Flow tests of the Gladys McCall well

This report pulls together the data from all of the geopressured-geothermal field research conducted at the Gladys McCall well. The well produced geopressured brine containing dissolved natural gas from the Lower Miocene sands at a depth of 15,150 to 16,650 feet. More than 25 million barrels of brine and 727 million standard cubic feet of natural gas were produced in a series of flow tests between December 1982 and October 1987 at various brine flow rates up to 28,000 barrels per day. Initial short-term flow tests for the Number 9 Sand found the permeability to be 67 to 85 md (millidarcies) for a brine volume of 85 to 170 million barrels. Initial short-term flow tests for the Number 8 Sand found a permeability of 113 to 132 md for a reservoir volume of 430 to 550 million barrels of brine. The long-term flow and buildup test of the Number 8 Sand found that the high-permeability reservoir connected to the wellbore (measured by the short-term flow test) was connected to a much larger, low-permeability reservoir. Numerical simulation of the flow and buildup tests required this large connected reservoir to have a volume of about 8 billion barrels (two cubic miles ofmore » reservoir rock) with effective permeabilities in the range of 0.2 to 20 md. Calcium carbonate scale formation in the well tubing and separator equipment was a problem. During the first 2 years of production, scale formation was prevented in the surface equipment by injection of an inhibitor upstream of the choke. Starting in 1985, scale formation in the production tubing was successfully prevented by injecting inhibitor pills'' directly into the reservoir. Corrosion and/or erosion of surface piping and equipment, as well as disposal well tubing, was also significant.« less