natural gas storage

8/10/2019 natural gas storage

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NATURAL GAS STORAGE


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STORAGE

Natural gas uses in a year fluctuates.

Space heating in homes and other buildings

consume large amounts of gas. This is

seasonal fluctuation in the total gas demand

from summer to winter.

Other reasons for gas demand fluctuations

will be


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Typical natural gas load curve


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Main storage possibilities of natural

gas

Generally, gas storage methods arecategorized into two parts: surface andunderground.

Underground Gas Storage (UGS) consists ofdepleted oil & gas reservoir storage, Aquiferstorage and salt cavern storage.

Surface storage consists of Liquefied NaturalGas (LNG), Compressed Natural Gas (CNG)storage, Natural Gas Hydrate (NGH) storage,


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Main storage possibilities of natural

gas

Gas To Liquid (GTL) storage, and pipeline

capacity storage.

Among the above methods, LNG and depleted

reservoir are commonly used for gas storage

in high capacity. NGH is also a new technique

that has been suggested for high capacity gas

storage.


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Underground Gas Storage

The whole process is comprised of injecting natural

gas into the subsurface reservoir during periodsthat demand falls below the gas supply. Whendemands exceed the supply, the gas will be

withdrawn from a reservoir The most important characteristics of an

underground storage reservoir are

Its capacity to hold natural gas for future use,

High deliverability rate,

Being nearest to the consumption centers,


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Existence of structure overlain by a caprock toaccumulate gas in the storage zone,

Sufficient depth to allow the storage to takeplace under pressure,

No existence of fault,

A porous and permeable rock beneath thecaprock that permits gas to be stored and flow

readily,Water below the storage zone to confine the

stored gas


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Aquifer storage For storage in aquifers, the gas storage

capability of the aquifer must initially beconfirmed by drilling and testing wells. In an

aquifer, the pressure needs to be higher thanthe original pressure in order to be able toinject any gas. These types of UGS are usedwhen there are no Depleted Reservoirs. Thesereservoirs account for only 10-15% of the totalUGS.


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Aquifer storage


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Underground Gas StorageSalt cavern storage

The development of storage caverns in salt forgas storage has been a popular alternative tosurface storage.

Important factors for design considerationinclude cavern shape, cavern depth, in-situtemperatures, and gas pressure cycle

The Salt Cavern provides very high withdrawaland injection rates. Cavern construction is costly,but the ability to perform several withdrawal andinjection cycles each year reduces the cost of thisproject.


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Underground Gas StorageDepleted oil & gas reservoir storage

The most common type and best method of UGS is thestorage of gas in depleted oil and gas reservoirsbecause of their wide availability.

The first step in performing this project is the

conversion of production reservoirs to storagereservoirs.

Due to the capability of caprock, known geologicalproperties of reservoir, and the existence of porous

and permeable rock, wells, surface facilities, andpipeline systems, investment costs are reduced, andtherefore performing the project is simpler than othertypes of UGS.


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Underground Gas StorageDepleted oil & gas reservoir storage

For further benefits, re-injecting gas is associatedwith an increase in pressure within the reservoir,which can also lead to a period of increased oil

recovery. These reservoirs currently provide 70%of the gas storage volume

The storage facility consists of components suchas: Underground reservoirs, wells, gathering

system, compressor, central point metering,central point separator, central point dehydrator,transmission Line


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Storage in pipelines

Pipelines are used as temporary natural gasstorage in short period of time when demand islow.

By intermediate natural gas compression stationsenable pressure in the main pipeline to be raisedwith corresponding rise in the amount of gasstore in pipes.

When gas demand increases, stores gas can besupplied to utilities by lowering the pressure inpipeline system


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LNG storage

Liquefied natural gas or LNG is a natural gas(predominantly methane, CH4) that has beenconverted temporarily to liquid form for easeof storage or transport. It is an odorless,

colorless, non-toxic, non-corrosive natural gaswhich has been liquefied at pressures close toatmospheric pressure by cooling it toapproximately -162C (-260F).

Liquefied natural gas takes up about 1/600ththe volume of natural gas in the gaseous state


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LNG storage

A typical LNG chain


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NGH storage

The formation of natural gas hydrates is a well-known problem in the petroleum and natural gasindustries, but nowadays with significant

development of technology NGH can be used as amethod of natural gas storage.

In this method of gas storage, there is no need forhigh pressures or very low temperatures. For

NGH storage at atmospheric pressure, thehydrates should be stored at a subzerotemperature near equilibrium


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NGH storage

Schematic NGH Production Process

natural gas storage

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