• PAGE ONE
• INDEX
• HOME

$250 m underground gas storage station planned in Cambay

Vinod Mathew,

GANDHINAGAR, Jan. 18

THERE is a proposal to convert partially depleted gas fields of the Cambay Basin, some 60 km off Vadodara, into a mega underground gas storage (UGS) station. The three billion cubic metre gas fields, discovered by the Oil and Natural Gas Corporation (ONG C) in 1958, are said to be depleted by 50-60 per cent, and would require the fresh infusion of 1.5 billion cubic metres of gas to become technically viable.

On the cards is the infusion of around $250 million over the next four years to convert the partially depleted fields to an UGS along the lines of some 400 such man-made reservoirs in the US and Canada. One such UGS project that recently got converted fr om a natural gas field was the Husted field near Pittsburg which had fabricated a storage capacity of 3.2 billion cubic feet, with a daily output capacity of 200 million cubic feet.

The blueprint for the mega project in the Cambay Basin is being prepared by Gaz de France (GDF) for the Gujarat State Petroleum Corporation (GSPC). It has shortlisted two gas reservoirs - Oligocene Sand (OS) 2 and 3 in the Cambay fields. The two reservoi rs, together measuring 70 sq km out of the total 160 sq km area of the Cambay Basin, are located at a depth of 1,700 metres.

``All the existing 62 wells would have to be sealed to ensure that there is no leak from either top or bottom as the UGS would need to have 150 atmospheric pressure. On the other hand as many as 50-65 new wells would have to be drilled, some for taking i n the piped gas and the others for taking it out as per commercial demand. A compression facility of 25 MW would have to installed at the site to ensure smooth injection of gas into the UGS station,'' a senior State Government official told Business Line .

The pre-feasibility report for the Cambay UGS was submitted by GDF last October while an advanced report was received on December 5. The next step for the GSPC would be to surrender the Cambay gas fields to the Ministry of Petroleum and Natural Gas as d one in the case of the 5 sq km Mathar oil fields in south Gujarat. Following this, the Cambay fields would then be returned to the State Government which would thereafter give the nod for the Cambay UGS project.

As per the advanced pre-feasibility report submitted by GDF, the Cambay gas fields have a natural advantage as they would not require any cushion gas to be injected as the Gas Initially In Place (GIIP) is advantageously balanced for such a venture, thus saving significantly on capital costs. The cost of cushion gas works out at $4 per thousand cubic feet.

While the cost of the underground gas storage infrastructure would be around $120 million, that of the total projected cost, depending on the quantum of gas that would be handled would range from $215 million to $250 million. The reservoir with 58 wells drilled by the ONGC and another four by the GSPC would see a major portion of the investment going in the re-cementation of the aged walls and bad casing which have been neglected over the past four decades.

Some geo-scientists working with the State Government said the brief to GDF was that the nature of the gas to be stored was LNG with the approximate split coming as methane (95 per cent), ethane (three per cent) and propane and other heavier gases compri sing the remaining portion. The time schedule for getting the project off the ground is 2005, though full capacity realisation it would take another two years.

The two front runners for setting up LNG installations in the State - Shell at Hazira and Petronet at Dahej - were poised to come up with a combined output of approximately 10 million cmd. The Cambay UGS, with a similar mark-up, would provide immense syn ergy to the gas grid that the State Government has undertaken with Gujarat State Petronet Ltd (GSPL) as the single nodal agency for transmission of gas.