Title: Experimental and Simulation Study of Curvature Ratio Effects on Friction Pressure Loss in Coiled Tubing for Newtonian and Non-newtonian Fluids
Author(s): S. Jain, SPE, N. Singhal, SPE, and S.N. Shah, SPE, Well Construction Technology Center, The University of Oklahoma
Presentation: 2004 SPE Annual Technical Conference, Houston, TX
Abstract: Coiled tubing is widely used in the petroleum industry to pump fluids in the well bore at high rates. The friction pressure loss occurring in the tubing at these rates high enough to fracture the formation is an issue of immense concern to the industry. Most of this friction loss can be attributed to the section of the tubing reeled on the spool during the treatment. The size of the reel used in the treatment governs the degree of curvature of the tubing and in turn the corresponding pressure drop. These pressure losses apart from increasing the cost of the treatment due to increased energy requirements also reduce the life of the tubular used.
Experimental and simulation study has been undertaken to determine friction pressure loss in 1 1/2 & 2 3/8 inch coiled tubing using water and 35lb/Mgal Guar as test fluids. CFD software FLUENT has been used to generate simulations that have been validated with limited experimentation using a field scale test setup. Previous experiments used limited flow rates and few curvature ratios due to high field scale experimentation costs. But using CFD simulations friction pressure loss data has been generated for a range of curvature ratios and flow rates that are comparable to ones used in field.
Results obtained have been used to determine the effect of curvature ratio on the tubing size and fluid type used. Finally the optimum curvature ratio for the tubing sizes used has been determined.
The recommendations of optimum curvature ratio for various tubing sizes used are important as they will result in considerable saving in treatment cost due to reduced friction losses and also enhance life of tubular used.