超临界二氧化碳钻井时瞬态波动压力

Transient surge and swab pressure analysis of supercritical carbon dioxide drilling

丁璐 倪红坚 2

中国石油大学（华东）石油工程学院，山东 青岛 266580 中国石油大学（华东）非常规油气开发教育部重点实验室，山东 青岛 266580

School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China MOE Key Laboratory of Unconventional Oil & Gas Development, China University of Petroleum, Qingdao 266580, China

利用超临界二氧化碳开发油气藏资源极具潜力，但是有许多基础问题仍有待研究，瞬态井底波动压力变化问题是其中之一。基于超临界二氧化碳的物性，文中考虑了超临界二氧化碳与钻柱、井壁的传热，建立了井筒流动控制方程、瞬态控制方程，最终获得井底的热流固耦合瞬态波动压力模型。在停泵条件下，起下钻速度越快，井底波动压力越大。当地面入口温度增大时，最大波动压力降低；当地面出口压力增大时，最大波动压力增大；当起下钻速度为0.1~2.0 m/s时，最大激动压力从0.13 MPa升到3.86 MPa，产生的最大抽汲压力从0.13 MPa升到1.83 MPa。与清水钻井对比发现，超临界二氧化碳钻井产生的波动压力偏低，有利于现场作业，可以适当加快起下钻速度，提高工作效率。

Developing oil and gas reservoirs by supercritical carbon dioxide drilling has great potential, but many basic theoretical problems remain to be researched, such as the transient bottom hole pressure under the supercritical carbon dioxide drilling condition. Based on the physical property of the supercritical carbon dioxide, the heat transfer between supercritical carbon dioxide, drill string and wellbore has been considered. Then combining wellbore flow control equation and transient control equation, the heat-fluid-solid coupling transient surge and swab pressure model in bottom hole has been established. Under the condition of pump stopping, the larger the tripping speed is, the greater the pressure fluctuation range is. The maximum fluctuation pressure decreases with the inlet temperature increase, or increases with the outlet pressure increase. As the tripping speed is 0.1￣2.0 m/s, the maximum surge pressure increases from 0.13 MPa to 3.86 MPa, and the maximum swab pressure increases from 0.13 MPa to 1.83 MPa. Compared with water drilling, it is found that surge and swab pressure of supercritical carbon dioxide drilling is lower than that of water drilling, which is conducive to the field operation, and it can appropriately accelerate the tripping speed and improve the work efficiency.

10.6056/dkyqt202001024