Study On The Integrity Of Branch Points In Sidetracking Branch Wells

At present,the development of many oil and gas fields in China is in the middle and late stages,and most of the old wells have low production capacity or no production.How to make full use of the original wellbore and realize the recovery of single well production through sidetracking technology is essential for improving the development efficiency of oil and gas fields and reducing development costs.This article focuses on factors such as the stress around the wellbore,the angle between the branch wellbore and the main wellbore,and the orientation of the branch well.Based on the elastic theory and rock mechanics,the finite element analysis method was used to establish the branch point borehole integrity model,and the in-depth analysis and research on the mechanical characteristics of the borehole integrity of the sidetracked branch well at the branch point were conducted.Firstly,the influence of factors such as sidetracking mode and completion type of sidetracking lateral wells on the integrity of the wellbore was analyzed in detail,and the degree of integrity of the branch points of sidetracking lateral wells was analyzed through risk assessment,and the open hole sidetracking was obtained The completeness at the branch point of the lateral drilling branch well under the first-level completion conditions is the worst.Secondly,considering the factors affecting the integrity of the wellbore,the geometric model of the main wellbore and the sidetracking lateral wellbore branch points was established,the formulas for the stress distribution of the vertical well and the deviated well were deduced,and the stress at the branch point was analyzed,The calculation model of the rupture pressure and collapse pressure of the branch point is obtained.Finally,according to the calculation model,the mechanical model of branch points of three-dimensional sidetracking branch wells is established by using the finite element simulation technology.The influence of the angle between main borehole and lateral boreholeand,the azimuth of the branch well,the rock type and the well spacing on the integrity of the branch point of the sidetracked branch well is analyzed.As the inclination angle of the lateral well of the lateral drilling lateral well increases,the maximum stress value at the lateral point of the lateral drilling lateral well decreases.When the azimuth angle of the lateral well is 0°,the stress value at the branch point of the lateral drilling lateral well is the smallest,and it reaches the maximum when the lateral azimuth angle of the lateral drilling lateral well reaches 90°.As the drilling depth continues to increase,the distance between the main borehole of the lateral well and the lateral borehole gradually increases,and the stress concentration in the lateral borehole of the lateral borehole gradually weakens.The research results in this paper can not only guide the actual construction operations of sidetracking lateral wells,but also support the extension of the production cycle of sidetracking lateral wells,and have practical significance for the efficient and safe development of oil and gas.