V8系统CSAMT法在福建山区找煤应用——以龙岩林邦矿区为例

Application of V8 System CSAMT Method in Coal Looking in Fujian Mountainous Area——A Case Study in Linbang Mine Area,Longyan

福建山区由于受地形、地质构造等诸多复杂因素影响,常规电法勘探中数据采集困难,处理解释精度较低,尤其是在老地层、火山岩和红层覆盖下的"三下"隐伏区找煤,更难取得令人信服的结果。为突破山区深部找煤难题,在龙岩林邦矿区,使用V8系统进行了CSAMT法勘探。在分析已有地质资料与物性特征的基础上,采用旁侧排列进行施工,发送频率选择为0.125～7 680Hz的48个频点,发送电流为8A,采用水平电偶极子,电极源长度AB为2km。在资料处理中重点采用了人工消除畸变点、去近场效应和静态较正等技术手段,有效克服了地形、地质构造等复杂因素的影响。并以K7线的实测地电断面图为例,指出了异常与本区沉积层序规律的矛盾,最终经静态校正的Bostick模型2D反演,原断面图上跳越畸变和断裂状失真完全消失,异常分布形态连续完整,层带状反映清晰有序。钻孔验证结果表明,其解释成果与钻探结果基本吻合。

Since the impacts from many complex factors such as topography,geologic structures in the Fujian mountainous area,data acquisition is difficult;processing and interpretation degrees of accuracy are low when using conventional electric prospecting.Especially in ＂3 under＂（under old strata,volcanic rocks and red beds） concealed areas are more difficult to get convincing results.To surmount coal looking hard nut in mountainous area deep part,V8 system is used to carry out CSAMT method prospecting in the Linbang mine area,Longyan.Based on available geologic data and physical property characteristic results,side arrangement is used in operation,emission frequency 0.125~7680Hz of 48 freqs,sending current 8A,horizontal electric dipole,electrode spacing AB 2km.Technical means of artificial distortion point and near-field effect eliminations and static correction are used emphatically in data processing,thus overcome impacts from complex factors of topography,geologic structures effectively.Taking the K7 line measured geoelectric cross section as an example,pointed out contradiction between anomaly and sedimentary sequence pattern in the area.After static corrected Bostick model 2D inversion,skipping and fracture-like distortions on original sections have fully disappeared finally,anomaly distribution pattern continuous and intact,bedded and banded reflections clear and ordered,After drilling verification has demonstrated that the results of interpretation and drilling are fitted closely.