sand to sand-carrying fluid and a low-rate sand-carrying fluid,is developed.It can be used for the optimization design of the operation parameters.At last,the design of the size of wrapping liners and the structure of strings is studied,as well as a set of theories and methods for the design of high-rate gravel-packing parameters are proposed.The design results fulfill the sand-preventing requirement and lead to good sand-preventing results.