储气库注采管柱多周次循环交变载荷力学分析

Mechanical Analysis of Multi-cycle Cyclic Alternating Load of Injection-production String in Gas Storage

储气库是实现天然气调峰保供、高效利用的有效手段。储气库井主要以同井进行注采的方式生产,相较于常规油气藏的开发井,注采过程具有强度高、周期长、反复吞吐的特点,采用常规油气井的管柱强度设计方法不能满足储气库井的设计需要。本文开展了储气库注采管柱在多周次循环交变条件下的力学载荷分析研究,分析了注采过程主要的附加载荷作用,建立了鼓胀效应、温度效应与地层作用的力学模型,在此基础上结合管柱的自重效应,建立了考虑鼓胀、温度与地层等多种效应下的力学分析模型。以文23储气库为例开展了注采管柱的载荷力学分析计算,通过计算表明,注采管柱在注气期与采气期的不同阶段、管柱的不同深度下呈现不同的拉压载荷作用,且随着多个注采周期的时间推进,交变载荷呈累加效应。该力学分析模型的建立可为储气库注采管柱的优化设计提供数据支持。

Gas storage is an effective means to realize peak shaving,supply guarantee and efficient utilization of natural gas.Gas storage wells are mainly produced by injection and production in the same well.Compared with the development wells of conventional oil and gas reservoirs,the injection-production process has the characteristics of high intensity,long cycle,and repeated huff and puff.The string strength design method of conventional oil and gas wells cannot meet the design requirements of the gas storage wells.The mechanical load of the injection-production string in the gas storage under the condition of multi-cycle cyclic alternation has been studied,and the main additional load effects in the injection-production process have been analyzed.The mechanical models of the ballooning effect,temperature effect and formation effect have been established.On this basis,combined with the self-weight effect of the string,the mechanical analysis model considering the multiple effects of ballooning,temperature and formation has been established.Wen 23 gas storage is studied as a case.The load mechanics analysis and calculation of the injection-production string are carried out.The calculation results show that the injection-production strings present dfferent tensile and compressive loads at different stages of the gas injection period and the gas production period,and at different depths of the pipe string,and the alternating load presents a cumulative effect with the time advance of multiple injection-production cycles.The establishment of the mechanical analysis model can provide data support for the optimal design of the injection-production string in the gas storage.