The pumping of fracturing slurry through coiled and straight tubing can cause considerable wear of tubing and is an issue of industrial concern, both from safety and economic considerations. In hydraulic fracturing operations employing coiled tubing, the tubing wall is affected by non-uniform erosion for the section of the tubing spooled on the reel. The non-uniform wall erosion is caused by the centrifugal forces when pumping sand slurries at high rates. In spite of the large number of fracturing jobs performed in the industry today, research in this area of investigating and evaluating erosion has been limited.

This paper discusses the erosion phenomena and the mechanisms leading to the erosion process. The factors affecting erosion such as pump rate, slurry concentration, and fluid properties are investigated. Newtonian (water) and non-Newtonian (fracturing gel and slurry) fluids have been investigated. The results from the Computational Fluid Dynamics (CFD) simulations for the flow of these fluids in straight as well as coiled tubing are provided. The velocity profiles and sand concentration profiles for each case are presented which provide insight into the particle migration/segregation phenomenon associated with the erosion process. It is found that the fluid properties, flow velocity, and sand concentration all have major influence on the erosion process.

The future plans for the experimental study to understand the erosion in coiled tubing are also presented.

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