The analysis of pipeline leak tests using DEGADIS model

Pipeline leaks are of major concern to natural gas industry. They can result in loss of revenue, potential danger to public, and environmental damage. To ensure pipeline safety and reliability, a ground surveillance program to detect leaks is conducted on annual basis. Considering the number of miles of natural gas pipeline, this method is time consuming and expensive. There has been interest in developing other methods for rapid survey of natural gas pipelines. An aerial pipeline leak detection system has been developed recently that utilizes an aircraft equipped with flame ionization hydrocarbon detector for analyzing the samples taken over the pipeline right-of-way. The accuracy and reliability of the aerial surveys have not been verified.; A dispersion model, that predicts the trajectory and dilution of vertically oriented gas jet, was utilized to determine the optimum flight plan. The model was modified to develop user-friendly input and output interfaces. A pipeline leak was simulated by release of the natural gas during the field test. The measured gas concentrations by the aerial survey were compared to model predictions to evaluate reliability of the survey results and the predictability of the model. The measured gas concentrations were generally found to be in agreement with the predicted values. The results indicated that model can be used for design flight plan and analysis of the field data. The aerial leak detection system was found to be reliable in detecting gas anomalies at flight altitude of 100 feet.