Abstract: Block 16 Field, Ward County, Texas

Richard N. Mercurio, Lawrence E. Monley

Block 16, located on the eastern flank of the Delaware basin, is one of the more prolific fields of the deep Paleozoic gas play in the basin. Primary producing reservoirs are the Devonian chert and Lower Ordovician-Ellenburger dolomite.

The field is an anticlinal trap with closure extending 9 mi (14 km) northwest and 3 mi (5 km) northeast. The structure is asymmetrical toward the southwest with 1,500 ft (455 m) of closure. Demonstrable structural growth dates from early Strawnian (Pennsylvanian) into Wolfcampian (Permian). Structural terracing occurs on younger Permian data horizons.

The discovery well was completed in 1968. At present the field is nearing final definition with 22 gas-condensate completions in each reservoir distributed over a field area of 11,300 acres. Probable final production should exceed 1.3 Tcf of gas and 17.5 MM bbl condensate. Production through 1974 has totaled 530 Bcf of gas an 10.2 MM bbl condensate. The Ellenburger reservoir is the larger producer, accounting for 54 percent of produced gas and 86 percent of produced condensate. Daily average production from the Block 16 field in January 1975 was 348 MMCFG and 5,860 bbl of condensate.

The Devonian reservoir has an average gross thickness of 450 ft (136 m) with an average net pay 83 ft (25 m) thick (> 4 percent porosity). The average porosity within the pay is 6.1 percent. Storage capacity is present in fractured novaculitic chert and in vuggy and intercrystalline dolomite porosity. The Ellenburger reservoir is dolomite with low-grade vuggy and intercrystalline porosity in which the storage capacity has been augmented and rendered permeable by fracturing. Average gross pay in this unit is 800 ft (273 m) thick. Drilled depth to the centroid of the Devonian reservoir is 13,200 ft (4,000 m) with the Ellenburger centroid at 16,400 ft (4,920 m).

APG Search and Discovery Article #90974©1975 AAPG Mid-Continent Section Meeting, Wichita, Kansas