摘要
裸眼分段压裂是开采低渗透油气藏的主要方式,投球滑套的密封性直接决定了水平井分段压裂的成败。在一定范围内,投球滑套的密封性和球座与压裂球的接触压力、接触面积成正比。当接触压力过大时,球座与压裂球的接触面易被压溃,造成密封失效。为了避免接触压力过大造成的密封失效,本文分别对球座与压裂球接触面为锥面、弧面的两种情况进行研究,推出了锥面球座和弧面球座最大接触压力的理论公式。并通过ABAQUS有限元软件对不同锥角的锥面球座和不同曲率半径的弧面球座进行静力分析,得到了如下结论:(1)锥面球座在有效坐封和压裂球顺利反排的条件(16.7°(27)?(27)18.3°)下,锥角越小,最大接触压力和Mises应力越小;(2)弧面球座的最大接触压力小于锥面球座,且曲率半径越小,最大接触压力和Mises应力越小,当曲率半径等于压裂球半径时,达到最小值;(3)当压裂液压力超过70MPa时,应采用弧面球座。故在水平井分段压裂液压力过大时,为确保投球滑套的有效密封,应将球座与压裂球的接触面改为弧面。
Open hole staged fracturing is the main way of exploitation of low permeability reservoirs mining, and the sealing properties of ball actuated sliding sleeve are essential to the success of horizontal wells. Within a certain range, sealing properties of ball-actuated sliding sleeve are proportional to the contact pressure and contact area of fracturing balls and ball seats. When the contact pressure is too large, the contact surfaces are easily to be crushed, result in the seal failure. To solve this problem, theoretical model of cones' and cambers' maximum contact pressure within the discharge of fracturing balls and the seats sealing is introduced. Simultaneously, static analysis on the cones and cambers is achieved by means of finite element method. The following conclusions are drawn:(1) under the condition of effective setting and successful flowback(16.7°(27)?(27) 18.3°), the smaller the cone angle is, the smaller the maximum contact pressure and the Mises stress will be.(2)The maximum contact pressure of curve ball seat is less than that of the cone ball seat, and the smaller radius of curvature is, the smaller the maximum contact pressure and the Mises stress will be. When radius of curvature is equal to the radius of the fracturing balls, the maximum contact pressure reaches the minimum value. Thus the contact surfaces of ball seats should be designed to be cambered surfaces, which may avoid the crushing of contact surfaces, and enhances the sealing properties of ball actuated sliding sleeve.
出处
《应用力学学报》
CSCD
北大核心
2017年第6期1134-1139,共6页
Chinese Journal of Applied Mechanics
基金
国家973项目(2014CB239205)
关键词
投球滑套
密封
最大接触压力
球座
接触面
弧面
ball-actuated sleeve
sealing
the maximum contact stress
contact surfaces
curve ball seat
cone ball seat
