Forward Modeling Of Resistivity Detection Of Channel Leakage In High Salinization Area

There is serious leakage along the brine transport canal of Lop Nur potash mine.In the290 Km long brine transport canal,the loss of leakage is as high as 40%,which has greatly affected the economic benefit of Luo potassium salt field.Therefore,it is urgent to carry out leakage exploration on the brine transport canal without affecting the normal production.Lop Nur potash mine is located in the northern part of Lop Nur Lake.The area is multi-layered lacustrine deposition,and the shallow surface is interbedded structure of multi-layered salt crust and fine sand.The artificially excavated channels are long and narrow,and the temperature difference between day and night in this area is great.In view of the salinization of the surface of the observation area,the narrow and long research object and the bad natural conditions,the resolution of the conventional electric(magnetic)exploration device is limited and the field observation conditions are not ideal,so it is necessary to explore a new observation scheme.In this study,the field geological survey was firstly carried out,and the small quadrupole experiment was carried out for water body,canal bottom and canal levee to obtain the electrical parameters of exploration object and research area,and the model parameters in the calculation process were set on the basis of the data.Second use resistivity method symmetric quadrupole profile devices feasibility physical flume experimental research,using PVC sheet to simulate the luo potassium lose halide high resistance soil anti-seepage membrane canal lining,and open hole on the PVC board anomaly area,the experimental results show that by resistivity method to find the luo potassium channel leakage point is feasible,but on the observation instrument accuracy and high resolution requirements.Then,according to rokk field data,the model was modeled using Comsol Multiphysics software.Based on the field physical parameters,the values of the corresponding regions of the model were set.Then,the model was divided into grids,the first level of the study area was divided into multiple regular hexahedra,and the hexahedron was divided into six tetrahedra.The grid size is set to an appropriate size while ensuring the calculation accuracy and speed.Finally,according to the analysis of the geological situation on site,the channel may leak due to the large temperature difference between day and night,the erosivity of brine,fracture activity and other factors,so the tubular,spherical,linear and conical underground anomalies are set up to simulate the different conditions that may occur on site.After calculation,the results show that the volume of abnormal body is 0.5m3,and the relative abnormal size of 1% is obtained.Power supply electrode distance AB=30m,change the measurement pole distance for calculation,when the measurement pole distance MN=8m,the calculated relative anomaly size is 0.15%;When the model remains unchanged,the abnormal body is a cone with R base =1.5m,H=0.5m,AB=30m,MN=2m.The lateral offset distance of the survey line relative to the abnormal body is changed.When the offset distance exceeds 4m,the relative anomaly size is less than 0.1%.According to the above calculation results,firstly,resistivity method can be used to explore channel leakage in high salinization areas,and the waste of resources caused by channel leakage can be greatly reduced by using this method.Secondly,the simulation results can provide a theoretical basis for the exploration of high salinization channel seepage and become the basis for the use of resistivity method in the exploration of high salinization channel seepage in the future.Finally,the best survey line arrangement can be selected to accelerate the exploration efficiency.