GEOLOGY AND PETROLEUM POTENTIAL OF THE KHORAT PLATEAU BASIN IN THE VIENTIANE AREA OF LAO PDR

The Vientiane area of southern-central Lao Peoples' Democratic Republi c (Laos) includes an extension of the Khorat Plateau Basin, which cove rs most of neighbouring NE Thailand. This basin contains one producing gasfield and several other-gas discoveries. The Vientiane area is in the initial stages of petroleum exploration, and no drilling has yet o ccurred. With the aid of new seismic data, the structure and stratigra phy, of the Vientiane area are described in relation to the region's t ectonic history. Some aspects of this history are still poorly underst ood. We suggest that the age of the regional base-Khorat unconformity is Late Jurassic instead of Late Triassic as most previous studies hav e assumed. Recent studies have also shown that the structural inversio n of the Khorat Group began in the mid-Cretaceous and not in the Terti ary. With reference to published information from petroleum exploratio n in NE Thailand, new data from Laos are interpreted as showing that t he Vientiane area has encouraging petroleum potential. Exploration ris k, which is associated with the presence and reservoir qualify of the Permian carbonates which form the primary target, is judged to be lowe st in traps containing Permian palaeo-highs.