The JDA is geologically located in the North Malay Basin in the offshore lower part of the Gulf of Thailand. The North Malay Basin is a Neogene intracratonic rift/sag basin, elongated in shape, oriented in the northwest-southeast direction and consists of provinces of margin platform, margin ramps and central basinal area or depocentre. Geochemical studies indicate a rich source potential for gas and also for substantial amount of oil. Hydrocarbons within the Malay Basin are found in all of the above provinces. Generally, the North Malay Basin contains thick sediments in excess of 8 km deposited since the Oligocene. Tecto-stratigraphically, the basin is divisible into a Pre-, Syn-, and Post-rift Megasequence. The Megasequence is further divisible into Upper and Lower Post-Rift Megasequence and in some cases in the north divisible into Regional Sagging Megasequence.