Significant circulating system pressure losses occur between mud and extreme long drill pipes during deep or ultra deep offshore drilling operations with the available fluid circulation technology. Therefore high pump horsepower is required to circulate the mud. Addition of a small amount of frictional drag reducer can decrease these circulating system pressure losses significantly. As a result, pipe flow capacity can be increased with lower horsepower requirements. Frictional drag reducing polymers are often composed of high molecular weight linear molecules and can be used with water or hydrocarbon based solvents.

The performance of a liquid polymer emulsion which contains partially hydrolyzed polyacrylamide/polyacrylate (PHPA) copolymer was studied in this paper. Straight cylindrical pipe flow experiments were performed at different concentrations of solutions for measuring frictional pressure losses. Measured and theoretical frictional pressure loss values shows that as the "PHPA" concentration increases, considerable drag reduction (as high as 60 %) can be obtained. The optimum concentration for drag reduction purposes was estimated as 0.0020 (v/v). A new friction factor is proposed as a function of "PHPA" concentration and Reynolds number, and the results showed that the pressure losses can be estimated with an error less than 15 % by using the developed friction factor.

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