Abstract:
Coiled Tubing (CT) services are one of the fastest growing oilfield technologies. There are 1881 CT units operating worldwide today compared to 1163 in 2005 (62% more). CT has been widely used in well drilling, wellbore cleanouts, stimulation, logging, perforation, and many other well interventions. The success of a treatment profoundly depends on the proper selection of fluids and their properties.  Even though fluids are widely used in all CT services, little attention has been paid to thoroughly test, evaluate, and understand the behavior of complex fluids.  In many instances the cause of an unsuccessful treatment is the failure of our understanding the true behavior of fluid.   
Fluid flow in CT is significantly different than straight pipe because of coiled tubing curvature and secondary flows it generates.  Fluids in CT experience a different level of shear and turbulent intensity.  It has been shown that fluids in CT exhibit significantly higher frictional pressure losses (up to 200%), less drag reduction, severe pipe erosion (with slurries), more fluid degradation due to shear, etc. when compared to straight pipe.  These characteristics are dependent on fluid type and concentration, CT size and dimensions, operating parameters such as temperature and pressure, shear rates, pH, salinity, density, and pipe roughness.  
The lecture will highlight recent research findings with several fluids and also present appropriate correlations for their proper hydraulics predictions. Case studies of wells recently fractured using CT will be provided to demonstrate the application of the correlations used in hydraulics calculations.  
Take Home Message: Fluid behavior in CT is more complex and significantly different than the straight pipe. This has a direct impact on the hydraulics/design of CT treatments.

Biography:
Subhash Shah is Stephenson Chair Professor in the School of Petroleum and Geological Engineering and also the Director of Well Construction Technology Center, University of Oklahoma. Dr. Shah has 35 years of distinguished career with the oil and gas industry – 18 years in industry and 17 years in academics. Dr. Shah holds B.S., M.S., and Ph.D. degrees, all in chemical engineering. He has authored 250 technical papers and two chapters in books. Dr. Shah’s expertise is in the area of non-Newtonian fluid mechanics to better understand the flow behavior and rheological characterization of complex fracturing, drilling, and completion fluids. Dr. Shah has initiated and successfully managed for 14 years a joint-industry consortium on the Coiled Tubing.  He is on the Editorial Board of SPE and is a recipient of Mid-Continent North America Region “Completions Optimization and Technology” award.  Dr. Shah served as Director (2002-04) on the Board of International Coiled Tubing Association (ICoTA).  He is a licensed professional engineer in the State of Oklahoma.