超临界CO水平环空携砂试验研究

Sand-Carrying Experiments with Supercritical CO in a Horizontal Annulus

孙晓 王海柱 李英杰 郑永 陆群

SUN Xiao WANG Haizhu LI Yingjie ZHENG Yong LU Qun

陕西延长石油（集团）有限责任公司研究院，陕西西安 710075 油气资源与探测国家重点实验室（中国石油大学（北京）），北京 102249 中国石油集团海洋工程有限公司，北京 100176

Research Institute of Shaanxi Yanchang Petroleum(Group) Co., Ltd., Xi’an, Shaanxi, 710075, China College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing,102249, China CNPC Offshore Engineering Company Limited, Beijing, 100176, China

为明确超临界CO2在水平段环空的携砂性能，分析关键施工参数对其携砂性能的影响，根据相似原理设计了超临界CO2水平环空携砂试验装置，试验研究了超临界CO2注入质量流量、砂比、出口压力和流体温度对砂粒在水平环空中运移的影响。试验结果表明：超临界CO2能够以悬浮输送的方式在水平环空内有效携砂，增大其质量流量，会增强环空内流体的紊流强度，进而提高悬浮携砂效果；在较高砂比下，水平环空底部更容易出现砂床，使过流面积减小，从而使砂粒运移速度增大；在相同注入条件下，环空内砂粒运移速度随出口压力升高而降低，但降低幅度逐渐减小；在合理温度范围内提高流体温度，有利于减少环空内砂粒的堆积。研究结果可为超临界CO2钻井和超临界CO2压裂优化设计关键施工参数提供参考。

According to the similarity principle, a device for sand-carrying tests was developed to determine the sand-carrying performance of supercritical CO2 in the horizontal annulus and analyze the effects of key operating parameters on the sand-carrying performance. The device was employed to explore the influence of the injection mass flow, sand concentration, outlet pressure, and fluid temperature of supercritical CO2 on the sand migration in the horizontal annulus. The results showed that supercritical CO2 could effectively carry sand in the horizontal annulus by means of suspension transport, and the increase in its mass flow could enhance the turbulence intensity of the fluid in the annulus and improve the sand-carrying effect by suspension transport. In a high sand concentration, sand beds were likely to occur at the bottom of the annulus, which reduced the open area and raised the sand transport velocity. Under the same injection condition, the sand transport velocity in the annulus decreased with the increase of outlet pressure, but the amplitude of reduction is gradually lowering. In addition, a rise in fluid temperature was conducive to the accumulation reduction of sand in the annulus in an appropriate temperature range. The research results can provide a reference for optimizing the key construction parameter design in drilling and fracturing with supercritical CO2.

国家自然科学基金项目“超临界CO缝内携砂机理研究”（编号：51874318）、陕西省创新能力支撑计划“CO压裂井筒温压及地层波及规律研究”（编号：2019KJXX-023）、国家自然科学基金项目“油气井流体力学与工程”（编号：51922107）联合资助

https://doi.org/10.11911/syztjs.2021099