Simulation Of Radar Detection For Leakage Of Underground Oil Pipeline

The leakage of buried oil pipeline will cause soil pollution,deterioration of water resources,and even threaten people's property and physical safety.It is of great theoretical and application value to explore accurate and efficient oil pipeline leakage detection methods and means and strive to reduce the loss caused by oil leakage.Radar detection,as one of the accurate and efficient methods for locating buried oil pipeline leaks,has the advantages of flexible operation and low cost.However,due to the influence of the complex underground environment,the radar measured data will be difficult to interpret.If the actual radar detection method is used to solve the above problems,it will cost a lot of human,material and financial resources.Therefore,the radar detection numerical simulation method can be used to study the radar detection of buried oil pipeline leakage,understand and master the radar echo characteristics,and provide the corresponding theoretical basis for the interpretation of pipeline leakage radar measured profile data,which has guiding significance.In this paper,the numerical simulation of radar detection of buried oil pipeline leakage is deeply studied.The specific work contents are as follows:(1)A small hole leakage diffusion model of buried oil pipeline is established.By analyzing the diffusion process of oil leaking from small holes of buried oil pipeline,the diffusion law of oil leakage under soil conditions with different porosity and water saturation is discussed.According to its diffusion form and range,the small hole leakage diffusion model of eccentric circle centered on the pipeline is established.(2)The forward simulation of pipeline leakage radar detection is studied and realized.Firstly,the Finite-Difference Time-Domian(FDTD)algorithm of layered half space dispersive media is discussed from the aspects of accurate and efficient introduction of excitation source,dispersive media and the truncation of calculation region.Then,the dielectric model of oil-contaminated soil is established according to the seepage law and diffusion model of leaked oil,and this method is used to simulate the different diffusion conditions of the leaked oil.By analyzing the radar echo profile,it can be found that when the pipeline does not leak,the echo curve is relatively complete,and with the increase of porosity and water saturation,the relative dielectric constant of soil will keep increasing,and the curvature and two-way travel time of echo curve will also gradually increase;In case of pipeline leakage,there will be messy superimposed waves and shadowed parts on the radar echo profile,and the larger the polluted area is,the larger the area of clutter and shadow parts will be.Finally,according to the above characteristics,whether the pipeline leaks and the size of the polluted area can be determined.(3)The degree of oil pollution near the ground surface was studied.By establishing a model of layered oil contamination on the near-surface,the layer velocity in the radar echo data is obtained by using the common center point velocity inversion method,the corresponding dielectric constant is calculated,and the water content and oil content of the oiled soil are calculated according to the hybrid dielectric model,so as to judge the pollution degree of the soil.It has great research potential and value for determining the pollution of the oil contaminated soil near the ground surface leaked by oil pipelines.