利用井下节流技术防止水合物形成

Preventing hydrate generation with downhole throttling technique in gas well

井下节流技术是将节流嘴置于油管某一适当位置,使井筒压力降低,改变水合物形成条件,防止井筒水合物堵塞,同时可有效降低井口装置的压力,使井口装置更加安全可靠,使用寿命延长。为准确预测井下节流后气井井筒温度、压力分布,判断水合物形成条件,将井筒节流温压分布模型与水合物预测模型相结合,建立了气井井下节流水合物预测模型。结合油田实例,预测了气井节流后温度、压力沿井筒的分布,计算了节流后温度、压力条件下井筒内水合物的形成温度,为气井井筒水合物的防治提供了重要依据。在气井中,利用井下节流技术能够有效地防止水合物的形成,研究成果已用于指导双家坝气田采气工程设计。

Downhole throttling technique is to install the choke at a suitable depth of oil tube in order to reduce the borehole pressure, which changes the conditions of hydrate forming to prevent the hydrate plugging the oil tube. At the same time, the pressure of flow head can be effectively decreased to make the well head safe and reliable and to prolong the service life. To predict the distribution of borehole pressure and temperature accurately after downhole throttling in gas well and determine the hydrate forming conditions, the forecasting model of hydrate is set up by combining the distribution model of temperature and pressure of borehole throttling with the forecasting model of hydrate. Combined with field case, the distribution of temperature and pressure along the borehole after the gas well throttling is predicted and the forming temperature of hydrate in the borehole is calculated under the conditions of temperature and pressure after throttling, which provides an important reference for hydrate prevention of borehole in gas well. In gas well, using downhole throttling technique can prevent the hydrate forming effectively. The study result has been applied to guide the gas production engineering design in Shuangjiaba Gas Field.