High-Temperature Rheological Study of Foam Fracturing Fluids

Two significant observations were made during measurement of N/sub 2/ foam properties at temperatures up to 300/sup 0/F (149/sup 0/C) in a high-temperature, high-pressure recirculating loop viscometer: foam fluids did not thin as rapidly as gel fluids under similar conditions, so foams offer inherent advantages for high-temperature simulation work, and high gelling-agent concentrations do not improve dynamic foam stability; instead, high-temperature dynamic stability depends on surfactant type and concentration. Mathematical equations have been developed from experimental data to describe foam rheological behavior from 75 to 300/sup 0/F (24 to 149/sup 0/C), 0 to 80 quality, containing 0 to 80 lbm hydroxypropyl guar (HPG)/1,000 gal (0 to 9586 g HPG/m/sup 3/) in the aqueous phase. Basic physical properties previously outlined determined foam rheological behavior at 75/sup 0/F (24/sup 0/C). Foams were classified as yield-pseudoplastic-type fluids. This paper extends the previous work from 75 to 300/sup 0/F (24 to 149/sup 0/C) and covers a broader range of external liquid-phase compositions applicable to foam stimulation work.