摘要
气井环空持续压力会带来生产安全隐患,而气体泄漏是引起井口环空持续压力的原因之一。鉴于此,考虑环空内液体的压缩性,基于气体等温达西渗流理论和PVT方程,分析了气体通过水泥环和完井液柱向上流动并形成环空压力的过程,建立了套管环空压力解析模型。对典型带压井的现场测试数据进行拟合与分析,得到了环空压力上升速度、气体流量及相关参数,验证了模型的有效性。分析结果表明:影响环空压力上升的因素有水泥环综合渗透系数、地层压力、环空中不同介质的高度、井筒温度分布及环空液体压缩性等,拟合得到的未知参数对准确度影响很小。研究结果实现了对现场环空压力测试数据的定量分析和环空压力的预测,为现场采取措施治理环空压力提供了依据。
Gas wells with sustained casing pressure （ SCP ） in annular threatens operational safely. One of the major causes of SCP is gas leakage through casing annulus. In view of this, considering the annular fluid compressi-bility, based on principles of gas isothermal Darcy seepage and PVT state equation, the casing pressure buildup due to reservoir gas migrating upward through cement sheath and completion fluid column and accumulating at the top of casing annulus has been analyzed. An analytical model for casing pressure buildup has been established. Model validation has been conducted through parameters fitting with field testing data collected from typical wells with SCP. The annular pressure buildup rate, gas influx rate and other related parameters are obtained. The analysis results show that, factors affecting annular pressure buildup include comprehensive permeability coefficient of ce-ment sheath, formation pressure, heights of different medium in casing annular, wellbore temperature distribution and compressibility of annular liquid. The unknown parameters derived from fitting have litde effect on the predic-tion accuracy. The study results have achieved quantitative analysis of the field testing data and annular pressure prediction, which provide bases for SCP management.
出处
《石油机械》
2017年第9期32-36,79,共6页
China Petroleum Machinery
基金
中国石油集团公司课题"储气库优快钻完井技术与装备研究"(2015E-4003)
关键词
环空压力
气体泄漏
压力预测
解析模型
不确定性分析
annular pressure
gas leakage
pressure prediction
analytical model
uncertainty analysis
