非均匀地应力条件下新疆某铀矿地浸井套管稳定性研究  

Study on Casing Stability Under Non-uniform Ground Stress for In-situ Leaching Well of a Uranium Deposit in Xinjiang

作　　者：李坡[1] 杨立志[1] 赵利信 周根茂[1] 李召坤 LI Po;YANG Lizhi;ZHAO Lixin;ZHOU Genmao;LI Zhaokun(Beijing Research Institute of Chemical Engineering and Metallurgy,CNNC,Beijing 101149,China)

机构地区：[1]核工业北京化工冶金研究院,北京101149

出　　处：《铀矿冶》2022年第4期368-376,共9页Uranium Mining and Metallurgy

基　　金：国家自然科学基金资助项目(U1967208)。

摘　　要：地应力变化导致套管损坏是地浸采铀过程中遇到的难题。依托钻孔电视的扫描图像和饼状岩芯,并结合附近区域的实测地应力数据,对新疆某铀矿区的地应力特征进行了估算。结果显示,矿区内最大水平主应力的方向为NNE16°,量值约为25.54 MPa。在测试深度范围内,三向主应力之间的大小关系为S_(H)>S_(V)>S_(h),S_(H)/S_(V)为1.6~1.1,S_(h)/S_(V)为1.1~0.8,该地区在地壳浅部水平应力占主导地位。以UPVC套管-水泥环-地层组合结构为研究对象,建立有限元模型进行数值模拟,结果表明非均匀地应力是UPVC套管损坏的重要原因;泥岩蠕变会加剧地应力的不均匀度,加快UPVC套管的损坏。在非均匀地应力状态下,套管在720 m深度运行8年时塑性应变达14%,接近破坏塑性应变(15%),套管很可能发生破坏或过度变形。Casing damage caused by in-situ stress changes is a difficult problem encountered in the process of in-situ leaching uranium.Based on the pie core and scan images of borehole TV,combined with the measured in-situ stress nearby,the in-situ stress characteristics of a uranium mine in Xinjiang were estimated.The results show that the direction of the maximum horizontal principal stress in the mine is NNE16°,the magnitude of it is about 25.54 MPa.Within the scope of tested depth,the relationship among the magnitude of the principal stress is S_(H)>S_(V)>S_(h),S_(H)/S_(V) is 1.6~1.1,S_(h)/S_(V) is 1.1~0.8,which indicate that the horizontal stress dominate control the stress field in this area.Taking UPVC casing-cement sheath-stratum combined system as study target,the finite models were established.The numerical simulation results show that the non-uniform ground stress is the important cause of main casing damage.Meanwhile the mudstone creep will aggravate the non-uniformity of the ground stress.The larger the stress differential is,the easier the casing will be plastic damage.Under the condition of non-uniform stress,the plastic strain reaches 14%at a depth of 720 m for 8 years and close to the plastic strain of 15%.The casing is likely to be damaged or excessively deformed.

关 键 词：地应力 套管损坏 蠕变 套管稳定性 有限元分析 

分 类 号：TD868[矿业工程—金属矿开采]