溢流关井水击压力数学模型研究

STUDY ON MATHEMATICAL MODEL FOR SHUT-IN SURGE PRESSURE CALCULATION AFTER WELL KICKS

溢流关井水击压力的大小直接决定了现场是采用“软关井”、“半软关井”,还是“硬关井”的关井方式。从溢流关井实际情况出发,应用质量守恒原理、牛顿第二定律建立了气液两相流的溢流关井水击压力数学模型,采用基于特征线法的有限差分法求解数学模型,同时编制了相应的计算机程序并进行了实例计算。计算表明:①所建立的数学模型,适用于“软”、“半软”、“硬”关井的水击压力计算;②“硬关井”、“半软关井”、“软关井”井内水击压力逐渐减小;③井内压力波动由井口到井底逐渐减小,井内为气液两相流时产生的压力比单相流更小。为了便于油气田应用,建议在瞬态模型的稳态化方面开展进一步的研究。

The magnitude of surge pressure produced upon shut-in after the well kicks directly decides which shut-in method to be used, soft shut-in, half soft shut-in, or hard shut-in. The mathematical model for shut-in surge pressure of an overflowing well with both gas and liquid has been set up based on mass conservation law and Newton second law. The finite difference method based on characteristics method has been used to solve this mathematical model, and the corresponding program has been compiled, and example calculations are given herein. The calculation shows: ① the model applies to the calculation of surge pressure after soft shut-in, half soft shut-in and hard shut-in; ② in the order of soft shut-in, half soft shut-in and hard shut-in, the surge pressure will decrease; ③ the surge pressure will decrease from wellhead to bottom hole, and the surge pressure produced in a well with gas/liquid phases is smaller than that in a well with only one single phase. To facilitate the application at well sites, it is recommended to conduct further study on mesomeric conversion of the transient model.