With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic （TEM） method is f...With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic （TEM） method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goal is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goals are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to orosoect a multilaver water-filled goaf is feasible.展开更多
推导了斜阶跃场源激励下采样零时刻在发射电流关断处的均匀导电半空间瞬变响应解析式,分析了斜阶跃场源激励下的磁场、感应电压与视电阻率的对应关系,指出用感应电压定义的全程视电阻率可能存在无解或多解的情况。提出了一种全程视电阻...推导了斜阶跃场源激励下采样零时刻在发射电流关断处的均匀导电半空间瞬变响应解析式,分析了斜阶跃场源激励下的磁场、感应电压与视电阻率的对应关系,指出用感应电压定义的全程视电阻率可能存在无解或多解的情况。提出了一种全程视电阻率直接计算方法,将发射电流关断时间作为系统参数参与视电阻率的计算,可以方便地计算出中心回线装置下测量目标的全程视电阻率。理论模型的分析与Electromagnetic Model Analysis软件计算数据的比较证明了这种数值算法的可行性。不同于常规数据校正算法,提出的全程视电阻率直接算法具有更小的误差和更快的计算速度,由于斜阶跃场源技术的成熟,该算法具有一定的应用价值。展开更多
基金supported by the National Science Foundation of China(No.41374129)Science and Technology Project of Shanxi Province(No.20100321066)Research and Development Project of National Major Scientifi c Research Equipment(No.ZDYZ2012-1-05-04)
文摘With deep mining of coal mines, prospecting multilayer water-filled goaf has become a new content that results from geophysical exploration in coalfields. The central loop transient electromagnetic （TEM） method is favorable for prospecting conductive layers because of the coupling relationship between its field structure and formation. However, the shielding effect of conductive overburden would not only require a longer observation time when prospecting the same depth but also weaken the anomalous response of underlying layers. Through direct time domain numerical simulation and horizontal layered earth forward modeling, this paper estimates the length of observation time required to prospect the target, and the distinguishable criterion of multilayer water-filled goal is presented with observation error according to the effect of noise on observation data. The observed emf curves from Dazigou Coal Mine, Shanxi Province can distinguish multilayer water-filled goaf. In quantitative inversion interpretation of observed curves, using electric logging data as initial parameters restrains the equivalence caused by coal formation thin layers. The deduced three-layer and two-layer water-filled goals are confirmed by the drilling hole. The result suggests that when observation time is long enough and with the anomalous situation of underlying layers being greater than the observation error, the use of the central loop TEM method to orosoect a multilaver water-filled goaf is feasible.
文摘推导了斜阶跃场源激励下采样零时刻在发射电流关断处的均匀导电半空间瞬变响应解析式,分析了斜阶跃场源激励下的磁场、感应电压与视电阻率的对应关系,指出用感应电压定义的全程视电阻率可能存在无解或多解的情况。提出了一种全程视电阻率直接计算方法,将发射电流关断时间作为系统参数参与视电阻率的计算,可以方便地计算出中心回线装置下测量目标的全程视电阻率。理论模型的分析与Electromagnetic Model Analysis软件计算数据的比较证明了这种数值算法的可行性。不同于常规数据校正算法,提出的全程视电阻率直接算法具有更小的误差和更快的计算速度,由于斜阶跃场源技术的成熟,该算法具有一定的应用价值。
