Title: DETERMINATION OF FRICTION PRESSURE LOSSES IN STRAIGHT AND COILED TUBING BY CFD SIMULATIONS
Author(s): S. Shah PhD., N. Singhal and S. Jain, Mewbourne School of Petroleum and Geological Engineering, The University of Oklahoma
Presentation: AIAA / ASME symposium
Location: Oklahoma City, OK
Date: Feb. 2004
Abstract:
Friction pressure losses in straight and coiled tubing while pumping fluid have been an area of interest for the oil industry. The determination of these losses is necessary for the success of the fracturing jobs as they determine the surface pumping pressures. There is also a need to minimize these losses as they result in higher job costs due to increased horsepower requirements. The complex flow geometry and fluid behavior limit the amount of theoretical and analytical research performed in this field. The available studies are assuming simplified conditions and hold little practical significance. On the other hand there has been a lot of experimental research conducted to minimize these losses and determine their magnitudes with accuracy. The costs associated with these types of experiments limits the amount of research performed.
Computational Fluid Dynamics (CFD) is a powerful tool to evaluate these friction losses with accuracy and conduct research to minimize these losses without entailing significant costs. Moreover, through CFD the secondary flow effects and other flow characteristics can be visualized to aid in the better understanding of the flow phenomenon and apply it to improve flow characteristics. This study uses FLUENT a powerful CFD software to analyze the behavior of flow of fluids in coiled tubing. A 3-dimensional model of the coiled and straight tubing geometry has been constructed in Gambit. The coiled tubing model due to complex geometry has been meshed with unstructured grid elements, hexahedral wedges have been used as mesh elements and cooper meshing scheme is used to mesh the entire geometry. The boundary conditions applied are velocity inlet, outflow and wall. The meshed geometry was exported to FLUENT, which is the solver in the present case. K-e? model has been used for modeling turbulence.
This study includes the results obtained while pumping Newtonian and Non-Newtonian fluids. Various results obtained have been compared with experimental results, and standard correlations. The study also demonstrates the significant increase in pressure losses that occurs due to tubing curvature.
