ABSTRACT

The San Miguel section of the middle Taylor in the Maverick Basin of the Rio Grande Embayment is a series of overlapping sand bars striking northeast-southwest. Grain size plots and core descriptions indicate that these bars developed in a shallow marine shelf environment. There are as many as five cycles of sand sedimentation, all but one having production established. These sands have a cumulative production of over 50,000,000 bbls. of oil since 1948. Over 30,000,000 bbls. of oil have been produced from stratigraphic type fields discovered since 1970. Stratigraphic type fields have produced over 90% of the total production. Structural traps, caused by differential compaction over volcanic necks, account for the remainder. Torch Field, associated with a volcanic neck in Zavala County, and Sacatosa Field, a stratigraphic trap in Maverick County, are typical fields. The depth and density of control, as well as the subtle expression of the traps, leave many prospective areas.