裂缝性地层井壁稳定研究

Study on borehole stability of fissured stratum

通过对裂缝性地层井壁稳定开展研究,利用离散元模型与有限元模型对井壁井眼稳定进行分析,得出利用离散元方法是基于剪切破坏而没有考虑岩块松散(井眼扩大),虽然大多数情况下坍塌确实是有剪切破坏引起的,但是在高压差作用下,井眼扩大也会造成很严重的问题。而利用有限元模型研究裂缝性地层井壁失稳和井眼膨胀。但是因为假设条件的不同,计算误差也偏大。但如果能合理的选取适合的边界条件,还是能满足工程计算的需要。

On the base of study on stable borehole of fissured stratum,discrete element model and finite element model were used to analyse borehole stability.Study results show that discrete element method is based on shear failure without concerning rock loose,ignoring the effect of borehole enlargement on the high differential pressure.Compare with the discrete element method,in order to meet the engineering calculation need,the finite element model can be used to analyse the borehole wall instability and the borehole expansion of fissured stratum with suitable boundary conditions.