元坝高含硫气井油套环空正常起压规律

Normal annular pressure regularity in“A”annulus for high sulphur gas wells in Yuanba gas field

对于元坝这种高含硫并于近期大幅度提产的气井来讲,温度效应引起的环空压力也是一类不容忽视的井筒安全威胁。首先结合元坝气井产水并且产气中含非烃成分的实际生产情况,建立了考虑非烃校正的气液两相流井筒温度、压力计算模型和温度效应引起环空压力预测模型,通过实例计算和参数敏感性分析获得了油套环空正常起压规律,并提出了相应的环空压力控制措施。然后通过不同产气量和产水量情形的模拟计算,建立了油套环空起压类型判断图版,并将该图版进行了现场应用,实现了元坝3口重点井的起压类型判断。结果表明:降低环空流体热膨胀系数、提高环空流体等温压缩系数和油套管变形系数都是控制环空压力的有效方法;投产初期预留一定环空气腔高度有利于降低环空压力。

For high Sulphur gas wells in Yuanba gas field that have a substantial increase in production,the annular pressure caused by thermal expansion effects is a kind of wellbore safety threats which cannot be ignored.Combined with the actual production situation,a wellbore temperature-pressure calculation model of gas-liquid twophase considering nonhydrocarbon correction and a prediction model of annular pressure caused by thermal expansion effects were firstly established.The normal annular pressure regularity was obtained through the example calculation and the sensitivity analysis of influencing parameters.Meanwhile,corresponding annular pressure control measures were put forward.The judgment chart of annular pressure types in the“A”annulus was established through a large number of simulation calculation with different gas production rate and water production rate.Then,the judgment chart was applied to the field,which realizes the annular pressure type judgment of three key wells in Yuanba gas field.The results show that to reduce the thermal expansion coefficient of annular fluid,to improve the isothermal compression coefficient of annular fluid and to improve the deformation coefficient of casing,are all the effective methods to control the annular pressure caused by thermal expansion effects.To reserve a part of the annular space at the beginning of production is also beneficial to reduce the annular pressure caused by thermal expansion effects.