Physical Basis of Software-Based Leak Detection Methods

There are many causes for a pipeline to leak. Third party punctures usually result in sizable leaks. The onset of such leaks generates a sudden change in the pipeline pressure and flow. Methods exist that rely upon these sudden changes for leak detection. Leaks previously undetected are not detectable by such methods. These pre-existing leaks are usually small in size but can exist for long time. The cumulation of leaked products may pose a greater hazard then the larger and sudden leaks. The operational experience of major pipeline company in the United States has demonstrated that all leak detection methods have their limitations, and that complementary leak detection methods should be used simultaneously (Mears 1993). Hence, we propose a leak detection system that uses, simultaneously, two independent but complementary methodologies: mass balance and transient flow simulations.