封隔器胶筒表面形貌对密封性能影响研究

Effects of the packer rubber surface morphology on the sealing performance

水平井分段压裂是目前低渗油气藏增产的主要措施之一,压裂封隔器是分段压裂时层与层之间封隔的关键工具,其封隔性能直接影响压裂施工工艺的施工质量和成功率。由于受到深井地层高温、高压等恶劣环境的影响,封隔器胶筒坐封后与套管间的接触应力、Mises应力直接影响其封隔能力和使用寿命。本文通过改变封隔器胶筒表面圆弧半径R、圆弧顶距胶筒表面距离δ、波纹间隙ΔH等参数来研究胶筒与套管间接触应力情况,结果表明：与常规封隔器胶筒相比,改进的封隔器胶筒与套管的最大接触应力提高了1.64倍～3.97倍;圆弧半径为1.25mm,波纹间隙为0.5mm的改进胶筒Mises应力降低了约11%。这不仅保证了封隔器密封可靠性,而且降低了胶筒被撕裂的风险。表面轮廓为波纹状的封隔器胶筒可广泛运用于水平井分段压裂工艺中。

Horizontal staged fracturing is one of the main measures to increase production in low-permeability reservoir; packer is the pivotal tool of layer and layer in staged fracturing, whose performance directly affects the construction quality and the success rate. Due to working in an environment of high temperature and high pressure, contact stress and Mises stress directly affect packer capacity and service life after packer rubber sealing. The contact stress between rubber and borehole wall is investigated by changing arc radius R, apex distance δ and corrugated clearance ΔH. The results show that contact stress has been improved 3.97%, compared with conventional structure under arc radius R=1.25 mm and corrugated clearance ΔH=0.0mm, Mises stress has been reduced by 11% under arc radius R=1.25 mm and corrugated clearance ΔH=0.5mm, which not only ensure the packer seal reliability, but also reduce the risk of avulsion. Corrugated surface profile of the packer rubber has a broad prospection in horizontal staged fracturing.