Abstract

The Madden Deep Unit #2-3 Bighorn well is located in the NW SE of Section 3, T38N, R90W, in Fremont County, Wyoming on the crest of the Madden Anticline. This well spudded December 19, 1986, and reached a total depth of 24,250 feet fifteen months later, on March 20, 1988. Three strings of casing and four liners were run, ranging in size from 30 inches set at 1,501 feet to 5 inches set at 24,247 feet. The well was perforated and acidized from 23,579-23,852 feet and completed for 38 MMCFGPD from the Mississippian Madison Limestone.

Six cores were cut while drilling the #2-3 Bighorn; 2 Frontier, 1 Phosphoria, 1 Tensleep and 2 Madison. The Madison was cored from 23,695-23,734 feet, and from 23,749-23,770 feet. Porosities from core analyses ranged from 3-17% within the perforated interval, and averaged 7%.

The Bighorn #2-3 is only the second well to test the Paleozoic section on the prolific eastwest-trending Madden Anticline. The initial deeper pool discovery well, the MDU #1-5 Bighorn drilled 2.5 miles to the west, was also completed in the Madison for 20 MMCFGPD in August, 1985. Madison gas in the Madden Anticline contains 12% H₂S and will therefore require processing facilities to be constructed before it can be marketed.