Rheological Properties and Frictional Pressure Loss of Drilling, Completion, and Stimulation Fluids in Coiled Tubing

2004 ◽  
Vol 126 (2) ◽  
pp. 153-161 ◽  
Author(s):  
Yunxu Zhou ◽  
Subhash N. Shah

The rheological properties and friction pressure losses of several common well-drilling, completion, and stimulation fluids have been investigated experimentally. These fluids include polymeric fluids—Xanthan gum, partially hydrolyzed polyacrylamide (PHPA), guar gum, and hydroxyethyl cellulose (HEC), bentonite drilling mud, oil-based drilling mud, and guar-based fracturing slurries. Rheological measurements using a Bohlin CS 50 rheometer and a model 35 Fann viscometer showed that these fluids exhibit shear thinning and thermal thinning behavior except the bentonite drilling mud whose viscosity increased as the temperature was raised. Flow experiments using a full-scale coiled tubing test facility showed that the friction pressure loss in coiled tubing is significantly higher than in straight tubing. Since the polymeric fluids displayed drag reducing property, their drag reduction behavior in straight and coiled tubings was analyzed and compared. Plots of drag reduction vs. generalized Reynolds number indicate that the drag reduction in coiled tubing was not affected by polymer concentration as much as in straight tubing. The onsets of turbulence and drag reduction in coiled tubing were significantly delayed as compared with straight tubing. The effect of solids content on the friction pressure losses in coiled tubing is also briefly discussed.

2002 ◽  
Author(s):  
Y. Zhou ◽  
S. N. Shah

The rheological properties and friction pressure losses of several fluids that are most commonly used as well drilling, completion, and stimulation fluids have been investigated experimentally. These fluids include polymeric fluids – Xanthan gum, partially hydrolyzed polyacrylamide (PHPA), guar gum, and hydroxyethyl cellulose (HEC), bentonite drilling mud, oil-based drilling mud, and guar-based fracturing slurries. Rheological measurements using a Bohlin CS 50 rheometer and a model 35 Fann viscometer showed that these fluids exhibit shear thinning and thermal thinning behavior except the bentonite drilling mud whose viscosity increased as the temperature was raised. Flow experiments using a full-scale coiled tubing test facility showed that the friction pressure loss in coiled tubing is significantly higher than in straight tubing. Since the polymeric fluids displayed drag reducing property, their drag reduction behavior in straight and coiled tubings was analyzed and compared. It was found that the drag reduction (DR) in coiled tubing is much lower than that in straight tubing. Plots of drag reduction vs. generalized Reynolds number indicate that the drag reduction in coiled tubing was not affected by polymer concentration as much as in straight tubing. The onsets of turbulence and drag reduction in coiled tubing were significantly delayed as compared with straight tubing. The effect of solids content on the friction pressure losses in coiled tubing is also briefly discussed.


2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Arild Saasen

Controlling the annular frictional pressure losses is important in order to drill safely with overpressure without fracturing the formation. To predict these pressure losses, however, is not straightforward. First of all, the pressure losses depend on the annulus eccentricity. Moving the drillstring to the wall generates a wider flow channel in part of the annulus which reduces the frictional pressure losses significantly. The drillstring motion itself also affects the pressure loss significantly. The drillstring rotation, even for fairly small rotation rates, creates unstable flow and sometimes turbulence in the annulus even without axial flow. Transversal motion of the drillstring creates vortices that destabilize the flow. Consequently, the annular frictional pressure loss is increased even though the drilling fluid becomes thinner because of added shear rate. Naturally, the rheological properties of the drilling fluid play an important role. These rheological properties include more properties than the viscosity as measured by API procedures. It is impossible to use the same frictional pressure loss model for water based and oil based drilling fluids even if their viscosity profile is equal because of the different ways these fluids build viscosity. Water based drilling fluids are normally constructed as a polymer solution while the oil based are combinations of emulsions and dispersions. Furthermore, within both water based and oil based drilling fluids there are functional differences. These differences may be sufficiently large to require different models for two water based drilling fluids built with different types of polymers. In addition to these phenomena washouts and tool joints will create localised pressure losses. These localised pressure losses will again be coupled with the rheological properties of the drilling fluids. In this paper, all the above mentioned phenomena and their consequences for annular pressure losses will be discussed in detail. North Sea field data is used as an example. It is not straightforward to build general annular pressure loss models. This argument is based on flow stability analysis and the consequences of using drilling fluids with different rheological properties. These different rheological properties include shear dependent viscosity, elongational viscosity and other viscoelastic properties.


2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Subhash N. Shah ◽  
Yunxu Zhou

This study experimentally investigates the drag reduction characteristics of the most commonly used polymer fluids in coiled tubing applications. The flow loop employed consists of 12.7mm straight and coiled tubing sections. The curvature ratio (a∕R, where a and R are the radii of the tubing and the reel drum, respectively) investigated is from 0.01 to 0.076, which covers the typical curvature ratio range encountered in the oil and gas industry applications. Fluids tested include xanthan gum, guar gum, and hydroxypropyl guar at various polymer concentrations. It is found that the drag reduction in coiled tubing is significantly lower than that in straight tubing, probably due to the effect of secondary flow in curved geometry. The onset of drag reduction is also found to be delayed as the curvature ratio was increased. A correlation for the maximum drag reduction (MDR) asymptote in coiled tubing is developed. When the curvature ratio is set to zero, the new correlation reduces to the well-known Virk’s MDR asymptote for dilute polymer solutions in straight pipes. A new drag reduction envelope is proposed for the analysis of drag reduction behavior of polymeric fluids in coiled tubing. Application of the new drag reduction envelope is also discussed.


2020 ◽  
Vol 26 (2) ◽  
pp. 57-69
Author(s):  
Hassan Abdul Ameer ◽  
Hassan Abdul Hadi

    In this work, calculation of pressure losses in circulating system for two drilling muds is evaluated in Noor oil field. Two types of drilling muds that were used for drilling section 12 1/4" and 8 3/4" which are Salt saturated mud and Ferro Chrome Lignosulfonate-Chrome Lignite mud. These calculations are based on field data that were gathered from the drilling site of well Noor-15, which are included, rheological data, flow data and specification of drill string. Based on the obtained results, the best rheological model that fit their data is the Herschel-Bulkley model according to correlation coefficient value for their two drilling mud. Also, the difference between the calculated pressure loss by Herschel-Bulkley model and standpipe pressure value are very convergence.


1983 ◽  
Vol 23 (01) ◽  
pp. 11-20 ◽  
Author(s):  
Syed M. Hussaini ◽  
Jamal J. Azar

Abstract Experiments are conducted with actual drilling muds to study the behavior of drilled cuttings in a vertical annulus. The effect of parameters such as particle size, flow rate, apparent viscosity, and yield point to plastic viscosity ratio on mud-carrying capacity are studied. The applicability of a semiempirical transport model developed by Zeidler also is investigated. It has been shown that in vertical annuluses, the fluid annular velocity has a major effect on the carrying capacity of muds, while the other parameters have an effect only at low to medium fluid annular velocities. We also conclude that Zeidler's semiempirical formulations for the prediction of drilled cuttings behavior are valid with certain limitations. Introduction One of the most important functions of a drilling fluid is to transpose the drilled particles (cuttings) generated by the drill bit to the surface through the wellbore annulus. This commonly is called the "carrying capacity" of drilling mud. Factors affecting the ability of drilling muds to lift cuttings arefluid rheological properties and flow rate,particle settling velocities,particle size and size distribution, geometry, orientation, and concentration,penetration rate of drill bits,rotary speed of drillstring,fluid density.annulus inclination, anddrillpipe position in the wellbore (eccentricity) and axially varying flow geometry. With the advent of deeper drilling and better bit designs, the demand for expending most of the energy at the bit has made it necessary to minimize the pressure losses in the annulus. These pressure losses depend on the fluid velocity, fluid density, and particle concentration. By control of these factors, pressure losses can be minimized. The particle slip velocity is an important factor and is defined as the velocity at which a particle tends to settle in a fluid because of is own weight. The velocity depends on the particle size, its geometry, its specific weight, and fluid rheological properties. The carrying capacity of muds also is affected by the velocity profile in the annulus. With all these variables acting simultaneously, the determination of carrying capacity of a mud becomes a complicated problem. An optimal drilling fluid is expected to lift the cuttings from the wellbore, suspend them when circulation is stopped, and drop them at the surface. Failure to achieve this performance often leads to problems that are costly and performance often leads to problems that are costly and time-consuming to solve. To avoid such problems, the previously mentioned parameters are to be considered in previously mentioned parameters are to be considered in the design of an optimal drilling fluid. Previous Investigations Previous Investigations SPEJ P. 11


2013 ◽  
Vol 746 ◽  
pp. 515-519
Author(s):  
Dan Qiong Li ◽  
Shi Cheng Zhang ◽  
Suian Zhang

A coiled tubing pressure loss prediction model was established by fluid dynamics theory and method which based on the basic characteristics of the non-Newtonian fluid rheology; Construction displacement, sand ratio and well depth parameters of the pressure loss in the pipe, and calculated pipe pressure loss when the actual pumping process through examples. Thesis proposes: (1) the bend within the pressure loss is an important part of the pressure loss, should be based on the construction object to choice coiled tubing length reasonable, and minimize elbow paragraph length in order to reduce the pipe friction pressure loss. (2) Flow and sand ratio have the same impact of the law with the depth changes in the pressure loss of the straight pipe segment and elbow segment, increases linearly with the depth, flow or sand ratio the larger, more dramatic increase with the depth. Flow or sand ratio the larger the total pressure loss of the tube with the depth decreasing amplitude the greater. (3) According to the actual pump injection procedure, the tube fluid rheological parameters will change, inject pre-flush and replacement fluid the pipe pressure loss low; inject sand mixing liquid friction pressure loss high.


Author(s):  
Ahmed H. Kamel

This study involves experimental investigation of rheological and hydraulic characteristics of aqueous based polymeric and surfactant fluids in straight and coiled tubing. The fluids matrix includes guar, HPG, PHPA, welan, xanthan, and surfactant. Bohlin rheometer was used to evaluate rheological and viscoelastic characteristics. For hydraulic characteristics, small- and large-scale flow loops were used. It is observed that all fluids exhibit comparable non-Newtonian behavior and improved viscous and elastic properties. Among polymeric fluids, guar and welan provide better viscosity and suspension properties. Surfactant is significantly affected by the formation of rod-like micelles and other microstructures. Master curves for rheological and elastic properties are developed using the molecular theory approach. The foremost benefit of these curves is its dimensionless form that provides a unique technique to predict viscosity for all fluids. For hydraulic properties, friction losses in coiled tubing are significantly higher than in straight tubing due to centrifugal forces and secondary flows. Surfactant is more sensitive to shear field applied where different microstructures are induced and thus they exhibit better drag reduction characteristics than polymeric fluids especially in coiled tubing with larger sizes. However, in straight tubing, guar shows better drag reduction characteristics than surfactant and other polymers, which diminishes as tubing size increases. However, welan gum exhibits a comparable performance. Overall, all fluids are considered good candidates as fracturing fluids with specific features for each. Unique characteristics of each fluid is discussed and explained in more details within the context of the present paper.


2005 ◽  
Author(s):  
Parag Vijay Gujar ◽  
Subhash Nandlal Shah ◽  
Yunxu Zhou

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