Potential Shale Plays in Sub-Andean Basins of Peru
The proven resources of shale plays in Argentina (Tithonian-Berriasian Vaca Muerta Fm.), positive early exploratory assessments in Bolivia, Brazil, Colombia and Venezuela, and evidence of gas shows in shales of Ucayali Basin (Devonian Cabanillas Fm.) increase the exploration chances in the Sub-Andean Basins of Peru. Based on geological and geochemical keys this study discusses Peru's potential for shale plays exploration. Madre de Dios Basin is characterized by the presence of three organic-rich shales. Devonian Cabanillas shales (TOC: 1.6–3.8 wt%; kerogen types II/III and III; Ro: 0.64–3.8%; thickness: 100–600 m.), Permian Shinai shales (TOC: 2.5–5.6 wt%; kerogen types II and II/III; thickness: 70–100 m.) and Carboniferous Ambo shales (TOC: 2.3–25 wt%; Ro: 0.4 – 0.76%; kerogen type III; thickness: 100–200 m.). Marañon Basin is characterized by the presence of five organic-rich shales. Cabanillas shales in the SE part of the basin (TOC: 0.79–4.70 wt%; kerogen types II and III; Ro: 1.11–1.35%; thickness: 185–430 m.), Carboniferous Tarma shales in the southern basin (TOC: 1.05–1.65 wt%; kerogen type II/III; Ro: 1.1–1.45%; thickness: 18–254 m.) and Triassic-Jurassic Aramachay shales (TOC: 2–14 wt%; kerogen type II; Ro: 0.67–0.89%; thickness: 350–600 m). Cretaceous Chonta shales (TOC: 0.98–6.00 wt%; kerogen types II and II/III; Ro: 0.45–0.95%) have variable thickness and Oligocene Pozo shales (TOC: 0.5–3.5 wt%; kerogen types I and II) have a widespread areal distribution and variable thickness (50–200 m.). Ucayali Basin is characterized by the presence of five organic-rich shales. Ordovician Contaya shales (TOC: 0.46–2.65 wt%; kerogen type II/III?; Ro: 0.78–3.7%), Cabanillas shales (TOC: 0.65–2.34 wt%; kerogen types II and II/III; Ro: 0.84–2.18%; thickness: 200–1000 m.), Shinai shales (TOC: 1.5–4.0 wt%; kerogen types I/II, II and II/III; Ro: 0.56–1.05%; thickness: 70–100 m.), and Aramachay shales (TOC: 0.53–2.96 wt%; original kerogen was type II, Ro: 0.58–1.40%; thickness: 50–150 m.). Finally Ambo shales (TOC: 0.6–9.0 wt%; kerogen types II/III and III; Ro: 0.77–1.96%; thickness: 25–515m.), have widespread and patchy areal distribution in southern and northern basin respectively. These preliminary results suggest very favourable shale gas potential for three shale units within Madre de Dios Basin and also for five shale units within Ucayali Basin; and in the other hand indicate favourable shale oil/gas potential for five shale units within Marañon Basin.
AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015