深水水平井气侵井控临界压井排量研究

Study on critical killing displacement of gas kick in deepwater horizontal wells

在深水水平开发井发生气侵后,气体极易在上翘段聚集形成气塞,如何安全高效地将聚集气体循环出井,对深水钻井井控安全至关重要。在开展不同倾角气体聚集井筒两相流动实验研究基础上,揭示了气体携出机理,阐明了压井液物性、排量对气体携出的影响规律。利用实验数据对现有漂移模型进行优选,结果表明:Bendiksen气体漂移模型在预测临界压井排量时效果较好,并引入钻井液物性无量纲参数对Bendiksen模型进行修正。修正后的新模型预测结果与不同水平倾角(8°~27°)、不同黏度(1~50 mPa·s)下实验数据匹配度较好,能够准确预测排出水平段聚集气体所需的临界压井排量。本文给出的水平段临界压井排量计算方法,可有效指导深水水平段压井设计与施工。

Gas slugs are likely to be formed in the upwarps if a gas kick should occur in deepwater horizontal wells.Circulating the gathering gas out in a safe and efficient way contributes to a smooth well control in deepwater drilling.The gas-liquid two phase flow experiment of gas gathering at various wellbore angles was conducted to reveal the mechanism of gas carrying out and illustrate the effects of physical properties and displacement of kill fluidon gas carrying out respectively.The experimental data was used to optimize the existing drift models.The results showed that the Bendiksen gas drift model was superior for predicting the critical displacement of well killing.A dimensionless parameter of physical properties for drilling fluid was introduced to modify the Bendiksen model.It showed a good fit in the prediction results of the newly-modified model and theexperimental dataat various horizontal inclined angles(8-27°)and viscosities(1-50 mPa·s).An accurate critical displacement of well killing to circulate the gathering gas out in horizontal sections could be derived from the model.The method for calculating the critical displacement of well killing in horizontal sections can effectively guide both the design and construction of deepwater horizontal well killing.