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Prospectivity and Hydrocarbon Potential of the Afghan-Tajik Basin, Central Asia

Jameson, Matt P.¹; Johnson Sabine, Rosemary¹; Ng, Lorraine¹; Jackson, David²; Protacio, John A.²
¹Exploration, Tethys Petroleum Ltd, London, United Kingdom.
²ARKeX, Cambridge, United Kingdom.

Central Asia represents a frontier in hydrocarbon exploration with world-class fields discovered in the Pri-Caspian basin of Kazakhstan and the Amu-Darya basin of Uzbekistan-Turkmenistan-Afghanistan. Further unexplored potential exists in the sub-salt of the Afghan-Tajik basin, which shares a similar Jurassic stratigraphy to the Amu-Darya basin, however few wells have targeted Jurassic sub-salt plays in the Afghan-Tajik basin. The acquisition of state-of-the-art potential fields and seismic data has greatly improved the understanding of this hydrocarbon province, with interpretation unlocking the sub-salt potential of this frontier basin.

The application of regional gravity, magnetic and seismic datasets enabled the characterization of regional structural trends, highs and depocenters. Following on from the regional interpretation, a bespoke high resolution full tensor gravity (FTG) and magnetic survey was flown, in order to better understand the tectonic and sedimentary history of the Afghan-Tajik basin. The data revealed a greater complexity in the pre- and post-salt petroleum systems, exposing a range of new stratigraphic (reefs, ramps, lowstand wedges) and structural plays (imbricate thrust systems, lateral ramps), providing a new perspective on pre-Jurassic basin structure and its relationship to the surrounding area.

The use of analogues to the pre-salt of the Afghan-Tajik basin has been crucial in assessing the exploration risk for pre-salt plays. The Amu-Darya basin remains a favorable and relevant analogue due to its similar structural evolution in the Mesozoic and petroleum system. The key pre-salt play of the Amu-Darya basin is a stratigraphic Upper Jurassic reef play, charged by a Jurassic source rock. These pre-salt plays can be oil-, gas- or condensate-bearing with supergiant potential (e.g. the Yolotan Field, Turkmenistan). For analyzing the post-salt petroleum system, structural analogues to those of the Appalachian and Columbian fold-thrust-belt fields have proved very useful, with recent seismic acquisition revealing a greater complexity in Cretaceous, Palaeogene and Neogene structure than was previously identified.

The conclusion of this study suggests that great potential exists in both the pre- and post-salt petroleum systems of the Afghan-Tajik basin, with state-of-the-art datasets aiding in the interpretation of this complex petroleum province.

 

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