The Lopez field was discovered, June 27, 1935, by the Mills Bennett Production Company, on a block assembled by G. G. Mortimer. The extreme outlines of the pool cover approximately 5,450 acres, the oil-producing area approximates 3,500 acres. Production is from the Lopez or West Cole sand member, which is the topmost member of the Mirando (Eocene) sand series in the pool and is found from 2,045 to 2,311 feet in depth, dependent on the surface elevation and position on structure. The structure consists of a slightly synclinal monocline with the sand lensing out updip and along strike at each end of the field forming a reentrant in the strand line and furnishing the necessary closure for the reservoir. The discovery is attributed to subsurface geology. The oil is typical Mi ando crude ranging in gravity from about 20° to 22° with an average gravity probably slightly in excess of 21°. The field to July 1, 1940, had produced approximately 9,265,000 barrels of oil and was probably about half depleted.