Exploration characteristics of coal and rock boundary in horizontal well with Azimuth electromagnetic wave instrument PeriScope

In coal mine production, advance and precise identification of coal-rock interface can improve recovery and reduce mining risk, which is one of the bottleneck technologies to realize intelligent coal mining. Azimuth electromagnetic wave logging instrument has larger detecting depth and the azimuth resolution ability, which has a certain advantage in coal-rock interface detection, in order to study the oil the applicability of the azimuth electromagnetic wave instrument Periscope in coalfield well logging, coal log level layered formation model was established, using the generalized reflection coefficient method and finite element numerical simulation method, Taking Periscope as an example, the detection characteristics of coal seam boundary are investigated. Application of Periscope instrument transmitting frequency and spacing, set its instrument radius drill pipe radius of the commonly used for coal mine, the simulation results show that the geological response in line with the typical characteristics of signals in the interface, geological signal change with instrument rotation Angle with periodic response, frequency and delineation of distance is not a simple positive correlation, spaced and offset distance have positive correlation, The geological signal amplitude increases with the increase of coal layer thickness, but when the thickness increases to a certain value, the geological signal does not change with the thickness. When the eccentricity is large, the geological signal is affected by the eccentricity, and the azimuth electromagnetic wave measurement response can reflect the resistivity change of the goaf. Results show that the geological signal detection ability of the coal rock boundary by frequency resistivity contrast, layer thickness, spacing, and a variety of factors, such as electromagnetic wave instrument Periscope bearing geological signal has the azimuth resolution, can be used to set of coal rock interface detection model and identification of mined-out area, but in the case of surrounding rock and coal seam resistivity are high, It is necessary to increase the source distance of the instrument or select the appropriate transmission frequency to meet the requirements of the measurement signal intensity.