侧斜井剖面优化设计方法

Optimization Design Method of Sidetracking Well Profile

A油田套损井累计占生产井数的15.1%,为了不影响原来的井网部署和开发方案,减少钻井占地面积及成本,可采用侧斜工艺技术进行套损井的修复。综合考虑A油田老井网的特点,结合侧斜井现场施工的实践,确定了侧斜井剖面设计的井身质量的一般原则:全井井眼曲率小于1.5°/30m,最大井斜角不超过3°,设计水平位移不能大于30m;侧斜井的井身剖面选用"直井段-侧斜段-稳斜段-降斜段",将最大井斜角定为已知,设计方位与原井眼方位相反。指定井身剖面设计方程组的4个参数为已知设计参数,求出方程的解析解,并利用该解析解研究了最大井斜角和井眼长度随造斜点的变化规律,提出了以造斜点为优选变量的优化设计算法。实际算例表明,该优化设计方法可以使用很少的计算量,快速求出满足井身质量要求的最优设计参数和最优设计剖面。

Casing damage wells in oilfield A account for 15.1 percent of the number of producing wells.The casing damage wells may be repaired by side tracking technology in order to remain well pattern and development program before and reduce footprint area and cost of drilling.Considering the features of old well pattern in oilfield A and the practice of field operation by the sidetracking wells ,normal principle of weUbore quality in profile design of the sidetracking wells is made.That is borehole curvature is less than 1.5°/30m, maximum hole deviation angle is less than 3° and designed horizontal shift is less than 30m.Wellbore profile of the sidetracking wells is from straight section,side tracking section to angle maintain section and angle drop section.The maximum hole deviation angle is fixed as known and designed direction is contrary to original borehole direction.Four parameters in equation set of wellbore profile design are fixed as known designed parameters.Analysis solution of the equation may be solved that may be applied to the study of the maximum hole deviation angle and change rule of borehole length along with kick off point.Optimized design algorithm is proposed taking the kick off point as the optimized variable.Actual case shows that this optimized design method may be applied to solving optimized design parameters and optimized design profile satisfied with the wellbore quality by a little calculation