Unconventional Shale and Tight Reservoirs of Argentina. Opportunities and Challenges

Resources of 800 TCF and 27 BBO estimated for unconventional shale reservoirs together with more than 50 TCF of gas associated with tight rocks have generated great expectation in Argentina. Actually, the country is very active in developing this type of reservoirs. The formations are located in six main hydrocarbon-producing basins covering a surface of approximately 545,000 km2known as Paleozoic, Cretaceous, Cuyana, Neuquén, Golfo San Jorge and Austral. The associated source rocks are eleven, all of them with potential to be unconventional shale reservoirs. Five are marine in origin while the others were deposited in lacustrine environments. Ages range from Late Devonian to Early Cretaceous. Average TOC are in between 0.5 to 11 (wt%) with variable thicknesses up to 2,000 meters. Vertical wells targeting these objectives range in depths from 2,000 to 5,000 meters. In the particular case of Vaca Muerta Formation, a world class example and the most important unconventional shale reservoir currently being developed, horizontal wells can reach up to 2,000 m long with 20 fracture stages at a cost that varies from U$D 20 MM to 10 U$D MM. More than 650 wells drilled during the last 5 years are currently producing 50,000 bbls/d. Regarding tight clastic and carbonate reservoirs, there are at least eight formations, being the most important in the Neuquén basin. Average vertical wells have 12 fracture stages and cost U$D 9 MM. Tight gas reservoirs represent 20% of the total gas production of the country. Different scenarios consider that unconventional reservoirs could cover 50% of the country hydrocarbon´s demand in 15 years. The current stage of the projects suggests a promising future considering the favourable geological, engineering, political, environmental and social conditions. Consequently, the most important challenge focuses in optimizing operations, services and logistics with substantial cost reductions through time.