Research Topic: Oil and gas transmission pipelines are considered critical energy-transportation arteries of the country and are exposed to various threats. Natural phenomena such as earthquakes and floods, as well as human-related factors including unsafe excavation activities and operational failures, are among the main causes of leakage and disruption in the performance of transmission lines. The 16-inch Mansouri field pipeline, with a length of 33 km, is used to transport 75,000 barrels of crude oil per day from the field’s gathering center to the Ahvaz booster pump station. In this study, the pressure drop along the pipeline and the volume of fluid released into the environment due to leakage with different sizes have been calculated through transient flow simulation.
Methodology: The transient multiphase flow simulation is performed using the OLGA simulator. To construct the initial model, operational and field data were utilized. The initial hydraulic of the pipeline model was tuned with parameters such as internal pipe roughness, fluid viscosity, and gas-oil ratio (GOR) so that the final tuned model shows minimal deviation from actual operating conditions. This tuned model was then applied to predict the pressure drop and leakage flow rate. The modeling results obtained in this research can be used for designing leak-detection and leak-warning systems, particularly transient-model-based real-time systems.
Main Results: According to the results of this study, in the event of a leak with diameters of 1 cm, 10 cm, and a full-bore rupture, the rate of pressure drop at the pipeline inlet will be approximately 0.0001 bar/sec, 0.06–0.28 bar/sec, and 0.25–5 bar/sec, respectively. These values play a critical role in determining the automatic shutdown time in Real-Time Transient Models (RTTM).