Study On Product Oil Pipeline Pinhole Leakage Accidents Infiltration Influencing Factors

Along with the development of Chinese economy,Demand for product oil is increasing which is an important strategic energy source.At present,the main transportation method of product oil in China is pipeline transportation.Small hole leakage accidents will occur because of corrosion,wrong operation and tripartite damage of oil pipelines.The accident not only affects energy security and causes economic losses,but oil leakage will also infiltrate the surrounding soil and cause secondary environmental pollution.The leakage of the small hole leakage accident has a extremely small flow and hard to detect.Therefore,studying the infiltration law of the oil leaked from the small hole leakage accident in soil is significance for predicting the cumulative infiltration amount and wetting front of the leaked oil and the subsequent accident treatment.This paper experimentally study on two key laws of soil infiltration,the cumulative infiltration amount and the velocity of the wetting front of the leaked oil infiltrating the soil around the pipeline after the small hole leakage accident in the product oil pipeline.In this study,three representative soils(coarse sand,fine sand,and silt)were selected according to the international soil particle classification system,and the soil physical properties were measured in detail.92 # gasoline,0 # diesel and water were selected as infiltration fluids and the complete characteristic curves of different infiltration fluids in each experimental soil were measured.Characteristic curve function was calculated with software.Based on the analysis of the results,the soil with smaller particle size has greater matrix potential energy under the same experimental conditions and has stronger holding power for 92 # gasoline,0 # diesel and water.Which will cause greater obstacles to the movement of infiltrating fluids therein.Therefore,when lying the refined oil pipeline,a fine sand impervious layer is arranged on the side of the pipe wall to reduce the leakage effect.In order to simulate the infiltration in the layered soil after the leakage of small hole leakage accident.This study designed a soil layered infiltration experiment.Based on the analysis of the experimental results the wetting front migration speed of the experimental fluid infiltration was 92 # gasoline the fastest water is the second and 0 # diesel is the slowest.In soils with different particle sizes,the cumulative infiltration amount is mainly determined by the soil porosity,initial moisture content and saturated moisture content.In the same infiltration fluid infiltration experiment the cumulative infiltration amount is the largest for coarse sand and the second for fine sand.In order to accurately describe the cumulative infiltration volume of the infiltration fluid and the movement law of the wetting front this study modified the parameters and forms of the traditional Green-Ampt infiltration mathematical model and introduced the concept of impermeability to comprehensively describe the analysis.Layer soil interface hinders fluid infiltration.By comparing the traditional infiltration mathematical model with the Hydros-1D infiltration software,the modified infiltration mathematical model in this study can more accurately calculate the wet front of 92 # gasoline,0 # diesel and water infiltration in layered soil.The migration situation and accumulated infiltration can provide guidance and reference for the prediction of the cumulative infiltration of small leaks in small oil flow pipelines for a long period of time and the study of infiltration of wet fronts.