Rajasthan NELP blocks could hold small gasfields

Vol 8, PW 24 (09 Mar 05) Exploration & Production

Rajasthan is likely to attract some interest following Cairn Energys discoveries last year at RJ-ON-90/1.

NELP-V offers RJ-ONN-2003/1 and RJ-ONN-2003/2 in Rajasthan. Both lie in the Mesozoic (Jaisalmer) Basin to the northwest and west respectively of Cairns block.

But the geology of the Cairn block is totally different, we are told. The Cairn block is in the Tertiary Rift Basin and is a northern extension of the Cambay basin.

Still, expect structural cum fault closures in the middle part of block RJ-ONN-2003/1 at the Permian-2, Cretaceous and Paleocene levels at depths of between 1000 and 3000 metres. No wells have been drilled on this block but it could hold medium-sized gasfields.

This is a medium risk block of possible interest to ONGC or Oil India. In the second Rajasthan block, expect fault closures at the Palaeozoic and Mesozoic levels, in the western portion.

Small accumulations of shallow gas prospects are likely between 300 metres and 1000 metres and deeper prospects at about 2500 metres. In the Cambay Basin two blocks are on offer: CB-ONN-2003/1 Part A &B and CB-ONN-2003/2.

ONGC has already drilled five wells in the first block. Geological data reveals thin reservoir development at the Eocene and Oligo-Miocene sequences leading to expectations of small closure-cum-wedge out prospects at depths of between 1500 and 3000 metres.

Prospectivity is marginal, we learn. Only the eastern half of Part A is worth exploring as it lies in the vicinity of ONGCs Kanawara and Akholjuni fields.

Part B is sandwiched between the small-sized North Kathana and Kathana fields and only the left over areas between the drilled wells are of interest. On the second Cambay block 11 wells have been drilled.

All of them have been abandoned, we learn. You can expect small structural closures and fault prospects at the Hazard level as well as small roll-over sands at the Olpad level.

These two blocks could be of interest to ONGC, GSPC or Niko.