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Vada Devonian Field--A Tatum Basin Devonian Oil Discovery

JOHNSON, RONALDO, Texian Exploration, Midland, TX

The 1 Wolverine/Union Pacific Resources State 26 well potentialed flowing 3918 BOPD in March 1988. The well was completed in the Silurian-Devonian dolomite with perforations from 12,646 to 12,678 ft. The discovery well for the Vada Devonian field is in Sec. 26, T10S, R33E in Lea County, New Mexico.

The field is in the northwestern part of the Tatum basin, which is a small regional basin located on the more regionally extensive Northwest shelf of the greater Permian basin. The basin gets its name from the town of Tatum, New Mexico, which is near the center of the basin.

The producing interval for the Vada Devonian field is a dolomite, which is locally cherty and has a maximum thickness of about 1000 ft. The top of the Silurian-Devonian was strongly eroded before deposition of the overlying Woodford Shale, which acts as a source rock and reservoir seal. The Silurian-Devonian overlies the Montoya Formation, a carbonate rock of similar lithologic characteristics.

Basin formation began with the subsidence in the Early Pennsylvanian with maximum development during the Middle Pennsylvanian. The basin ceased to be active in the Wolfcampian because of depositional filling.

The structure consists of folded strata incorporated in fault blocks bounded by nearly vertical fault planes. Oil traps are formed by these north-south-trending faults that are downthrown to the basin. The fault bounding the east side of the Vada Devonian field has approximately 600 ft of vertical displacement.

Most Silurian-Devonian fields in this area have a range of 4-6% primary porosity but due to fracturing, dissolution porosity, and a strong water drive, the Silurian-Devonian is the most prolific structural pay zone in the Tatum basin. Most of the adjacent Silurian-Devonian oil fields average nearly 1 million bbl of oil per well on a 40-ac spacing.

 

AAPG Search and Discovery Article #91011©1991 AAPG Southwest Section Meeting, Abilene, Texas, February 9-12, 1991 (2009)