The Messla oil field is the most recent addition to the list of 20 giant fields discovered within the prolific Sirte basin of Libya. The field, discovered in 1971, lies in the southeastern part of the Sirte basin approximately 40 km north of the supergiant Sarir oil field. Although in an early stage of development the field is estimated to contain approximately 3 billion bbl of original oil-in-place.

The field is a seismically defined stratigraphic accumulation located on the east dipping flank of a broad Precambrian basement high. The reservoir is in the Lower Cretaceous fluvial Sarir Sandstone, which wedges out westward on the basement and is truncated by a basin-wide unconformity at the base of the capping Upper Cretaceous marine shales (considered to be the source rocks). The reservoir consists of two sandstones separated by a continuous shale bed. Porosity values average 17% and the permeability 500 md.

The oil column averages approximately 90 ft (27 m) and is productive from an average depth of 8,800 ft (2,682 m) over 200 sq km. Early 1978 production is in excess of 100,000 b/d of 40° API oil with a cumulative production of 45 million bbl.