--> ABSTRACT: Hydrocarbon Habitat of San Martin and Cashiriari Gas/Condensate Discoveries, Southern Ucayali Basin of Peru, by H. P. Mohler; #91022 (1989)

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Hydrocarbon Habitat of San Martin and Cashiriari Gas/Condensate Discoveries, Southern Ucayali Basin of Peru

H. P. Mohler

Fifteen trillion ft3 of wet gas in place containing some 800 million bbl of associated liquids have been discovered in the San Martin and Cashiriari anticlines, which are located in the Subandean thrusted foldbelt of the Southern Ucayali basin of Peru. Ultimate recoverable volumes are estimated at 10 trillion ft3 of gas and 500 million bbl of liquids including condensate (C5 +) and LPG (C3/C4). Most of these potentially recoverable reserves are located in the Cashiriari structure (80% of the gas and 70% of the liquids). They were encountered in fair-excellent sandstone reservoirs of Early Permian and Late Cretaceous age and are thought to be derived from Carboniferous "coaly shale" source rocks.

The Paleozoic (pre-Andean) sedimentary megacycle is represented by deeper shallow marine clastics of Ordovician to Early Carboniferous age (5,000 m maximum), including Silurian glaciomarine deposits, overlain by up to 1,200 m of Permian-Carboniferous platform carbonates and 600-1,000(?) m of Lower Permian-lower Upper Permian coastal-continental clastics. The Mesozoic-Tertiary (Andean) megacycle is represented by a Campanian-Maastrichtian transgressive marine clastic/carbonate and overlying regressive clastic sequence (450 m maximum), followed by several thousand meters of Molasse-type continental infill of the Tertiary foredeep, which was created by the crustal loading in the wake of the compressional Andean orogeny (Peru, Inca, and Quechua phases).

Late Tertiary folding and thrusting of the sub-Andean belt was superseded by regional Pleistocene uplift, and parts of the foreland continue to subside.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.