New Delhi: Oil and Natural Gas Corp. Ltd (ONGC) is likely to see output from its largest gas field in Mumbai offshore fall to half by 2012 as natural decline sets in the 20-year-old field.
Gas production from Bassein and its satellite fields will dip to 5,040 million standard cubic meters (about 13.8 million standard cubic meters per day) in 2011-12 from 10,129 million standard cubic meters (27.5 mmscmd) in 2007-08, company official said.
As a result of natural phenomenon, reservoir pressure at the gas field has declined with continuous production for over 20 years, they said.
Bassein field was discovered in 1977, some 80 km west of Mumbai and when in 1988 it began gas production, recoverable reserves were estimated at 226 billion cubic meters (7.98 trillion cubic feet). The reserves are now estimated at about 58 billion cubic meters (2.04 tcf).
Bassein field accounts for 45% of ONGC’s gas production.
Gas output from the field during current year is estimated at 27.3 mmscmd which will fall to 22.75 mmscmd in 2009-10 and to 17.7 mmscmd in 2010-11.
Officials said gas production from Mumbai High will decline from 5,328 million standard cubic meters (14.59 mmscmd) in 2007-08 to 3,188 million standard cubic meters (8.7 mmscmd) in 2011-12 while the same from Neelam, Heera and B-173 fields would dip from 2.7 mmscmd to 2.06 mmscmd.
ONGC hopes to make up some of the decline by putting into operation new and marginal fields that are to begin producing one mmscmd gas in current year, rising up to 13 mmscmd in 2011-12.
ONGC’s total gas production from offshore fields in 2007-08 was 16,457 million standard cubic meters (45 mmscmd) which is estimated to decline to 39.1 mmscmd in 2011-12.
Gas production from onland fields will, however, increase to 21 mmscmd in 2011-12 from 16 mmscmd, officials said.
The company produced 22,334 million standard cubic meters (61.18 mmscmd) gas in 2007-08. This will marginally fall to 22,003 million standard cubic meters (60.2 mmscmd) in 2011-12.