AAPG Annual Convention and Exhibition

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Generation Potential of the Pamplona Formation – Central Western Peruvian Basin


Growing population and elevated life standards are expected to increase energy demand; therefore, the exploration of new hydrocarbons sources is needed. New hydrocarbon potential in Peru is just emerging. Traditionally, at least 12 sedimentary basins in the Amazon and the northern Peruvian coast are being explored and exploited, but outside these areas almost no wildcatting has taken place in the 6 other basins until recently, due to lack of investment and past socio/political struggles. Thanks to seismic interpretation, prospective pre-Tertiary sediments from late Paleozoic to late Cretaceous were identified, promising unexpected offshore hydrocarbon potential. Blocks in this area have been incorporated in 2013 bidding round for Peruvian offshore exploration. In addition to these offshore resources, researchers agree that it is highly likely the existence of good reservoirs seals and traps in the onshore part of the basin, but currently no explorations are being performed in those areas. Study of hydrocarbon source rock quality and thermal history can contribute key evidence on whether hydrocarbons could have formed and migrated in this onshore part of the basin. During field exploration a new potential source rock have been identified in various localities within the Pamplona formation in the onshore part of the central western Peruvian basin and chronologically placed in the Barremian-Aptian ages corresponding to the Oceanic Anoxic Event OAE-1a. Cretaceous marls with high content of organic matter were identified, clearly recognized by its black to dark brown color and smell. Currently, regional stratigraphic and structural studies are being done. Samples at 3 outcrops (approximately 65 Km far-apart from each other) are being collected in order to determine Total Organic Carbon (TOC) as a first screening of the general potential of hydrocarbons generation. Samples showing TOC greater than 1% will be analyzed by Pyrolysis Rock-Eval (peaks S1, S2, S3, OI and HI parameters will be processed) to evaluate the nature of the organic matter, and the hydrocarbon oil-vs-gas potential. The results of maturity from the pyrolysis analysis will be assessed by the color of palynomorphs and expressed as Thermal Alteration Index (TAI), indicative of paleotemperature, hence, hydrocarbon window indicator. Results of these analyses as well as the hydrocarbon generation potential of the unexplored Pamplona formation will be presented at the conference.