Chapter 21: Petroleum Source Rock Analysis in the Western Caribbean Region: An Overview

Abstract Compilation, analysis, integration, and interpretation of geochemical data from oil and gas fields, exploratory and scientific wells, oil and gas seeps, and outcrop samples allows the identification of effective and potential Cretaceous and Tertiary source rocks throughout the western Caribbean. In this vast region, seven source rocks of different ages are proven to be considered source rocks: (1) lower–middle Eocene Punta Gorda and Touche Formations along the Nicaraguan Rise (SR1), (2) middle Eocene, Yellow Limestone Group in Jamaica Island (SR2), (3) late Cretaceous (Cenomanian–Campanian) Loma Chumico Formation present mainly in northwestern Costa Rica (SR3), (4) middle Miocene Gatun Formation in Panama and Costa Rica (SR4), (5) late Cretaceous (Coniacian–Campanian) Cansona Formation in the Sinu and San Jacinto basins (SR5), (6) Oligocene to early Miocene Cienaga de Oro and lower Porquero Formations and age-equivalent units in the Lower Magdalena Valley basins (SR6), and (7) late Cretaceous (Coniacian–Santonian) rocks in the Colombian and Venezuelan basins (SR7). Although the Cretaceous section sequence is generally considered the most likely source rock in the northern part of the South American plate, data from the Venezuela and Colombian basins suggest that the petroleum generative potential of the Campanian–Maastrichtian rocks is a non-source rock, normally with total organic carbon values < 0.5%. Also, in the Mosquitia Basin offshore Honduras and Jamaica Island, the middle and upper Cretaceous contain low organic matter, suggesting the absence of source rock. The identification of several source rocks in the western Caribbean region is quite encouraging; however, future geologic research and petroleum exploration will allow to constrain the geographic distribution of the source rocks already identified and to refine in more detail their geochemical characteristics and petroleum generative potential.