Loma La Lata Giant-Gas Field of Neuquen Basin, Argentina: Field Characterization

Alfredo Gorgas, Guillermo A. Jalfin, Nidia Rios

Loma La Lata Field is a giant-gas and condensate field discovered in 1977 in the East-Central sector of Neuquen Basin with original reserves of 8.3 TCF of gas and 0.2 BBL of condensate. Neuquen Basin is a back-arc triangular shaped basin with the longest north-south axis in the West. Sequence architecture of facies associations which include siliciclastic carbonate and evaporites suggest that the basin fill was dominated by complex relationships between custacy, subsidence and sediment supply rates. The gas discovery has been completed in the lower section of Tordillo Formation (Kimmeridgian) known as Sierras Blancas Formation in the Neuquen Embayment area. The basal succession consists of fluvial-eolian to playa lake facies deposited as lowstand systems tracts immediatel above the 144 M.y. sequence boundary. The lowermost braided fluvial red member does not have good enough reservoir quality to yield gas or condensate at commercial rates, but has 273 ft of net gas pay sand in the upper eolian green member. The gas column at Loma La Lata is 1335 ft with a proved area over 94,000 acres. All evidence indicates that the gas bearing sandstone is a unique, continuous and non faulted reservoir. The gas accumulation is stratigraphically trapped due to both diagenetic processes and facies changes. Although diagenetic trapping among the eolian deposits appears to be related to the sandstones composition rather than to facies type, the directional permeability seems to be driven by internal stratifications.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995