KG-D6, which had hit a peak output of 61.5 mmscmd in March 2010, is currently producing less than 34 mmscmd from Dhirubhai-1 and 3 (D1&D3) gas fields and MA oilfield.
The output from the fields this fiscal would average 28 mmscmd, Reddy said in a written reply to a question in the Rajya Sabha.
A larger than anticipated drop in reservoir pressure coupled with water and sand ingress in well led to D1&D3 gas fields output declining since the second half of 2010.
Reddy said KG-D6 gas production in 2013-14 is projected to drop to 24 mmscmd.
RIL is the operator of the deepsea KG-DWN-98/3 or KG-D6 block with 60 per cent interest while BP plc of UK holds 30 per cent stake. Niko Resources of Canada has the remaining 10 per cent stake.
The Mukesh Ambani-run firm had started gas production from KG-D6 in April 2009 with an output of 30 mmscmd. This hit a peak of 61.5 mmscmd a year later but has since then been declining.
"As the domestic gas availability is projected to decline in the next two to three years, the additional demand will have to be primarily met through imported liquefied natural gas (LNG)," he said.
India's demand for natural gas is projected to rise to 254.2 mmscmd in the current fiscal from 166 mmscmd in 2011-12. It is further estimated to increase to 284.27 mmscmd in 2013-14 and to 356.16 mmscmd in 2014-15.
"The domestic availability of natural gas during June 2011 was around 120 mmscmd while imported LNG comprised 46 mmscmd, totalling 166 mmscmd of domestic consumption," he said.
Reddy said state-owned Oil and Natural Gas Corp (ONGC) would produce 55 mmscmd of gas in the current financial year and in 2013-14. Its output is projected to rise to 58 mmscmd in 2014-15.
Oil India Ltd (OIL) would produce between 8-10 mmscmd of gas during this period while other fields would contribute 13-24 mmscmd.
Total availability of natural gas from domestic sources in 2012-13 would be 104 mmscmd, which would inch up to 105 mmscmd in the following year. It would rise to 133 mmscmd in 2014-15, he added.
Reddy said the gas produced by RIL and ONGC is sold at $4.2 per million British thermal unit while the same from Niko Resources-operated block CB-ONN-2000/2 in Gujarat is sold at $7.03 per mmBtu.