地层出砂及射孔对套管屈曲损坏的影响分析

油藏出砂后,上覆地层重力转移到套管轴向上,当轴向载荷超过套管临界屈曲载荷后,套管发生屈曲损坏。建立了考虑射孔的套管屈曲损坏有限元力学模型,旨在探讨射孔参数对出砂引起套管临界屈曲载荷的影响,从而确定合理的射孔参数,提高套管临界屈曲载荷,为预防出砂引起的套管屈曲损坏提供理论支撑。计算结果表明,在出砂严重的地层,应选择合理的射孔孔密和相位,避免选用相位180°射孔。如果出于产能考虑,必须要采用180°相位射孔,射孔孔密严禁超过44孔/m。当射孔密度大于22孔/m时,应选择90°相位射孔。

An analysis of the perforation and formation sand production on casing buckling failure

While the oil reservoir produces sand,the gravity of overlying formation transfers to the axial direction of casing.When the axial load surpasses the casing critical buckling load,casing buckling failure happens.Therefore,a finite element mechanical model of casing buckling damage with perforation considered was established.The effect of perforation parameter-related sand production on casing critical buckling load was discussed so as to determine the proper perforation parameter,improve casing critical buckling load and provide a theoretical basis for the prevention of sand production-caused casing buckling damage.The calculation result shows that in serious sand production formation,the proper perforation density and phase should be selected,avoiding selection of 180° phase perforation.With production capacity considered,180° phase perforation must be adopted;perforation density must not go beyond 44 holes per meter.When the perforation density goes beyond 22 holes per meter,90° phase perforation must be chosen.