Paleolatitude and Hydrogeology Controls on Lacustrine Source Rock Quality: A Comparative Study from Northeastern Asian and South American Basins

Andrus, Vlad; Xu, Tianguang
IHS, Houston, TX.

Northeastern Asian and South American basins contain a vast portion of the world's petroleum reserves that originated from lacustrine source rocks. Lacustrine oils in China and Brazil amount to more than 90% of their total reserves. This study compares the differences and similarities of lacustrine source rocks deposited in diverse paleolatitudes as well as in contrast hydrological conditions (freshwater vs. saline lakes). Considered lacustrine source rocks from NE and SW quarterspheres are distinguished mainly with regards to their depositional settings, TOC contents, kerogen types and compositions of generated hydrocarbons. Special attention is also paid to the organic matter production and preservation. Such a complex approach helps to establish relationships of lakes' paleogeography, hydrology, organic matter production and preservation with source rocks quality and reserves produced.

Comparative analysis of lacustrine source rocks deposited in different settings demonstrates that most prolific lacustrine source rocks from South American basins were deposited under more arid conditions than those from Northeastern Asia (mostly tropical-subtropical). In Latin America, most productive lacustrine source rocks were deposited in the Lower Cretaceous brackish-saline lakes of contemporary Brazil. Those in present China were deposited in the Cretaceous freshwater lakes and Tertiary freshwater to hypersaline lakes.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012