Date

2018

Author

Gürçay, Kazım Onur

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Accurate estimation of friction pressure loss through annulus is important to avoid lost circulation, pipe sticking, kicks or more serious problems in drilling and well completion operations. Several studies have been performed to determine friction pressure loss experimentally and theoretically through pipe and annulus with the effects of eccentricity, pipe rotation, annulus geometry or flow regime by applying several rheological models. However, in addition to all of these factors, fluid rheology is dependent on temperature. Change in rheological properties of fluid also leads to shift in friction pressure loss. However, experimental studies about the effect of temperature on friction pressure loss for the flow of non-Newtonian fluids have not been conducted. This study experimentally investigated the effect of temperature on friction pressure loss through vertical concentric annulus (2.91 in X 1.85 in) with a polymerized drilling fluid including Polyanionic Cellulose (0.50 lb/bbl) and Xanthan Gum (0.75 lb/bbl). Friction pressure loss was determined with Herschel-Bulkley rheological model which has less error than Bingham Plastic and Power Law rheological models by comparing measured and calculated shear stresses with four different equivalent diameter concepts. Also, the most suitable equivalent diameter concept was chosen as hydraulic radius in laminar region, slot approximation in turbulent region by comparing experimental and theoretical results of friction pressure loss and flow rate. Temperature effects on rheological parameters, Reynolds number and apparent viscosity were investigated. Among rheological parameters, consistency index (K) and yield point (YP) were more sensitive to the effect of temperature than flow behavior index (n). Reynolds number and apparent viscosity vs. temperature plots with flow rates changing from 25 to 125 gpm were examined and it was observed that high shear rate significantly influenced Reynolds number with increasing temperature. Apparent viscosity also decreased significantly by increasing temperature at low shear rates. Also, transition from laminar to turbulent flow regime was accelerated by increasing temperature. As a result, these parameters were affected by temperature and thus, this led to a change in friction pressure loss and regime transition directly. This study is the starting point of investigation of the effect of temperature on non-Newtonian fluids. It will lead to future investigations for modeling temperature effect on friction pressure loss with considering real drilling conditions including eccentricity, inclination and inner pipe rotation.

Subject Keywords

Non-Newtonian fluids., Drilling muds., Rheology., Friction.

URI

http://etd.lib.metu.edu.tr/upload/12622633/index.pdf
https://hdl.handle.net/11511/27510

Collections

Graduate School of Natural and Applied Sciences, Thesis