两相态多物质高温射流钻井井下流场模拟分析  

Numerical Analysis of Two-Phase Multi-Material Flow Field in Hydrothermal Jet Drilling

作　　者：崔柳 纪国栋 韦海涛 姬佳炎 吕泽昊 Cui Liu;Ji Guodong;Wei Haitao;Ji Jiayan;Lü Zehao(CNPC Engineering Technology R&D Company Limited;Sinopec International Petroleum Exploration and Production Corporation;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing))

机构地区：[1]中国石油集团工程技术研究院有限公司 [2]中国石化集团国际石油勘探开发有限公司 [3]中国石油大学(北京)油气资源与探测国家重点实验室

出　　处：《石油机械》2019年第8期55-60,共6页China Petroleum Machinery

基　　金：中石油钻井新技术新方法“高围压下热力射流破岩效率实验研究”(2016A-3902);中石油创新基金项目“热力射流冲击——裂解耦合破岩机理研究”(2015D-5006-0308)

摘　　要：高温射流是一种适用于深部硬地层的新型钻井方法,它通过井下反应器中超临界氧化反应生成高温高压的射流破岩,因此对不同相态、多物质条件下高温射流钻井井底流场进行瞬态分析,并考虑不同地层的岩屑直径大小对井底流场的影响,模拟条件更加符合实际钻井井底状况。研究结果表明:冷却水紧贴钻井管柱上返,可以有效地对管柱进行降温保护,防止管柱高温失效破裂;超临界水与冷却水之间存在一个较薄的温度变化过渡层,最大比热容均处在超临界流体边界,可以较好地捕捉超临界水和亚临界水的分布;Peng-Robinson状态方程可以较准确地对二氧化碳的热物理性质进行模拟;在实际钻井过程中,可以通过控制高温射流与冷却水的注入比例调节环空温度,防止出现高温井壁坍塌等事故;岩屑直径越大,高温射流作用的区域越大,更加易于清理。研究结果可为高温射流钻井提供理论依据。Hydrothermal jet drilling is a new type of drilling method suitable for deep hard formation. It generates high-temperature and high-pressure jet to break rock through supercritical oxidation reaction in downhole reactor. The transient analyses on bottomhole flow field of hydrothermal jet drilling is conducted under different phases and multi-materials. The influence of the size of the cuttings in different formations on the flow field of bottomhole is also considered. Therefore,the simulation conditions are more in line with the actual bottomhole conditions.The study results show that the cooling water flows up close to the drill string,which can effectively cool the drill string and prevent the high temperature failure. There is a thin temperature transition layer between the supercritical water and the cooling water. Its specific heat capacity is at the supercritical fluid boundary,making it preferable to capture the distribution of supercritical water and subcritical water. The Peng-Robinson equation of state can accurately simulate the thermophysical properties of carbon dioxide. In the actual drilling process,the annular temperature could be adjusted by controlling the injection ratio of the hydrothermal jet and the cooling water to prevent downhole accidents like wellbore collapse of high-temperature well. Larger cutting diameter results in a larger hydrothermal jet area,where cutting removing is better. The study results can provide a theoretical basis for hydrothermal jet drilling.

关 键 词：高温射流 冷却水 两相态 超临界流体 岩屑直径 井底流场 

分 类 号：TE248[石油与天然气工程—油气井工程]