PETROLEUM GEOLOGICAL CHARACTERISTICS AND EXPLORATION POTENTIALS OF THE CHACO BASIN, BOLIVIA

The Chaco Basin is one of the Sub-Andean foreland basins with large gas discovery. Based on the historical cases and current exploration status, through comprehensive analysis of drilling and geochemical data, the petroleum geological factors and exploration potentials of the basin are evaluated. There are two main source rocks in the basin, i.e. the Los monos Formation and the Kirusillas Formation, both of which have entered the maturity windows in Carboniferous and Triassic, and the high maturity gas window in Neogene. Gas generated from the two source rocks charged into underlying reservoirs in the Huamampamba Formtion and Santa rosa Formation. Only a little of gas has moved into the overlying reservoirs. Anticlines, thrust anticlines and faulted anticline are often found as traps. Two zones are recommended as exploration targets after careful evaluation, i.e. the western Sub-Andean thrust fold belt and the foothill belt where deeper reservoirs such as those in the Huamampamba Formation and Santa rosa Formation are observed.