ONGC wants help for G-4 and GS-29 in KG basin

Vol 8, PW 4 (19 May 04) Exploration & Production

ONGC has invited Expressions of Interest from global companies for development of its G-4 and GS-29 discoveries in the Krishna Godavari basin offshore eastern India.

This follows ONGCs reassessment of G-4 prospectivity after its drillship Sagar Vijay drilled a second well, G-4-2, to a target depth of 2,672 metres. According to ONGC, the initial in place estimates for gas at G-4 is 0.77 trillion cubic feet while that for oil in GS-29 is about 53m tonnes.

ONGC will organise a bidders conference on 29th June in Mumbai followed by the sale of bid documents for anyone interested in a Lump Sum Turnkey contract to develop the fields. A dataroom in Mumbai is also planned.

The contract will cover the entire work from concept to commissioning and start of production of hydrocarbons. The contracts scope of work includes: assessment and review of all existing exploration data from GS-29 and the G-4-2 well, preparation of geological models for different hydrocarbon bearing reservoirs, and preparation of oil and gas production scenarios using model based simulation.

G-4 is a deepwater location while GS-29 is in shallow water with prospects of both oil and gas, ONGC tells us. In 1983, ONGC drilled well G-4-1 well but plugged it after concluding there was nothing to show.

But in February 2003, results from fresh 3D seismic and advanced interpretation software data revealed it might have been wrong. This time we identified five high amplitude events within the Pliocene in the form of geo-bodies in the G-4 area, the official said.

In G-4-2 (drilled by Sagar Vijay) these bodies were directionally targeted to test prospectivity. According to ONGC, the well G-4-1 revealed a structurally higher level of geo-bodies and holds more promise than originally thought.

ONGC reveals that amplitude extracts indicate a broad north-west to south-east channel complex extending from GS-29 structure to G-4. The fault zone separating G-4 and GS-29 corroborates the established presence of oil and gas in the horizons close to the channel complex of GS-29 area.

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