To effectively solve the safety problems brought by the variation of internal-external pressures on tube string in the production-injection process of underground gas storage,according to the thermodynamical and heat-transfer theories and aiming at the characteristics of fluctuations in temperature and pressure during the injection-production process of tube string in underground gas storage wells,two situations of annulus space filling with protection fluid and nitrogen column were analyzed,created the internal-external pressure equilibrium models of tube string in gas storage,and analytically calculated the internal-external pressures and the variations of tube string under two kinds of models,respectively.Meanwhile,the optimal combination chart of nitrogen column length and packer running depth was developed by focusing on the research on the optimal length of nitrogen column in annulus space.The research results show that under the same conditions,annulus nitrogen injection can reduce the annulus pressure by 50％-90％ in the injection-production process,and the optimal length of nitrogen column is 1/20-1/15 of the packer running depth.The longer the length of nitrogen column is,the lower the value of annulus pressure will be.The analysis on the sensibility of fluid temperature and pressure in oil tube indicates the prominent influence of temperature on annulus pressure variation.The reasonable length of nitrogen column injected in tube-casing annulus can prevent the tube string destruction of gas storage and the packer failure effectively.

本文通过调研当前油气田开发分层注水管柱工艺现状,对目前分层注水工艺的管柱类型和存在的问题进行分析,针对目前注水井管柱存在的屈曲、断裂、封隔器失效等众多安全问题,建立了三维注水井管柱轴侧向力耦合分析模型.研制出分层注水井管柱受力分析软件,用以分析注水管柱的受力和变形,进行强度校核,能够对管柱状态进行准确、及时判断,来指导施工油管柱的设计和分层注水工作参数的合理选择,避免管柱失效事故的发生,并给出了实例.

压裂过程中采用插管封隔器与配套的插管密封总成、打捞器一同使用,适用于层位封堵、分层开采等多种作业,工作时效长,操作简单,节约成本.本文针对在压裂环境下存在封隔器失效、管柱屈曲等问题,利用油气水井管杆柱受力分析优化设计软件(简称StrPAD)对插管封隔器压裂管柱进行力学分析和校核,满足压裂安全施工的需要.

油气水井管杆柱受力分析优化设计软件(以下简称StrPAD)是一款集油气水井三维井眼轨迹描述、管柱结构图绘制、井筒温度压力场计算、管柱各种复杂工况下力学分析以及工具通过能力计算、管柱安全分析与校核等为一体的综合分析模拟软件,软件各个模块具有很强的可操作性,能够满足客户的多种需求.本文通过总结国内外各种管柱力学分析软件的优缺点,立足于油田现场的业务需求,全面阐述StrPAD应具备的功能,从三维井眼轨迹描述、工艺管柱设计与绘制、管柱力学分析、管柱安全分析与校核四个方面进行软件的功能设计.

为了提高压裂施工成功率及措施有效率,开展节点分析设计,从压裂施工前的裂缝规模、泵注程序及管柱优化设计,到施工过程中的温压计算、施工参数可视化分析,直至施工结束后压裂液返排制度优化及产能预测.通过以上内容的研究,编制了油气井压裂分析设计预测一体化系统(简称StimPAD),该软件采用国际上先进的压裂设计理论,提供多种井型、多种储层类型及多种压裂工艺的计算模型,能够实现全面而准确的压裂分析、设计及预测.

本文主要针对连续油管环空压裂过程中的生产套管的受力进行了分析,综合考虑管柱重力、流体浮力、摩阻效应力等,通过建立三维管柱轴侧向力力学耦合模型,计算套管在施工过程中的轴向力,对环空流动压力损失进行了修正,计算环空压力、套管外压力随井深分布,利用第四强度理论对套管进行抗拉、抗内压校核,并且给出了算例.

水平井滑套分段压裂过程中油管柱处于高温高压的环境当中,很可能造成管柱严重的弯曲变形、本体拉断、鼓胀等事故,有必要对水平井滑套分段压裂过程中的油管柱受力进行分析与校核.综合考虑压裂液注入引起管柱温度发生变化、压裂液流动压力损失、管柱重力、流体浮力等,建立三维管柱轴侧向力耦合模型,计算油管在施工过程中的轴向力沿井深的分布,计算油管内压力随井深分布,利用第四强度理论对油管进行抗拉、抗内压校核,使之满足施工过程中的强度要求,并且给出了算例.

本文针对环空压裂工艺特点,考虑温度压力场对压裂管柱的影响,采用轴侧向力学耦合模型,对环空压裂的管柱进行力学分析及连续油管安全校核,现场应用表明,对压裂施工的具有较好的指导作用.