Computation Analysis Of Surge Pressure On Casing Running In Highly-deviated Wells

As the exploration of oil reservoir develops in depth and in quantity,the highly-deviated wells are increasingly growing in number.The characteristics of highly-deviated wells include complicated well path,large deviation angle and long open hole,and hard wellbore cleaning,which bring many challenges to the subsequent work.Inaccurate prediction to the surge pressure on casing running in highly-deviated wells can cause complex condition and accidents such as wellbore instability and leakage and so on.Which can bring about irregular wellbore diameter and poor quality in cementing operation,and affect the subsequent production and the life of oil and gas well.So,it has important and practical significance to study the computation method of surge pressure on casing running in highly-deviated wells.This paper analyzes the cause of the surge pressure on casing running and the dynamic mechanism of pressure wave transmission in drilling fluid,and builds a velocity transmission model that pressure wave spreads in drilling fluid.This paper proposes equivalent diameter to simplify annulus diameter by comparing the pipe flow with annular flow,and builds the calculation model of wall shear stress in flow channel in the process of casing running.This paper analyzes the flow state of drilling fluid on casing running in highly-deviated wells based on the theory of elastic tube-compressible fluid,and builds the two-dimensional transient surge pressure calculation model on casing running in highly-deviated wells.Based on the two-dimensional model,this paper builds the three-dimensional transient surge pressure calculation model on casing running in highly-deviated wells by taken the deviation angle and azimuth angle into consideration.And the continuity equation and the motion equation of the two-dimensional and three-dimensional models to calculate surge pressure are deduced and the Mac Cormack numerical solutions is given to be conveniently programmed.Based on the transient surge pressure calculation model on casing running in highly-deviated wells,the author develops the software of surge pressure calculation on casing running in highly-deviated wells under the development environment of VB.With the software,this paper gives the prediction of surge pressure in a development well,and analyzes the various factors that influences the surge pressure on casing running in highly-deviated wells and the law of various factors to surge pressure,which lays a theoretical foundation for casing running safely in highly-deviated wells.