ABSTRACT

An exploration and production off-shore transport system was hydraulically analyzed to determine its current transport capabilities and assess the effect of a possible change in the properties of the transported crude oil. This system is a complex interconnected platform network where different crude oils are mixed and pumped into various pipelines. In addition, water cuts and API values vary based on the field that is being produced. A dramatic change of the crude oil quality and API is expected within the next few years. Therefore, the existing booster system will require upgrades and modifications to handle the new operating conditions while the crude oil production is being increased. As a part of the hydraulic analysis, a performance testing of the existing equipment was required to estimate machine degradation and efficiencies which will help to optimize the system operation. However, due to the complexity of the system operation, it was very critical to determine precisely the machine configuration and flow conditions required to conduct the test. Thus, a detailed and rigorous planning of the testing was required to ensure that the correct operating conditions were available during the tests; therefore, the measurement of the required flow balances from different production platforms were scheduled in advance.

Consequently, a detailed evaluation of the pumping system was conducted in order to estimate the required flow balance, machine configuration, and fluid distribution throughout the entire system for different fluid properties and mixtures since exact compositions vary on a daily basis. This evaluation included a hydraulic simulation of the pumping and pipeline system and it was focused on determining the inlet flow conditions required at the platform and its distribution through the different machines taking into account the system minimum pressure and flow constraints. Since the centrifugal machines do not have a flow control valve to accurately distribute the flow, it is balanced by varying the speed of another machine while the tested machine stays at constant speed which requires an exact configuration of the ten available machines. The performance test was planned to comply with the ASME code while pump performance curves were corrected by viscosity based on the ANSI/HI 9.6.7-2004 standard. Thus, a good range of machine flow can be swept for a single speed. This paper presents the methodology used in the assessments as well as the results obtained for the steady state and transient cases. In addition, a comparison between the conditions used for the real test and the simulation is presented.

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