井喷失控井天然气喷量测定计算与实验研究

钻井过程中突发的天然气井喷事故会造成很大的环境危害和经济损失,准确测定井喷失控时气井产气量便成为制定抢险救援方案的一项重要工作。为此,针对天然气喷流行为特点,通过对天然气喷流流动状态的分析,研究轴对称层流喷流燃烧火焰的速度分布,利用气体伯努利方程分析气井产气量与喷流火焰高度之间的关系,对轴对称层流状态下的失控井喷量进行数值计算,完成了失控井喷量测定计算软件的编制;然后,根据实验测试数据,对比分析软件计算结果与实验测试结果,对计算软件进行了修正。结论认为:(1)当喷口形状一定时,气井产气量与喷流火焰高度呈正比关系,与气体运动黏度、化学计量比因子、氧气浓度呈反比关系;(2)修正后的计算软件计算结果与实际测试结果之间的误差在允许范围内且能够自动生成报表。该研究成果可为生产现场科学、安全的抢险救援方案的制定提供有效的分析技术手段,对失控井抢险救援工作具有实际意义。

Estimation of gas blowout volume in wells with uncontrolled blowout and laboratory studies

Gas blowout occurred during drilling may cause catastrophic environmental hazards and economic losses. It is thus one of the important tasks to accurately determine the gas blowout volume so that an effective rescue plan can be worked out in case of gas blowout. In this paper, a numerical method for estimating the gas blowout volume was presented based on the Bernoulli Equation and the corresponding software was programmed. In the process of numerical estimation, the velocity distribution of the blowout flame characterized by the axisymmetric laminar flow was investigated through an analysis of the dynamic flowing features of the gas gusher, and the relationship between the gas production of a well and the height of the blowout flame was then analyzed with the Bernoulli Equation to obtain the numerical results of the gas blowout volume. The results were then compared with those laboratory measurements, and the software was revised based on the comparisons. Some conclusions were drawn. First, when the spout shape of a gusher is constant, the gas production is proportional to the height of the blowout flame, and inversely proportional to the gas kinematic viscosity, the stoichiometric ratio factor and the oxygen concentration. Second, the errors between the results estimated using the revised software and the laboratory measurements are within the allowable range, and the software can automatically generate a report. In a word, the method and software presented in this paper can be an effective technique for preparing a sound and safe rescue plan in case of gas blowout, and is of great significance in relieving the hazards of a well with uncontrolled blowout.