The Hull-Silk oil field covers approximately 5,500 acres in north-central Archer County, Texas. Shallow Cisco sands were developed in 1916. Four newly discovered deep reservoirs are being developed. The Cisco and Canyon are described briefly. The Strawn section is described in detail, with emphasis placed upon the lateral lithologic changes.

The structure is essentially a plunging nose with minor closure on the lower beds. Regional folding was greatest in post-Ellenburger pre-Smithwick time. Local folding was greatest in post-Lampasas pre-middle Strawn. An important tilting movement occurred much later.

Oil accumulation is governed by a combination of structure and changing porosity. Prorated allowable in May, 1941, was 15,455 barrels per day. Past production to January 1, 1941, was 3,228,464 barrels. Production for the field is estimated at 40 million barrels. There is no bottom water, and edge water is not encroaching rapidly enough to act as an effective water-drive.