Study Investigates Foam Use for Control of Pipeline Slugging
Authors: Carpenter Chris 
Published: December 2022

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22235, “Foams To Control Slugging Issues in Pipelines—From Laboratory to Simulation,” by Ivy C.C. Hsia, Bishop Falope, and Nor Hadhirah Halim, Petronas, et al. The paper has not been peer reviewed. Copyright 2022 International Petroleum Technology Conference. Reproduced by permission.

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In one of the operator’s Malaysian fields, hydrodynamic slugging, or two-phase liquid/gas flow instability in the pipeline, has caused losses in flow capacity and intense vibration at the separator, leading to integrity issues. To understand how the behavior of foams in a pipeline affect or alleviate slugging performances, foam behavior was simulated using the OLGA (short for “oil and gas”) simulator, a commercial dynamic multiphase-flow-simulation software. This study showed that foams were able to slow gas velocity and diminish liquid fluctuations, thus reducing slugging in a problematic pipeline.

Challenges Posed by Slugging
Hydrodynamic slugging or instability of waves at certain liquid/gas flow rates in the pipeline were concerns in several fields in Malaysia. In one such field, almost 50% of the loss in flow capacity (i.e., liquid holdup) from a producing pipeline was the result of slugging, causing gas-production deferments of as much as 30 million scf/D. Severe vibrations from the pipeline to the separator often were felt at the platform, leading to questions about the mechanical integrity of the separator and anticipated high maintenance costs.
The issues of slugging can be solved with the use of foams introduced into the pipeline to slow down gas velocity and enhance mixture with liquid. Foam injection into the wellbore has proved to act as a flow stabilizer, thus removing the slugging in the well and improving gas lift. Foams from surfactant injection increase the viscosity of gas, thus reducing gas movement and velocity but with a pressure penalty. Surfactant concentration also decreases the liquid’s surface tension to a minimum value reached when micelles start to form, called the critical micelle concentration (CMC). A thorough understanding of reduction of liquid surface tension is critical. The inclusion of crude oil into the authors’ laboratory tests is intended to establish the actual performance of the surfactant and the effect of crude oil on viscosity and interfacial tension (IFT) to replicate actual fluid properties (i.e., water cut and emulsion tendencies of the field).
The software used simulates flow under actual pipeline conditions. A base model was built to establish slugging conditions using parameters obtained from the field. The model was modified to include input parameters of foams such as viscosity and IFT between two phases to determine if they can suppress foams; this was achieved by reading changes in the total liquid volume flow coming from the pipeline throughout the extent of the pipeline. In the complete paper, the authors sought to understand how to determine foam viscosity and interfacial tension in the presence of crude oil using precision laboratory instrumentation and then used these measurements as inputs into the simulation software to calculate the percent reduction in liquid flow volume and fluctuations of an actual pipeline facing slugging issues.