超临界CO2钻井井筒水合物形成区域预测

The Prediction of Hydrate Formation Regions in the Wellbore during Supercritical Carbon Dioxide Drilling

孙小辉 孙宝江 王志远 王金堂

Sun Xiaohui Sun Baojiang Wang Zhiyuan Wang Jintang

中国石油大学(华东)石油工程学院, 山东青岛 266580

School of Petroleum Engineering, China University of petroleum(Huadong), Qingdao, Shandong, 266580, China

为了保证超临界CO2钻井安全并快速钻进,需要解决井筒内水合物生成的问题。为此,在分析水合物形成机理的基础上,建立了超临界CO2钻井井筒水合物形成区域预测模型,并给出了模型的定解条件和数值求解方法。通过设计算例进行了计算分析,结果表明:环空内水合物形成区域的临界井深,随注入温度或水合物抑制剂加量增大呈二次多项式非线性下降;随井口回压增大先呈对数函数增大、后呈二次多项式关系增大,增大的幅度逐渐变小。分析结果可为超临界CO2钻井防治水合物形成提供理论参考。

In order to improve the safety and efficiency of SC-CO2 drilling (supercritical carbon dioxide drilling), it is necessary to deal with the formation of CO2 hydrate in the wellbores. Based on the hydrate formation mechanism analysis, a model for predicting the formation region of CO2 hydrate in the wellbore was built up, and the definite conditions and numerical resolution methods were proposed. Computational analysis was carried out by designing examples. It was shown that hydrate formation in the annulus decreased non-linearly in quadratic polynomial relations with the increasing of injection temperature or inhibitor dosage. And with the increasing of wellhead back pressure, hydrate formation increased with increasing rate reducing gradually (first in logarithmic relations and then in quadratic polynomial relations). The research achievements could provide a theoretical reference for hydrate prevention during SC-CO2 drilling.

国家自然科学"页岩气储层超临界二氧化碳压裂裂缝中支撑剂输送机理研究"(编号:51104172)、国家自然科学"非常规天然气储层超临界二氧化碳压裂工程基础研究"(编号:U1262202)和中央高校基本科研业务费专项资金(编号:15CX06020A)联合资助。

https://doi.org/10.11911/syztjs.201506003