Study On Calculation Method Of Surge Pressure In Wellbore

Surge pressure or suction pressure often occur in the pipe trip,switching pumps and other operations,which is named Surge Pressure,excessive surge pressure will cause great damage to the well,such as blowout,borehole leakage,even the collapse of the wellbore and so on,so accurate calculation of surge pressure that generated in the drilling process has great significance for the correct guidance of field operations.This paper mainly studies the calculation method of surge pressure and the corresponding influencing factors.Based on the slot floe model,the drilling fluid rheological model is preferred.According to the real situation of the fluid flow in the wellbore,considering the corresponding boundary conditions,combined with the model of the previous study,the steady fluctuation pressure calculation method is finally established.The numerical solution is also introduced to solve the model.Field production data is used to verify this model.Combined with previous experimental data comprehensive analysis of other models,the model has a high accuracy,and the measured value of the basic error within 5%.The influence law of steady-state model influencing factors is analyzed.The fluid flow in the wellbore is a unitary flow.The control equation is established by the balance of mass conservation and force.The transient pressure control equation is established,using the characteristic line method to solve the equation.Based on the field experiment data,the comparative analysis model data,the results are basically consistent.Then the influence law of the influence factors of transient model is analyzed.In this paper,a model is established for the fluctuation pressure under the switching pump condition.The influence law of the fluctuation pressure is analyzed for the different time of the switching pump,which has certain importance for the method of switching the pump in the actual operation.