Title: Flow Properties and Drag-Reduction Characteristics of Surfactant-Based Fluids (SBF) in Large-Scale Coiled Tubing
Author(s): A. H. Ahmed Kamel, SPE, and S. N. Shah, SPE, University of Oklahoma
Presentation: 2008 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition held in The Woodlands, Texas, USA, 1–2 April 2008.
Abstract:
In spite of their wide use as friction reducer or fracturing fluid due to their unique characteristics, there is a very little information available in the literature about surfactant based fluids. Majority of this information is related to straight tubing with small sizes. Data of larger sizes as well as coiled tubing are very scarce. Furthermore, previous studies have correlated drag reduction behavior of these fluids only through simple power-law parameters. Little is known regarding the importance of elasticity on drag reduction of SBF. Scale-up factor is yet another problem.
This study aims at understanding the viscoelastic behavior of SBF and its effect on drag reduction in large-scale CT. The properties of widely used Aromox APA-T, a highly-active surfactant used as gelling agent in aqueous and brine base fluids, are investigated. Rheological and viscoelastic measurements are conducted for concentrations 1.5, 2, 3, and 4% vol. using Bohlin rheometer. Flow tests are conducted using ½- and 1½-in. CT with various curvature ratios. This study is the first investigation of flow behavior of SBF in a large-scale CT.
The results show that SBF exhibit a non-Newtonian pseudo-plastic behavior. Formation of rod-like micelles (emergence of viscoelasticity) is found to be affected by surfactant concentration and shear exerted on the fluid, which in turn, affects drag reduction characteristics. Also, simple correlations using only rheological properties may lead to erroneous results, especially when scaled-up to a large-scale.