The Messla oil field is the most recent addition to the imposing list of 20 giant fields which have been discovered within the prolific Sirte basin of Libya. The field, discovered in 1971, is located 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 essential trapping mechanism is the updip truncation of the Lower Cretaceous Sarir Sandstone on a broad structural flexure.

The average oil column of approximately 100 ft (30 m) is productive from an average depth of 8,800 ft (2,640 m) over a 200-sq-km area.

The Messla field is a seismically defined stratigraphic accumulation located on the east-dipping flank of an ancestral basement high. The productive unit is the Lower Cretaceous fluvial Sarir Sandstone which wedges out westward on the Precambrian basement and is truncated by a marked unconformity at the base of the capping Upper Cretaceous marine shales, which are considered to be the source rocks.

The reservoirs consist of two Sarir sandstones separated by a continuous shale bed. Porosity values average 16% and the permeability 450 md. Production as of early 1978 is in excess of 100,000 bbl/day of 40° API gravity oil with a cumulative production of 45 million bbl.

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