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Experimental investigation of cuttings transport in horizontal wells using aerated drilling fluid

Gül, Sercan
A new experimental approach has been introduced in this thesis for the cuttings transport in horizontal wellbores with the introduction of drag reducers into the aerated drilling fluids. Advanced Flow Loop System (annular test section of 21 ft. long 2.91-in. ID transparent casing and 1.85 in. OD inner drill pipe) in Middle East Technical University Petroleum and Natural Gas Engineering Department have been used for the experiments. The liquid phase has been water and water-PHPA copolymer mixture where the gaseous phase has been dried air. Water and water-polymer mixture experiments have been conducted in 0.05%V/V, 0.07%V/V, and 0.10% V/V PHPA polymer concentrations. It was observed that optimum concentration of PHPA polymers in water for the given experimental test section is 0.07% with average drag reduction of 41.88% in single phase flow. Moreover, increasing water and gas flow rates increases the differential pressures. Four main flow regimes were observed in the experiments which are a bubble, elongated bubble, slug and wavy annular. It was also observed that adding PHPA polymers in water shifts the flow regime transition boundaries to higher y values and water is the main phase in cuttings transport. Effect of increasing gas velocities is much lower compared with the effect of increasing liquid velocities in cuttings transport. Using PHPA polymers in 0.07% reduced the cuttings area by an average of %4.05 while reducing the differential pressures by an average of %23.90 with the existence of cuttings at the rate of penetration of 115 ft./hr.