Extrapolating Successful Myanmar Irrawaddy Delta Multi TCF Gas Plays into the Deep Water Andaman Sea Basin

Scaife, Gary; Spoors, Richard; Penn, Lauren
Spectrum Geo Ltd, Woking, SURREY, United Kingdom.

The offshore, gas prone Irrawaddy Delta area is considered to be moderately mature in terms of hydrocarbon exploration, while in contrast, to the south, the Indian part of the Andaman Sea Basin remains totally frontier.

The region has evolved through a complex tectonic history that began in the Cretaceous, with the oblique convergence between the Indian and west Burmese tectonic plates. To the south of the Irrawaddy Delta the main tectonic elements that can be observed from west to east include; The Andaman Trench/Inner Slope, Outer High/Trench slope break, Fore-Arc Basin, Volcanic Arc, Back-Arc Basin and the Mergui Terrace. The complex geological history, active tectonics and ultra deep waters have been challenging for explorationists evaluating the region.

A prolific gas prone hydrocarbon system was proven within the offshore Irrawaddy in the Gulf of Martaban with the discovery of world class producing fields of Yandana and Yetagun and a number of smaller sub-commercial discoveries and wells with hydrocarbon indications. This contrasts to exploration in the southern Indian Andaman Sea Basin where exploration has been limited to a small number of (largely unsuccessful) wells located in relatively shallow water near to the Andaman Islands. However the first well drilled (AN-01-1) discovered gas in carbonate reservoirs which are possibly analogous to Yadana in the North, thus proving an active, working petroleum system in the offshore Andaman area.

Analogues from other major deltas, such as the Nile, Bengal and Mississippi, suggest that it is plausible that high quality reservoir sediment input from the Irrawaddy River system can be found within the deepwater Indian part of the Andaman Sea Basin. Although none of the Andaman exploration wells have penetrated significant sandstone sequences, the authors suggest that none of these nearshore exploration wells have targeted structures where Irrawaddy derived sandstone sequences would be found (ie in the deeper water axial parts of both the forearc and backarc areas). The current ONGC drilling campaign is thought to be drilling in these more favourable locations in the forearc basin.

Spectrum currently holds a number of datasets in the region and examples from these datasets will be discussed in a regional geological context and used to extrapolate known plays in Myanmar into the frontier deepwater Andaman Sea Basin in the south.

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