钻进过程的Ra-Rn平衡位移效应

报道了钻孔揭穿砂岩铀矿体过程导致矿层Ra-Rn平衡位移的研究方法和研究结果.认为由于泥浆循环液等产生的压力大于含矿砂体层间静水压力,钻进过程会使井壁周边矿体中氡气向外围迁移,导致人为的Ra-Rn平衡位移,致使伽马测井照射量率下降;含矿砂岩本身的孔隙度和透水性等因素影响平衡位移幅度.发现Ra-Rn平衡恢复过程并非平稳连续,而呈台阶式跳跃上升.文章还对砂岩铀矿床Ra-Rn平衡系数的确定方法进行了讨论,认为目前工作中采用矿心Ra分析结果与伽马测井Ra解释结果对比计算Ra-Rn平衡系数的方法,不够科学,也不尽合理.

A study of Ra-Rn equilibrium displacement effects in drillings

This paper introduces the method and its results in determining the Ra-Rn equilibrium displacement during the drilling of sandstone uranium ore-bodies. The pressure produced by drilling fluid is often higher than the hydrostatic pressure in ore bodies during the drilling, and would forces the radon gas in ore bodies near boreholes to move toward outside, and as a consequence, a man made Ra-Rn equilibrium displacement will be produced, and finally a lowered -/-radiation dose rate in gamma logging is resulted in. The porosity and permeability of sandstone ore bodies are also factors affecting Ra Rn equilibrium displacement. Case studies using this new method find that the Ra-Rn equilibrium restoration is unstable and discontinuous, but increases with a leap. Determination methods of Ra-Rn equilibrium coefficient for sandstone-type uranium ore deposits are also discussed.