Design And Optimization Of Long Lateral Horizontal Wellpath In Long-offset Distance

With growing number of structure-complicated wells in China,pursuits of higher wellpath design standard are aroused.This Paper focus on long lateral horizontal wellbore characterized by long offset distance,makes the research on wellslot layout and wellpath optimization especially in cluster horizontal wells.The paper is started by the introduction of conventional ways of slots layout in cluster wells,followed by universal wellslot layout methods in consideration of well trajectory intersection and pre-target displacement of horizontal well.It develops the ‘two step' method separated by wellsite location planning and wellhead position arrangement of single platform by using Genetic Algorithm.Secondly,with the target of drag and torque on drillpipe and casing pipe,the paper analyses how the factors of kickoff point,build-up rate,build-up/hold-on arrangement and wellpath anti-collision affect the wellpath design,and summarize the ideal parameters constraint related to wellpath optimization.Based on existing wellpath models established by former experts,this paper cites the sptial-circular-arc model to seek the calculation of optimized wellpath parameters considered by a blend of factors concluding total depth,build-up segments length,maximum build-up rate,target accuracy and relative position of wells by using Particle Swarm Optimization(PSO)algorithm.Finally,based on the wellslot arrangement and wellpath optimization methods in the research,the author complies the two related software in Visual Basic 6.0,one of which functions in wellsite location planning and wellhead position arrangement;the other one can be served in fundamental wellpath optimization,simplified anti-collision scanning,and optimized wellpath anti-collision adjustment.