The 29D Monarch & 10-10 pool is located 2½ mi. southeast of Taft, California, in the "29D" area of the Midway-Sunset field. Although surrounded by wells in an old producing area, the pool remained undiscovered until December, 1962.

Closure is not present in the uppermost upper Miocene beds on the 29D portion of the Spellacy anticline, but westward thickening of deeper sediments provides localized structural reversal and closure in the Monarch and 10-10 sandstones.

As a result of the pool discovery, seven significant phenomena were noted: (1) long interval tests recovered only strong gas blows in intermingled gas, oil, and water zones; (2) 1,000 feet of productive interval were found in a gross sandstone body having less than 200 feet of structural closure; (3) 10 ft. or less of shale was sufficient to form vertical barriers; (4) a natural boundary within the gross sandstone body separates the Monarch and 10-10 intervals; (5) tilted oil-water interfaces were found in all reservoirs; (6) a 1 ohm-meter increase in resistivity over that of a wet sandstone may indicate clean oil sandstone; (7) comparison of sonic logs before and after testing may show intervals of gas entry in an oil and gas sequence when only gas is recovered.

Cumulative production through March, 1964, exceeds 2,000,000 barrels of 32° API oil and gas equivalents. Daily production approaches 9,000 barrels from 32 flowing wells having an average total depth of 4,700 ft.

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