生产管柱泄漏气井油套环空起压模式对比

Comparison analysis of tubing-casing annular pressure rising pattern in gas well with production string leakage

陆努,张波,胥志雄,娄尔标,罗方伟,谢俊峰,刘洪涛,赵效锋

中国石油勘探开发研究院，北京 100083 中国石油安全环保技术研究院，北京 102206 中国石油塔里木油田分公司，新疆 库尔勒 841000 中国石油塔里木油田分公司油气工程研究院，新疆 库尔勒 841000 中国石化中原油田分公司石油工程技术研究院，河南 濮阳 457001

生产管柱泄漏是诱发气井油套环空（以下简称环空）带压的主要原因之一。为了弄清典型环空起压模式的特征和风险，文中建立了基于气体PVT性质和体积相容性原则的环空压力计算模型。研究结果表明：因浅层生产管柱泄漏，气井环空压力呈现出上升速度快、上升周期长和压力高的特点；泄漏点孔径的增加将导致泄漏速率和压力上升速度大幅增加，大孔浅层泄漏具有压力高、速度快、气体体积大的特点，风险最高，而小孔深层泄漏风险最低；同一深度泄漏点，无因次环空压力上升周期与无因次泄漏点孔径呈幂函数关系，可用于快速判断泄漏程度；根据最大允许环空压力、关井状态下的生产管柱内及环空压力分布，可确定泄漏深度阈值，防止在该深度以浅发生泄漏，从而避免环空压力超过最大允许值。

Tubing leakage is one of the main reasons to cause sustained tubing-casing annular pressure in gas wells. To compare the characteristics and risks of typical pressure rising modes, annular pressure model is built based on PVT property and volume consistence principle. The analysis shows that annular pressure caused by shallow leakage has fast rising speed, long rising period and high pressure value. The increase of leakage diameter leads to significant increase of gas leakage rate and pressure rising speed. Annular pressure caused by shallow large leakage hole is featured with high pressure value, fast rising speed and large annular gas volume, so the risk is the highest while the risk of annular pressure caused by deep small leakage hole is the lowest. Under the same leakage depth, there is power ratio relation between the dimensionless pressure rising period and dimensionless aperture, which can be used to quickly judge the leakage degree. A depth value can be determined according to the maximum allowable annular pressure, pressure distribution in production string and annulus when well is in shut-in state, so as to prevent leakage above this value and avoid annular pressure exceeding the maximum allowable value.

10.6056/dkyqt202104026