CANNON, ROBERT A.
Consulting Geologist, Dallas, Texas

Abstract: Navigator Field, Dickens County, Texas - A Case of Integration

Navigator (Tannehill "B" Sandstone) Field is 9.5 miles southeast of Spur, Dickens County, Texas, USA, in the northeastern end of the Eastern Shelf of the Midland Basin. This paper describes the integrated exploration processes that discovered the complex stratigraphic reservoir.

The discovery well, Neeley A-1, was drilled based on subsurface geological mapping of the Tannehill "B" Sandstone. Geology was supported and enhanced by soil gas geochemistry and dipmeter (FMS) data from a down-dip show well drilled by the same operator two months earlier. The Neeley A-1 encountered 28 feet (8.5 m) of Tannehill Sandstone at an approximate depth of 4400 feet (1340 m) and potentialed 167 BOPD + 16 BWPD (pumping).

The Tannehill "B" Sandstone is the most pervasive of three sandstone units between the base of the Stockwether Limestone and Croton Creek Limestone. Data from samples, sidewall cores, dipmeters (FMS/FMI), and electric logs indicate Tannehill "B" Sandstone was deposited during a regressive cycle of fluvial-deltaic sedimentation and is encased between two transgressive cycles of limestone deposition. The sandstone represents both fluvial bars and distributary channel bars.

As of September 1998, Eastern Energy drilled 24 producing wells in the field. The field produced more than 1/2 MMBO and is expected to yield 3-4 MMBO after secondary recovery.

A thorough understanding of the geology and relatively inexpensive geochemical techniques found significant reserves compared with other surface exploration techniques employed in the area. The discovery showed how an integrated exploration program, using area-proven tools and ideas, finds reserves cost-effectively. Navigator Field revived interest in the area.

AAPG Search and Discovery Article #90918©1999 AAPG Southwest Section Meeting, Abilene, Texas