Experimental Research On Three-Dimension Magnetic Imaging Of Sealing Slurry Flow Trace In Gas Extraction Borehole

With the increasing depth of coal mining,in-situ stress and the decreasing permeability of coal seams,gas accidents have been occurring more frequently.This poses a serious threat to mining safety.The key thing to consider is gas extraction,one of the important parts of which is borehole-sealing,which can determine the concentration of gas extraction.This paper discusses the issue of slurry flow trace of borehole-sealing slurry in magnetic imaging.It contains a mathematical model of magnetic unit strength for fractured rock-like materials as well as multi-magnetic field analyze software and an experiment into magnetic slurry ratios.Fractured rock-like material sealing was carried out by means of a three-dimensional(3D)scanning system aiming to reveal the magnetic propagation of fracture characteristics and slurry cemented in rock-like materials.This paper further provides a reference for the magnetic imaging technology of slurry.The main contents of paper are as following:(1)Based upon the principles of linear equations and the Back-Projection Algorithm,four groups of linear equations were built-namely the X-axis,Y-axis,Z-axis and diagonal axis so as to develop multi-magnetic field analyze software.This model solution was developed in order to calculate the magnetic strength o.f each point within a prior defined acceptable accuracy range.(2)The multi-level and multi-factor experiment of ratio sealing slurry was conducted and coupled with slurry flow characteristics and sedimentation rates to determine the optimum sealing slurry ra,tio of fractured rock-like materials.(3)Three sides of cemented rock-like materials were analyzed using a 3D scanning system to study the magnetic propagation in fracture characteristics of rock-like materials.(4)Based on experimental results,the magnetic strength of typical cross-sections of material was analyzed by Matlab software to obtain the fractured characteristics reflected by various magnetic strengths.Thus,the solution model was employed to calculate magnetic strength in each point alongside the three-dimensional magnetic strength propagation in a typical cross-section.The results of this study reveal that the feasibility of sealing slurry flow with trace magnetic imaging by using magnetic particles as markers and then the model solution of magnetic units for rock-like materials was developed within acceptable accuracy ranges.This paper therefore claims to provide the necessary references and instructions required to successfully utilize seal slurry imaging.