深水钻井溢流井控期间水合物生成主控因素

目前多数学者都是基于热力学特征进行水合物生成的判断,但更准确的判断需要考虑分子动力学的特征。井筒中水合物形成的速度较慢,即使达到了水合物形成的热力学条件,还需要经过水合物的成核、生长2个过程。基于深水钻井溢流井控期间井筒多相流动规律,依据水合物热力学和动力学特征,结合水合物膜微孔板理论,对溢流井控期间循环、关井和压井期间水合物的生成机理进行了研究,并分析了不同流型对水合物生成的影响。研究结果表明,深水钻井溢流发生时,循环期间井口安装有节流装置不会生成水合物;关井期间泡状流情况下不会形成水合物堵塞,段塞流情况下井口处可能会形成水合物堵塞;压井期间水合物生成不会对井筒产生较大危害。

Main control factor of hydrate generation during overflow well control period of deepwater drilling

At present, most scholars judge the hydrate generation based on the thermodynamic characteristics. However, in order to make a more accurate judgment, the characteristics of molecular dynamics should be considered. The hydrate formation in the wellhole is relatively slow. Even if the thermodynamic conditions for hydrate formation are met, it is inevitable to go through the hydrate nucleation and growth processes. Based on the wellhole multi-phase flow law during the overflow well control period of deepwater drilling, characteristics of thermodynamics and dynamics of hydrate, as well as micro-pore plate theory of hydrate membrane, this paper has researched the hydrate generation mechanism in the circulation, well shut-in and well killing during the overflow well control period, and analyzed the effects of different flow patterns on the hydrate generation. According to the research results, when the deepwater drilling overflow occurs, no hydrate will be generated if the throttle device is installed at the wellhead during the circulation period; during the well shut-in period, no hydrate blocking will be formed under bubble flow conditions, but formed at the wellhead under the slug flow conditions; during the well killing period, the hydrate generation will not pose great hazards to the wellhole.