摘要
深水井生产过程中,当地层高温流体流向井口时,由于温差的存在,会通过井筒向地层传递热量,破坏水合物地层的原始温度和压力环境,诱发水合物分解并产生大量甲烷气,导致突增的附加高压直接作用于水泥环,甚至会引发地层失稳、海底滑坡等灾害,严重威胁深水井的井筒完整性。鉴于此,基于传热学理论建立了井筒温度场模型,计算水泥环第二胶结面温度,同时结合渗流理论、能量和物质守恒定律及水合物分解动力学建立了水合物分解热传递方程,分析了水合物分解的产气量及分解距离的变化规律和影响因素,为水合物分解诱发的附加高压研究提供理论依据,进而提出深水井井筒完整性的管理措施。研究结果表明:随着天然气水合物地层不断吸收热量,与水泥环第二胶结面之间温差逐渐减小,水合物分解产气量和分解距离逐渐达到最大值;天然气水合物初始饱和度越大,水合物分解产气总量越大,但最终分解距离越小;深水井日产量越高,水合物分解产气总量与最终分解距离越大。生产中可以通过调控深水井开采制度来控制水合物分解,降低深水井生产阶段的风险。
In the production process of deep-water wells,when the high-temperature formation fluid flows to the wellhead,it may transfer heat to the formation through the wellbore as the result of temperature difference.This can destroy the original temperature and pressure environment of hydrate formations,cause hydrate decomposition,and produce a large amount of methane gas,as a result of which the sudden increase of the additional high pressure will act directly on the cement sheath,thus leading to disasters such as formation instability and submarine landslide,and seriously threatening the wellbore integrity of the deep-water wells.In view of this,the wellbore temperature field mode was established based on the heat transfer theory,and used to calculate the temperature of the second cement face of the cement sheath.Meanwhile,based on the seepage theory,the law of conservation of energy and matter,and the kinetics of hydrate decomposition,the heat transfer equation of hydrate decomposition was set up to analyze the change law and influence factors for the gas production and decomposition range of hydrate decomposition,so as to provide the theoretical basis for studying the additional high pressure induced by hydrate decomposition,thus proposing management measures for the wellbore integrity of deep-water wells.The research results show that as the natural gas hydrate formation constantly absorbs heat,the temperature difference between it and the outer wall of the cement decreases gradually,while the gas production of hydrate decomposition and decomposition range gradually hit the peak;the higher the initial saturation of natural gas hydrate is,the greater the total gas production of hydrate decomposition is,and the smaller the final decomposition range is;the higher the daily gas production of the deep-water wells is,the greater the total gas production of hydrate decomposition and the final decomposition range are,and hydrate decomposition can be controlled during production by regulating the deep-water well production
作者
张智
赵苑瑾
张喆
蔡楠
刘和兴
马传华
梁继文
Zhang Zhi;Zhao Yuanjin;Zhang Zhe;Cai Nan;Liu Hexing;Ma Chuanhua;Liang Jiwen(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Sichuan Chengdu 610500,China;Zhanjiang Branch,CNOOC China Limited,Guangdong Zhanjiang 524057,China)
出处
《石油学报》
EI
CAS
CSCD
北大核心
2022年第2期281-292,共12页
Acta Petrolei Sinica
基金
国家自然科学基金项目(No.52074234)
四川省青年科技创新研究团队专项计划项目(2020JDTD0016)
中海石油(中国)有限公司科技重大项目(CNOOC-KJ 135 ZDXM 38 ZJ 05 ZJ)资助。
关键词
深水井
天然气水合物分解
产气总量
分解距离
开采制度
deep-water well
natural gas hydrate decomposition
total gas production
decomposition distance
production system
