Imported LNG

Govt mulls converting Sangu gas field into underground storage

Mir Mostafizur Rahaman | Published: September 07, 2018 09:38:46 | Updated: September 08, 2018 13:24:40

Courtesy: Jiri Rezac

The government is considering a plan to convert the offshore Sangu gas field into an underground storage to store the imported LNG.

Storing natural gas in sub-surface geological formation is commonly known as underground storage.

Under this process, natural gas is stored underground in geological structures whose properties allow gas to be stored and withdrawn when required.

Sangu offshore platform has remained unused since the Sangu gas field was shut down around three years back.

Sangu, the first offshore gas field in the country, was run by Australian oil and gas exploration company Santos.

But it was shut down permanently on October 01, 2013 when its reserves ran out.

The facilities in Sangu include the platform in the Bay of Bengal, sub-sea pipeline and onshore gas processing plant. The onshore gas processing plant is at Fouzdarhat in Chittagong. A 50 kilometre-long 20-inch diameter seabed pipeline is in between the offshore platform and the onshore plant.

Talking to the FE, Abul Mansur Md Faizullah, chairman of Petrobangla, the state-owned energy company, said if they can implement this plan it will help us ensue energy security.

"We are going to conduct a feasibility study first then we shall finalise the next course of action," he added.

People familiar with the development said US energy giant ExoonMobil has shown interest to work on the project, which will be undertaken by Petrobangla.

When asked, Mr Faizullah said that ExoonMobil had shown interest to work with the Petrobangla, but it has not taken any decision yet.

Recently, a government team led by energy adviser Dr Tawfiq-E-Elahi Chowdhury visited some underground storage facilities in Houston of Texas, USA.

The Sangu gas field is suitable as it has the required 'cushion gas,' which allows the storage to work efficiently, ensuring sufficient energy for required delivery.

Cushion gas is the volume of immobilised gas permanently present in the underground storage and cannot be withdrawn.

In many countries in the world, underground storage is used to balance a variable demand with a constant and steady supply, quicker delivery, to handle supply interruptions and to take advantage of expected price changes.

"Underground provision has a number of advantages compared with the traditional LNG terminal. This system is less expensive, there is no need for land acquisition and civil construction," Petrobangla chairman said, defending the plan.

"This can be operated with fewer manpower and supply interruptions are less likely compared with LNG terminals," he added.

The feasibility study will be conducted through geological and engineering studies keeping a view that such reservoirs must be analysed to confirm viability.

Once confirmed, Petrobangla may invite an eligible international energy company to prepare a proposal for the development of the reservoir for the storage in the shortest possible time.

Sangu offshore gas field is connected to the national grid in Silimpur point through a 50 km long pipeline.

According to a primary study, Sangu has the capacity to store 487.91 billion cubic feet of gas.

Sangu has all the features to be an ideal underground as its existing platform will be used as wellhead platform.

But an energy expert thinks otherwise.

Dr Badrul Imam of Dhaka University said there is no justification to take up such a plan.

"We have already huge gas deficit. So I don't see any justification for taking up such a plan," he said.

The feasibility study will focus on several factors including how much gas can be injected and how much can be withdrawn, whether existing wells can be used and how many compressors will be needed; suitability of existing pipeline.

The first underground storage began in Ontario, Canada in 1915, followed by the USA in 1916 and the major development around the world started from 1970s onward.

Presently, over 672 such facilities are in operation around the world, which have the capacity to store 2,424 billion cubic metre of natural gas-or 12 per cent of total world consumption.



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