Unocal tells ONGC to improve آ“quality of dataآ” for precision drilling

Vol 3, PW 25 (19 Jan 00) Exploration & Production

Elsewhere in Tripura, ONGC is beginning to act on the recommendations of what it describes as a not very detailed report submitted by Unocal on hydrocarbon structures in the state.

The report was commissioned in 1998 to reinterpret old data collected by ONGC's exploration unit from the early 1970s. In its report, Unocal tells ONGC its data is useless and could not facilitate precision drilling, a point acknowledged in private by senior ONGC officials contacted in Tripura by this report.

Much of the data available with us was collected through outdated geological mapping techniques, admits a source. Unocal further advises ONGC to undertake extensive 2D seismic surveys on nine specific structures in Tripura.

It identifies the Konaban structure near Agartala on the Bangladesh border as a deep prospect and recommends drilling upto 4,500 metres. The report asks ONGC to adopt a cautious attitude on three prospective structure in north-eastern Tripura bordering Mizoram state: Khubal, Bachia and Harharganj.

The report says these are small compact structures, but have been exposed for too long to bear much hydrocarbon potential. In a surprising admission, ONGC tells Petrowatch it is unable to undertake extensive seismic surveys in the areas recommended by Unocal because of lack of resources and because it is not in a position to provide security to seismic parties.

Instead, ONGC organised a bidders conference in August last year to meet companies capable of undertaking extensive seismic surveys. A tender has subsequently been floated for seismic surveys over nine structures.

Western Geophysical is among a group of four companies to submit bids. The scope of the work for the tender was finalised in consultation with Dr Allan Stone, a recognised specialist in such surveys.

Stone is currently engaged by ONGC to do 3D surveys in Kashmir.