Session: 11-07-01 Petroleum Production: Offshore Systems and Subsea Operations

Submission Number: 176434

Water Accumulation and Removal During Shutdowns and Restarts in Oil Pipelines: Comparative Analysis Between Experiments and Commercial Simulators 

Offshore oil transportation in long pipelines involves the simultaneous presence of different phases, such as gas, oil, and water. Their flow is strongly influenced by seabed topography and by transient production events, such as shutdown and restart processes. These events may cause phase separation and remixing, leading to flow assurance challenges such as corrosion, emulsion formation, and hydrate deposition. In this context, the objective of this work is to investigate the accumulation of free water during shutdown and its subsequent removal during restart.

A matrix of transient three-phase gas–oil–water experiments is conducted in a newly developed flow loop at CEPETRO-UNICAMP in Brazil. The loop is 100 meters long and 3 inches in diameter, with horizontal sections and inclined sections, both upward and downward. The facility is fully instrumented with flow, pressure, and temperature sensors, in addition to high-speed cameras that enable flow visualization and volume fraction measurements. Compressed air is used to represent the gas phase, while a low-viscosity mineral oil represents the hydrocarbon liquid phase. The dimensions of the flow loop and the properties of the mineral oil ensure similarity between the laboratory scale and the real scale of a Brazilian pre-salt oil well selected as reference.

In parallel with the experiments, one-dimensional simulations using commercial software are performed under the same operating conditions. The simulations adopt the same geometry and working fluids as the experiments. The most relevant data obtained from both experimental and computational approaches include flow patterns, accumulated water volume after shutdown, and the time required for complete water removal during restart. These datasets enable a direct comparison between experimental results and computational predictions. The analysis focuses on identifying the main variables that accelerate or delay water removal, with special emphasis on the effect of oil and gas flow rates, and therefore their superficial velocities.

The results reveal discrepancies between experimental measurements and predictions from commercial simulators. Differences are also observed among the simulators themselves, due to the specific mathematical models and equations implemented in their codes. Nevertheless, a general trend is identified: higher oil and/or gas flow rates lead to faster water removal during restart. The functional forms of these relationships will be further analyzed in the full paper, where the complete set of comparisons and results will be presented in greater detail. The differences identified between experimental and computational approaches provide valuable insights. They highlight possible directions for improving commercial simulators and offer guidelines for safer and more efficient shutdowns and restarts in oil production and transportation.

Presenting Author: Rodolfo Marcilli Perissinotto Center for Energy and Petroleum Studies - University of Campinas

Presenting Author Biography: Rodolfo Perissinotto is a research scientist in the Artificial Lift Flow Assurance (ALFA) research group, with activities in the Center for Energy and Petroleum Studies (CEPETRO) at the University of Campinas (UNICAMP), in Brazil. The researcher has been working since 2015 in the field of mechanical and petroleum engineering with focus on fluid mechanics, mainly the topics of multiphase flow, artificial lift, and flow assurance.

Rodolfo holds a Ph.D. in mechanical engineering with an emphasis on thermal and fluids. Currently, he is a member of a research project in Brazil dedicated to studying transient three-phase flows in long pipelines. The researcher has published 11 journal papers and 20 conference papers in related areas, with 290 citations, since 2019.

https://www.linkedin.com/in/rodolfoperissinotto

Authors:

Rodolfo Marcilli Perissinotto Center for Energy and Petroleum Studies - University of Campinas
Ana Carolina P. Roque School of Mechanical Engineering (FEM) - UNICAMP
Jaqueline Diniz Da Silva Center for Energy and Petroleum Studies (CEPETRO) - UNICAMP
Daniely Amorim Das Neves Center for Energy and Petroleum Studies (CEPETRO) - UNICAMP
Juliana Rangel Cenzi Center for Energy and Petroleum Studies (CEPETRO) - UNICAMP
William Monte Verde Center for Energy and Petroleum Studies (CEPETRO) - UNICAMP
Marcelo Souza De Castro Center for Energy and Petroleum Studies (CEPETRO) - UNICAMP