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PHPA as a frictional pressure loss reducer and its pressure loss estimation

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2007
Ercan, Can
As the demand of oil and gas is increasing, using the existing reservoirs more efficiently as well as searching for new reservoirs is mandatory. Most undiscovered reservoirs are in deep or ultra-deep offshore locations, where drilling to such targets are very difficult with the available fluid circulation technology, since there exists a significant frictional pressure loss due to extreme long wellbores. In order to reduce the frictional pressure losses inside the drillstring, frictional drag reducers are used. Frictional drag reducers are mostly high molecular weight linear polymer molecules and can be used with water or hydrocarbon based solvents. The system used in this study is Baroid EZ-Mud water solutions. Baroid EZ-Mud is a liquid polymer emulsion containing partially hydrolyzed polyacrylamide / polyacrylate (PHPA) co-polymer. This study aims to observe the performance of EZ-Mud as a frictional drag reducer. For this purpose, a flow loop that consisted of a circular pipe where the frictional pressure losses can be observed under various flow rates and concentrations is developed. Pipe flow experiments were performed using water-based mud generated using different concentrations of Baroid EZ-Mud at different flow rates. Differential pressure values were recorded for each run. Rheological properties of each mud sample were determined using Fann (Couette) viscometer in order to determine the theoretical frictional pressure losses. Theoretical and measured frictional pressure losses were compared. Results showed that, as the concentration of EZ-Mud was increased, considerable frictional drag reduction as high as 60% was observed. Based on the experimental data obtained from the flow loop using EZ-Mud with different concentrations, a friction factor correlation as a function of Reynolds Number and EZ-Mud concentration is developed. The proposed correlation performance was also compared with the existing correlations from the literature. It has been observed that, frictional pressure losses using the developed friction factor could be estimated within an error range of maximum 15 %, whereas, the existing models could not predict frictional pressure losses as accurate as the proposed model.