振动注水对套管、水泥环及地层影响的计算研究

为了评价振动注水对套管、水泥环及地层的影响,基于所给出的套管及水泥环在地层状态的简化力学模型和弹性力学理论,给出了套管、水泥环、地层的轴对称应力分布公式。根据套管内壁面、套管与水泥环接触壁面、水泥环与地层接触壁面存在的应力关系,推导出弹性体相接触时的应力数学模型,并对该数学模型进行求解。依据材料力学理论和振动注水的注入压力随时间变化的简化曲线进行了工况分析,选取适当参数计算出不同内压作用下套管、水泥环、地层岩石中最大应力,得出了在交变注水压力作用下套管、水泥环、地层岩石中的最大应力随注水压力变化的关系曲线。最后得出结论――振动注水所产生的脉动压力不会对套管、水泥环及地层造成损坏。

THE CALCULATING RESEARCH OF THE INFLUENCE TO CASING PIPE,CEMENT SHEATH AND FORMATION BY VIBRATED WATER INJECTION

In order to evaluate the influence of vibrated water injection to casing pipe, cement sheath and formation, the research was conducted. Based on the simplified mechanics model of casing pipe and cement sheath in layer and mechanics of elasticity, this paper provided the axi-symmetrical stress formula of casing pipe, cement sheath and layer. According to the stress relation of casing pipe inner wall, between casing pipe and cement sheath, cement sheath and stratum in flat, the mathematic model on stress and the solution was deduced, when the elastomers are contacted. On the basis of mechanics of materials and the simplified curve of water injection pressure while vibrated injection, selecting the proper parameters, this paper analyzed the working condition and calculated the maximum stresses in casing pipe, cement sheath and formation rock while alternating internal pressure and deduced the related curves between maximum stresses and alternating water injection pressure. Finally, the conclusion is that the pulse pressure caused by vibrated water injection can not damage to casing pipe, cement sheath and formation.