The Lusk Strawn field is about 30 miles northeast of Carlsbad, N. Mex., on a northwest-trending anticline with more than 650 feet of structural relief. The productive unit, in the Middle Pennsylvanian Strawn Group, is primarily a biostrome at approximately 11,300 feet in depth. The productive rock also includes two local bioherms. The pay unit is vuggy, has intercrystalline porosity, and is extremely fractured. The fractures have been important in the creation of porosity and permeability. To August 1, 1966 the field had produced 12,449,426 bbl of oil and 31,585,786 Mcf of gas from 61 wells draining about 10,400 surface acres. Because Lusk was developed on 160-acre spacing, allowables are high and payout is rapid. The discovery of this field has stimulated deep drilling in the region.