摘要
针对陕北侏罗系煤田风化基岩层富水性探查的实际需求,研究了地面瞬变电磁法晚期电阻率和一维反演成像对风化基岩富水性的反映特征。利用矿区测井电阻率曲线,分别建立了正常地层和风化基岩模型,并对模拟响应进行了晚期电阻率成像和一维反演成像。研究发现当存在风化基岩富水区时,晚期电阻率的中间高阻层在横向上整体表现为“高-低-高”的电性变化特征,在正常地层与风化基岩交界区域,中间高阻层视电阻率值最低、厚度最小,在风化基岩区域,浅部低阻层视电阻率幅值减小,中间高阻层视电阻率值降低,厚度也变小,而反演电阻率中间高阻层电阻率基本稳定,厚度与正常地层的基本一致;在正常地层与风化基岩交界区域,中间高阻层反演电阻率幅值升高,厚度增大;在风化基岩区域,浅部低阻层电阻率幅值减小,风化基岩电性特征更为明显。通过比较一维反演与晚期视电阻率断面,一维反演电阻率成像结果更能客观反映地层的实际情况,不会带来虚假异常现象。通过现场工程试验证明了上述理论的正确性。
In view of the actual demand for exploring the water rich property of weathered bedrock in the Jurassic coalfield in northern Shaanxi,the reflection characteristics of the late resistivity of ground transient electromagnetic method and one-dimensional inversion imaging on the water-rich property of weathered bedrock were studied.First,the normal stratum and weathered bedrock models were established by using the logging resistivity curve of the mining area,and the late resistivity imaging and one-dimensional inversion imaging were carried out for the simulation response.It was found that when there was a weathered bedrock water-rich area,the middle high-resistivity layer of late resistivity generally showed an electrical property change characteristics of horizontal"high-low-high";in the boundary area between normal stratum and weathered bedrock,the middle high-resistivity layer had the lowest apparent resistivity value and the smallest thickness;in the weathered bedrock area,the apparent resistivity amplitude of the shallow low-resistivity layer decreased,the apparent resistivity value of the middle high-resistivity layer decreased,and the thickness also decreased.While the resistivity of the middle high-resistivity layer in the inversion resistivity was basically stable,and the thickness was basically consistent with the normal stratum;in the boundary area between normal stratum and weathered bedrock,the inversion resistivity amplitude and thickness of middle high-resistivity layer increased;in the weathered bedrock area,the resistivity amplitude of the shallow low-resistivity layer decreased,and the electrical property characteristics of the weathered bedrock were more obvious.In addition,by comparing one-dimensional inversion and late apparent resistivity section,the results of one-dimensional inversion resistivity imaging could objectively reflect the actual situation of the stratum and would not bring false anomalies.Finally,the correctness of the theory was proved by engineering testing.
作者
马留柱
MA Liuzhu(CCTEG Xi'an Research Institute,Xi'an,Shaanxi 710077,China)
出处
《中国煤炭》
2023年第5期50-57,共8页
China Coal
基金
陕西省自然科学基础研究计划重点项目(2022JZ-16)。
关键词
瞬变电磁法
侏罗系煤田
风化基岩层
晚期电阻率成像
一维反演成像
富水性
transient electromagnetic method
Jurassic coalfield
weathered bedrock layer
late resistivity imaging
one-dimensional inversion resistivity imaging
water-rich property
