Mechanical Analysis And Software Development Of Layered Water Injection String

Separate layer water injection technic is one of the efficient measures for improving oil recovery rate because it can meet the energy needs of different oil reservoirs accurately.During actual operation and production,there exist some problems such as serious abrasion of water injection tools,short service life of injection string,low success rate of injection technology.One of the important reasons for above problems is the unreasonable design of separate layer string because of inaccurate mechanic analysis.Therefore,considered general influence of hole structure and varieties of injection tools,establishing scientific mechanical analysis model of layer water injection string,studying the mechanical behavior of string accurately is an important task for improving the design rationalization level of injection string and success rate of separate layer water injection technology.The paper based on summarizing the present status of separate layer water injection technic and historical course of pipe string mechanics,considered influence of floating gravity,bending moment,contact force,friction force,internal and external pressure,hole curvature,meanwhile,considered comprehensive effect of varieties of injection tools,established three-dimension mechanical analysis model of layer water injection string.The model can simulate actual mechanical condition and apply to inclined shaft,directional well,horizontal well and other kinds of well hole.The paper studied well hole temperature field which affect mechanical property of water injection string importantly in detail.According to the basic principles of heat transfer and actual conditions,a dynamic analysis mathematical model of well hole temperature field was established.After solved by finite difference method,the model can calculate the well hole temperature after water injection,stopping injection or flushing any time dynamically.The paper also studied the effect law of water injection parameter to well temperature.According to establishing mechanical equation,the phenomenon and mechanism of layered water injection string creeping was discussed.On the basis of analysis and calculation of maximum static friction force and axial force of packer,a method of calculation on displacement of packer creeping was proposed,and an example was gave.Based on theoretical research,a general analytical software which include three-dimensional emulation,string design,mechanical analysis,results illustration and data management function was developed.The software would provide technical support for the design of separate layer water injection string and analysis of mechanical property accurately.