温压耦合影响下科学钻探深井结晶岩层井壁稳定性分析  

Wellbore Stability of Crystalline Rock Formation in the Scientific Deep Well under the Coupling Effect of Temperature and Pressure

作　　者：雷家蔚 王李昌 隆威[1,3] 黄大桂[1] LEI Jiawei;WANG Lichang;LONG Wei;HUANG Dagui(School of Geosciences and Info-Physics,Central South University,Changsha,Hunan 410083;China Railway ERYUAN Engineering Group.CO.LTD,Chengdu,Sichuan 610031;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,Changsha,Hunan 410083)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083 [2]中铁二院工程集团有限责任公司,四川成都610031 [3]有色金属成矿预测与地质环境监测教育部重点实验室(中南大学),湖南长沙410083

出　　处：《地质与勘探》2020年第5期1080-1086,共7页Geology and Exploration

基　　金：湖南省自然科学基金(编号:2020JJ5707);有色金属成矿预测与地质环境监测教育部重点实验室(编号:2019YSJS16);自然资源部深部地质钻探技术重点实验室(编号:KF201901)联合资助。

摘　　要：科学钻探深井结晶岩处在高地应力、高地层压力和高地温的"三高"环境中,其自身结构特征和物化特性会发生根本性变化,因温度变化引起的应力变化极易导致井壁失稳。本文依据温压耦合影响下坍塌压力和破裂压力计算模式,确定不同井壁温度下的安全钻井液密度窗口,通过FLAC3D开展温压耦合影响下井壁稳定数值模拟,分析在不同钻井液密度下井眼打开后不同时间的井壁周边温度和井壁稳定变化情况。结果表明:地层弹性参数对地层破裂压力的影响较大,对于花岗岩此类弹性模量较大的结晶岩,温度变化对破裂压力影响更大;井壁处附加应力受温度变化的影响程度:附加周向应力>附加径向应力>附加垂向应力;在最小主应力方向的井壁周边地层等效应力与钻井液密度呈正比关系,在最大主应力方向呈反比关系。The crystalline rock in a scientific deep well is situated in a environment of high geostress,high formation pressure and high geo-temperature.Its structural characteristics and physical and chemical properties can change fundamentally.Stress change caused by temperature variation can easily lead to wellbore failure.Based on the calculation model of collapse pressure and fracture pressure under the coupling effect of temperature and pressure,this paper determines the safe drilling fluid density window under different borehole temperatures.The numerical simulation of wellbore stability under the coupling effect of temperature and pressure is carried out by FLAC3D,and the change of wellbore surrounding temperature and wellbore stability at different time after the wellbore is opened under different drilling fluid density are analyzed.The results show that the formation elastic parameters have a great influence on the formation fracture pressure,and the temperature change has a greater influence on the fracture pressure for the crystalline rock with large elastic modulus,such as granite.The influence degree of the additional stress at the wellbore is affected by the temperature change:the additional circumferential stress>the additional radial stress>the additional vertical stress.The Von Mises equivalent stress around the wellbore in the direction of the minimum principal stress is proportional to the drilling fluid density and inversely proportional to the drilling fluid density in the direction of the maximum principal stress.

关 键 词：结晶岩 温压耦合 井壁稳定 数值模拟 深井 科学钻探 

分 类 号：P634.1[天文地球—地质矿产勘探]