气井井筒水合物预测研究

Prediction of borehole hydrate in gas well

天然气中的各种组分分子在一定温度和压力下,与游离水结合,形成结晶笼状固体,在生产的过程中会堵塞油管,严重的时候甚至造成停产。考虑井筒中天然气温度和压力的耦合,从井底逐点迭代计算出井筒中天然气温度、压力的分布,再用判别水合物的热力学模型逐点判别是否形成水合物和找出水合物生成的具体位置,为防止水合物的生成提供指导作用。可以通过降低井筒压力和提高井筒温度或降低天然气体系的形成温度2个方面着手预防水合物的生成,防止水合物生成可作为开发前期选择油管考虑的一个因素。

The components of natural gas are the methane, ethane, propane, isobutane, n-butane and a small number of N2, CO2, H2S. These components combine with the free water, which forms the cage-like crystalline solids at a certain temperature and pressure. In the process of production, the solids will plug the tube and even cut off producing. Considering the coupling of temperature and pressure, this paper calculates the distribution of temperature and pressure in tube from the bottom by way of the point-to-point iteration, and then identifies whether the hydrate was generated with the point-to-point discrimination by using the thermodynamic model and determines the specific location of hydrate generation. It provides a guide for the prevention of hydrate. We can reduce the pressure and increase the temperature or reduce the forming temperature of natural gas system in order to prevent the hydrate generation. The hydrate generation can he regarded as a consideration factor of oil tube selection in earlier development days.