Correlations To Predict Frictional Pressure Loss of Hydraulic-Fracturing Slurry in Coiled Tubing

Abstract

Compared with conventional-tubing fracturing, coiled-tubing (CT) fracturing has several advantages. CT fracturing has become an effective stimulation technique for multizone oil and gas wells. It is also an attractive production-enhancement method for multiseam coalbed-methane wells, and wells with bypassed zones. The excessive frictional pressure loss through CT has been a concern in fracturing. The small diameter of the string limits the cross-sectional area open to flow. Furthermore, the tubing curvature causes secondary flow and results in extra flow resistance. This increased frictional pressure loss results in high surface pumping pressure. The maximum possible pump rate and sand concentration, therefore, have to be reduced. To design a CT fracturing job properly, it is essential to predict the frictional pressure loss through the tubing accurately.This paper presents correlations for the prediction of frictional pressure loss of fracturing slurries in straight tubing and CT. They are developed on the basis of full-scale slurry-flow tests with 1½-in. CT and slurries prepared with 35 lbm/1,000 gal of guar gel. The extensive experiments were conducted at the full-scale CT-flow test facility. The proposed correlations have been verified with the experimental data and actual field CT-fracturing data. Case studies of wells recently fractured are provided to demonstrate the application of the correlations. The correlations will be useful to the CT engineers in their hydraulics design calculations.

Analysis of Circulating System Frictional Pressure Loss in Microhole Drilling with Coiled Tubing

“…Suppose the discriminant factors C 1 and C 2 are described in Eq. 5, by comparing Re with C 1 and C 2 , different flow regimes of power-law fluid can be estimated and their corresponding Fanning friction factors [10] can be expressed as follows:…”

“…Willingham and S. N. Shah [8] researched the DFCFPL of Newtonian fluid and non-Newtonian fluid in CT in reel and vertical well section. From 2001, Subhash N. [9,10] studied the impact of drilling cuttings on DFCFPL and predicted the DFCFPL in CT fracturing process. B. N. Rao, Y. Zhou and S.N.…”

Analysis of Drilling Fluid Circulating Pressure Loss in Hole Annulus for Microhole Drilling

“…Walton et al [5] designed the hydraulic pressure of CT drilling, and McCann [6] studied the CPL of turbulent fluid in CT. Azouz and Shah [7] conducted experiment researches CPL in CT. Medjani and Shah [8] predicted the CPL of non-Newtonian fluid in CT. Willingham and Shah [9] studied the CPL of Newtonian fluid and non-Newtonian fluid in CT in vertical well section and reel. Shah [10,11] studied the influence of cuttings on CPL and predicted the fracturing CPL in CT. Rao [12,13] studied the impact factors of frictional CPL for non-Newtonian fluid in CT. Ma Dongjun [14] studied a model of calculating the CPL in coiled tubing ultrashort radius radial drilling. Hou Xuejun [15] analyzed the flow resistance in coiled tubing wound around a reel in microhole drilling.…”