Foam Stimulation
Authors: Grundmann Steven R. , Lord David L. 
Published: December 2007

Summary
Foamed fluids are becoming very popular for use in stimulation treatments. This can be attributed to their excellent properties such as low leakoff rate, excellent proppant transport, longer fractures with less fluid, minimum formation damage, and superior posttreatment cleanup. Base fluids that can be foamed are oil, water. and acid.
Foam quality is very critical to many of the properties of the resultant foam fluid. This quality changes with temperature and pressure. Included in this paper is a new approach to an easier determination of foam quality under bottomhole treating conditions so that necessary ratio adjustment can be made at the wellhead to obtain the desired quality at the formation.

History
The earliest foam fracturing treatment was performed in Jan. 1968. 1 This treatment placed approximately 2041 kg (4,500 lbm) of 12-/20-mesh glass bead proppant with an approximately 83 to 85%-quality foam to stimulate the Brown shale formation in Lincoln County, WV. Virtually no other use of foam stimulation fluids was reported until the latter half of 1973. At this time, there was a development, undercurrent of foam stimulation use that spread across the country and into Canadian operations. Papers presented by Blauer, Mitchell, and Kohlhaas in April 1974 and by Blauer and Kohlhaas in October 1974 served further to popularize this budding stimulation technique.
Most foam fracturing treatments performed during 1973–76 were small volume, generally less than 189 m3 (50,000 gal), and carried some form of propping agent. Several other papers describing mechanical and design procedures for foam fracturing treatments appeared in 1975, 1976, and early 1977.
Surprisingly, the site of the first massive foam stimulation treatment was the same general location as the first experimental treatment. In June 1976, a 946-m 3 (250,000-gal) foam fracturing treatment, which placed 135 715 kg, (299,200 Ibm) total sand. was performed in Lincoln County, WV. A second treatment comprising 1060 m3 (280,000 gal) foam and 140 432 kg (309,600 Ibm) total sand was performed in Nov. 1976, in the same West Virginia county. Both treatments were conducted as part of a joint Columbia Gas System Service Corp./ERDA demonstration of massive hydraulic fracturing in the Devonian shale.
During, 1977–78, papers describing, variations in the established pattern in foam fracturing began to appear. Among these variations was extension of foam to fracture-acidizing applications. As a technique to reduce further the formation exposure to a potentially damaging aqueous fluid, a foamed methanol/water solution also was introduced at this time.
Although there was evidence that the number of foam stimulation treatments was increasing, papers presented during 1979–80 gave an impression that this service was entering a period of consolidation or maturity. Counteracting this initial impression were several massive hydraulic fracturing services performed in cast Texas during the latter half of 1980. Treatments with volumes ranging, up to 2233 m3 (590,000 gal) of 65%-quality foam were performed. This largest job to date placed 503 487 kg (1,110,000 total lbm) of sand.

Foam Quality
Foam is a gas/liquid dispersion, with gas as the internal phase and liquid as the external phase. Foam quality is the ratio of gas volume to foam volume (volumetric gas content) at a given pressure and temperature.
JPT
P. 597^