致密油藏多级压裂球座钻磨铣工作机理分析

Mechanism Analysis of Multi-Stage Fracturing Ball Seat Drilling and Milling in Tight Reservoirs

目前致密油藏多级压裂球座的钻磨铣工艺存在工作效率低、故障率高及使用寿命短等问题。为满足压裂球座高效、低成本钻磨铣施工需求,通过ABAQUS软件建立单磨粒磨削模型,对钻磨铣球座工作机理进行分析,重点分析磨粒前角、磨削深度和磨削速度对磨削力的影响规律。分析结果表明:磨削力随磨粒前角增大而减小,且近似可看作二项式关系,负磨粒前角可以产生更大的磨削力;磨削深度为4 mm时形成断屑,而且磨削深度越大,越易形成断屑,随着磨削深度的加深,断屑点前移,磨铣工具单圈磨削深度在4 mm左右较合适;在单磨粒正常磨削速度范围内,磨削速度对磨削力的影响不大,可以忽略,单纯改变磨铣工具转速对提高磨铣效率意义不大。研究成果对于钻除压裂球座,实现多级压裂井后期的大通径生产作业具有重要意义。

At present,the drilling and milling process of multi-stage fracturing ball seats in tight reservoirs has problems such as low work efficiency,high failure rate and short service life.To meet the requirements of high-efficiency and low-cost drilling and milling of fracturing ball seat,a single abrasive grit model is established by ABAQUS software to analyze the working process of the ball seat drilling and milling.Focuses are put on the analysis of the influence of the abrasive grit rake angle,the milling depth and the milling speed on the milling force.The analysis results show that the milling force decreases with the increase of the rake angle of the abrasive grit under approximately binomial relationship.Negative abrasive rake angle can produce larger milling force.When the milling depth is 4 mm,broken chips are formed.The greater the milling depth,the easier it is to form broken chips.With the deepening of the milling depth,the chip breaking point moves forward.The single cycle milling depth of 4 mm for the milling tool is preferable.In the range of normal milling speed,the milling speed has little effect on the milling force,which can be neglected.Simply changing the rotation speed of the milling tool is of little significance for improving the milling efficiency.The study is of great significance for the drilling of multi-stage fracturing ball seats in tight reservoirs and the production in the large-diameter multi-stage fracturing wells.