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基于欠平衡钻井技术的优点,油田现场使用欠平衡钻井技术钻井的数量增长很快,其优点包括钻速的提高、循环漏失和差压卡钻最小化、地层伤害减小及许多环境上的优势。在连续油管欠平衡作业过程中,通常使用气液混合物,其中两相流系统的水力计算是必不可少的。井筒水平段的几何流动形态是完全偏心环空的,需要一个真实的机械模型。对环形几何空间两相流研究很少,通常是用水力直径表示环形几何空间,使用水力直径代替环空直径来使用环形管的关系式。然而,基本的水力直径计算需要一个更好的方法来实现。在本实验中,研究了完全偏心环空中的气液混合物的水平流动。用一个机械模型来评测摩阻压力损失,此模型引入的一个代表直径项既可以在环形管又能在环形空间几何形态中应用。流型的定义沿用了Taitel-Dukler提出的基本理论。对比结果发现,对于描述环形空间几何形态,引入的代表直径在实验中表现的比用水力直径更为准确。使用代表直径项,流型会测定得更加准确。最终结果表明,推荐模型可以准确地定义流型和测定摩阻压力损失,准确度低于20%。
Based on the advantages of underbalanced drilling technology, the number of wellbores that have been under-utilized by field-using underbalanced drilling has rapidly increased, with the advantages of increased penetration rate, lost circulation and differential calculus, minimized formation damage and many environmental advantages . In a coiled tubing underbalanced operation, a gas-liquid mixture is commonly used where hydraulic calculations of two-phase flow systems are essential. The geometrical flow pattern in the horizontal section of the wellbore is completely eccentric and annuli and requires a real mechanical model. Little research has been done on the two-phase flow in the ring geometry space. Usually, the ring geometry is represented by the hydraulic diameter, and the relationship of the ring tube using the hydraulic diameter instead of the annulus diameter. However, basic hydraulic diameter calculations need a better way to do this. In this experiment, the horizontal flow of a gas-liquid mixture in a completely eccentric annulus was studied. A mechanical model is used to evaluate the frictional pressure loss. A representative diameter term introduced by this model can be applied both in a toroidal tube and in an annular space geometry. The definition of flow pattern follows the basic theory proposed by Taitel-Dukler. The results of the comparisons revealed that for the description of annulus geometry, the representative diameter introduced was more accurate than the hydraulic diameter in experiments. Using the representative diameter term, the flow pattern will be measured more accurately. The final results show that the proposed model can accurately define the flow pattern and determine the frictional pressure loss with an accuracy of less than 20%.