石油学报 ›› 2010, Vol. 31 ›› Issue (2): 318-321.DOI: 10.7623/syxb201002025

• 石油工程 • 上一篇    下一篇

油套环空放空防止气井井筒生成水合物技术

李颖川 1,2 王志彬 2 钟海全 2   

  1. 1西南石油大学油气藏地质及开发工程国家重点实验室 四川成都 610500; 2西南石油大学石油工程学院 四川成都 610500
  • 收稿日期:2009-06-29 修回日期:2009-11-10 出版日期:2010-03-25 发布日期:2013-10-31
  • 通讯作者: 李颖川

Annulus pressure unloading technology against generation of natural gas hydrate in the wellbore of gas well

LI Yingchuan 1,2 WANG Zhibin 2 ZHONG Haiquan 2   

  • Received:2009-06-29 Revised:2009-11-10 Online:2010-03-25 Published:2013-10-31
  • Contact: LI Yingchuan

摘要:

基于气液两相流沿气井油管上升流动过程中质量和动量守恒及井筒传热机理,建立了压力和温度梯度耦合模型,并采用四阶龙格库塔法数值求解。该模型中考虑了流体的焦耳汤姆逊效应及环空介质和地层热物性沿井深的变化,分析了大牛地低渗低产D2-56气井环空介质换热系数和井筒总传热系数与套压的关系。计算结果表明:若井下安装封隔器,并将油套环空放空,可显著降低井筒总传热能力和油管内流体的热损失,提高油管内流体温度,可防止水合物在油管中生成。对于产量较高的气井,降低油套环空压力对防止水合物生成更具有实用性。

关键词: 气井, 井筒流动, 气液两相流动, 传热机理, 环空放空技术, 水合物生成

Abstract:

The flowing pressure and temperature gradient coupled model was derived on the basis of the mass and momentum conservation mechanism of gas-liquid upward flow in tubing and heat transfer mechanism of wellbore. The model was numerically solved with the fourth-order Runge-Kuta algorithm. The Joule-Thomson effect of fluid and the change of heat transfer medium in annular and the physical properties of the formation along the well depth were considered in the model. The relations of annulus convective heat transfer coefficient and the total heat transfer coefficient in wellbore with casing pressure were theoretically analyzed. The analysis of the low-permeability and low-production Daniudi D2-56 gas well showed that the total heat transfer capacity and heat loss of well-bore would obviously decline, if a packer was installed down-hole and the casing pressure was unloaded, which would enhance the fluid flowing temperature and thus prevent the generation of gas hydrate. Furthermore, reducing the annulus pressure of high-production gas well is more practical to prevent hydrate generation.

Key words: gas well, wellbore flow, gas-fluid two-phase flow, heat transfer mechanism, annulus pressure unloading technology, gas hydrate generation