Foam property requirements for proper hole cleaning while drilling horizontal wells in underbalanced conditions

This paper summarizes an extensive experimental program to determine effective foam drilling conditions in horizontal wells. The program included foaming-agent selection (considering optimum concentration and salt/oil contaminants), rheological characterization of foams, development of a flow loop to test the foam-carrying capacity in high-angle wells, definition of the test procedure and matrix, and analysis of the results. After 60 bed tests were performed at a cuttings-transport flow loop, correlations were proposed to predict the cuttings-bed erosion capacity in horizontal wells as functions of the foam quality and the mixture's Reynolds number.