Analysing the leak detection sensitivity for a particular system, or predicting how operational transients influence it, are common challenges for leak detection professionals.
An empirical approach can be followed: modeling the pipeline system, including all the inaccuracies due to the instruments and communication systems. The sensitivity can then be inferred by running specific scenarios.
Designing the scenarios is not a trivial task. The system response to transients provides information about sensitivity degradation. This information is used to plot a sensitivity map, which in turn helps to understand the more favorable and less favorable sensitivities for a particular system.
Colombian oil company, Ecopetrol, followed this practical procedure for a new pipeline in the commissioning phase. This allowed a pre-determined estimate of the system sensitivity and an evaluation on the operational transients involved in the leak detection tests.
The present paper describes the approach which Ecopetrol followed during model construction, the design of scenarios and the results obtained. API 1149 steady state and transient predictions are also compared with the model results. A sensitivity map considering both sources of data is analyzed. Finally, the paper presents a discussion about the validity of this procedure and its generic application.
Ecopetrol, the national oil and gas company in Colombia, carried out a leak detection sensitivity analysis for a pipeline prior to commissioning.
The procedure included the configuration of an off-line model, the design of leak test scenarios, the addition of uncertainties to the hydraulic variables and running a leak detection system.
The leak test results from the model are compared with the API 1149 steady state estimations and the sensitivity degradation due to uncertainties in system variables.