Force Analysis Of Injection String In Horizontal Well

Currently, the water flooding is widely used in the field for the sake of stable production and high production. With the widely use of horizontal well, horizontal injectors is becoming more and more common. In water injection, injection string in horizontal well will suffer internal pressure, external pressure, axial force of column, support force from the reaction of the sidewall, viscous friction from the fluid, etc. Under such circumstance, the string in borehole can be balanced in three circumstance: steady state, sinusoidal buckling and spiral buckling. Under the different pressure, temperature and stress condition, injection string in borehole often transform from one cirumstance to another. Such transition often cause obvious string deformation and result in sealingfailure and mechanical failings. These will result serious accident and cause great ecnomical loss. In order to avoid such fault, we need to learn string mechanism of in different cirumstances, select the appropriate parameters in designing string. Therefore, the stability and buckling, friction and load transfer, stress and deformation of mechanical problems of the injection string in different borehole has been one of the hottest research topics of the oilfield engineers and scholars. This paper analysed friction force, internal and external pressure from the fluid, viscous friction, hole deviation angle and other factors. Based on these analyses, built up basic differential equation and mathematical model of injection string under different circumstance in 3D crooked hole, built up hydraulics model and the fluid temperature's impact on string strain model. Through comprehensive analysis and calculation of the model, provide the engineers help in analysing injection string status, designing downhole tool column and make proper operation choice.