Geochemistry, palynology, and regional geology of worldclass Upper Devonian source rocks in the Madre de Dios basin, Bolivia

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · AAPG Bulletin

OSTI ID:421170

Peters, K E; Conrad, K T; Carpenter, D G; Wagner, J B ^[1]

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1. Mobil, Dallas, TX (United States); and others

Recent exploration drilling indicates the existence of world-class source rock in the Madre de Dios basin, Bolivia. In the Pando-1 X and -2X wells, over 200 m of poorly bioturbated, organic-rich (TOC = 3-16 wt.%) prodelta to shelf mudstones in the Frasnian-Famennian Tomachi Formation contain oil-prone organic matter (hydrogen index = 400-600 mg HC/g TOC). Our calculated source prolificity indices for this interval in these wells (SPI = 15-18 tons of hydrocarbons per square meter of source rock) exceed that for the Upper Jurassic in Central Saudi Arabia. The Tomachi interval is lithologically equivalent to the Colpacucho Formation in the northern Altiplano, the Iquiri Formation in the Cordillera Oriental, and is coeval with other excellent source rocks in North America, Africa, and Eurasia. All of these rocks were deposited under conditions favorable for accumulation of organic matter, including a global highstand and high productivity. However, the Madre de Dios basin was situated at high latitude during the Late Devonian and some of the deposits are interpreted to be of glacial origin, indicating conditions not generally associated with organic-rich deposition. A biomarker and palynological study of Upper Devonian rocks in the Pando-1X well suggests deposition under conditions similar to certain modern fjords. High productivity resulted in preservation of abundant organic matter in the bottom sediments despite a cold, toxic water column. Low-sulfur crude oil produced from the Pando-1X well is geochemically similar to, but more mature than, extracts from associated organic-rich Tomachi samples, and was generated from deeper equivalents of these rocks.

• OSTI ID: 421170
• Report Number(s): CONF-9609255--
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 8 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
BOLIVIA
EXPLORATION
GEOCHEMISTRY
PALYNOLOGY
PETROLEUM
RESERVOIR ROCK
SEDIMENTARY BASINS
SOURCE ROCKS