Automated Pipeline Leak Detection at UNBC
About three years ago, Fluxo supplied 60 flow meters from Controlotron, currently Siemens, to the UN-BC pipelines. The flow meters, together with software developed by Petrobras itself, make up the Automated Leak Detection System (SDVZ), which is currently fully operational at Petrobras. Those responsible for implementing the system Alcio Chiesse and Paulo Coelho wrote an article specifically for the Fluxo newsletter:
To meet the precepts of its operational excellence program, Petrobras installed an automated leak detection system – SDVZ in the UN-BC pipelines. The current installation uses communication drivers and detection software – SDVO developed in-house. The premise of the project was the detection of leaks, where it was possible to measure the flow at both ends. The SDVO program currently monitors more than ten UN-BC pipelines. The start of the operation took place in March 2005.
The SDVO Software is a deterministic, transient and real-time state estimator, which solves the balances of the fundamental quantities of the flow (mass and momentum), without inserting the energy equation, that is, not formally solving the transfer problem. of heat. It offers an effectively transient RTTM model, written by KOSSATZ (1997), suitable for approximately isothermal flows. Subsequently, the program considered viscosity as a function of temperature, which is composed from the values observed at the ends of the pipeline, interconnecting along the way through an adjustable exponential curve.
Its quantification algorithm employs the head-to-tail flow rates, corrected for the atmospheric pressure condition, integrating their difference over time. Controlotron DVX1010 clamp-on ultrasonic transmitters are used for flow measurement.
The program was developed internally at the Petrobras Research Center – Cenpes, aiming to be used in single-phase pipelines with a full column, with transitions in diameter and steel thickness, and can accompany batches.
Independent of the leak detection software, a function was made available to calculate the ratio between the inlet and outlet volumes in the system, covering a time window of 5 minutes. These volumes are the sum of the last 5 volumes of 1 minute, using the value totaled by the flow transmitter, in order to eliminate integration errors. All ducts in operation at UN-BC, where measurement is possible at both ends, have this monitoring.
The leak detection system – SDVZ, although autonomous, forwards alarms and operational information to the supervisory systems of the production units, so that the operation has a single supervisory interface. The system HMI hosts the leak detection software and communication drivers. Such a station is considered “master” and its access is restricted to maintenance and support personnel. The SDVZ is made up of a few master stations.
Alcio Rodrigues Chiesse is an equipment engineer at Petrobras / UNBC / ST / AUT and Paulo Salgado Machado Coelho is a systems analyst at Petrobras / Cenpes / PDP / TE.