Located in the northeastern
part of the Indian subcontinent, Upper Assam
basin is the oldest oil producing province in India. The Eastern Himalayas and the Naga-Patkai Hill
Ranges associated with
massive thrust faults respectively marks the
north-western and south-eastern limits of the
The northeastern limit of the basin is marked by Mishmi Hill massif and south-western limit by Mikir Hill
massif. Early exploration was concentrated in the thrust and the fold belts, where numerous oil seepages occur. This led to discovery of Digboi oil field in 1889 within the thrust belt area, in the plunging part of Jaipur anticline, on the overthrust block of Naga thrust. After discovery of prolific oil fields in the Brahmaputra valley, attention of national oil companies was diverted to this foreland (or "shelf") leaving the thrust belt
("Schuppen Belt") under explored.
Block AAP-ON-94/1 covers the area between the Naga thrust and the Singyang thrust. It appears to contain at least two major hydrocarbon trends, the Assam Shelf trend and the Foothills trend. The
Jorajan, Kusijan, Shanti-Tarajan and Digboi oilfields are located along the block boundary, whilst the giant Nahorkatiya oil field is only a short distance away. The abandoned Makum oil field is located within the block. Initial work began in November 2000 resulting in identification of multiple play types based on which the consortium acquired new seismic data in 2003. Several sizeable prospects have now been mapped and the consortium is
Exploring stacked reservoirs in
Girujan,Tipam and Barails. Dirok well drilled
by the consortium has confirmed the
presence of multiple Gas sands in Girujan.
The consortium has announced this
discovery and has plans for further
exploration and appraisal.