Safety Aspects of Underground Storage in Aquifers And

8/6/2019 Safety Aspects of Underground Storage in Aquifers And

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Safety aspects of Underground Storage

in Aquifers and CavernsUnderground storage of Hydrocarbon:

At depths of 1,500 feet or more, the free pore

space of a suitable rock formation can beoften used for storage of natural gas or

compressed air.


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in Aquifers and CavernsThe rock formation layer must be adequately

porous with good permeability and have an

impermeable overburden which will not let

the stored gas escape either vertically or

laterally.

Generally speaking, sandstones, dolomites,

porous limestones or fractured rocks aresuitable for such storage.


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in Aquifers and CavernsStorage space in an aquifer is created by injected

gas under pressure to displace free water.

PB Energy Storage Services developed the only

compressed air energy storage test facility in

an aquifer in Pittsfield, Illinois.


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in Aquifers and Caverns

Depleted oil or gas reservoirs represent a particulartype of porous storage.

PB Energy Storage Services engineers can analyzedepleted oil and gas zones for natural gas storagepotential and design exploratory programs tolocate and qualify aquifers for storage.

PB is experienced in both developing new storagefacilities and enhancing the deliverability ofexisting facilities.


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in Aquifers and Caverns

Underground storage of Hydrocarbon:

Safe, economical and environmentallyfriendly way to store large volumes of

hydrocarbons, energy sources, chemical

products etc.


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Typical products - natural gas, crude oil, fuels,

propane / butane, air, chemical and

petrochemical products

The capability to store products depends on

the existence of suitable geological conditions


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AQUIFERS

Aquifers are the safe and effective way of

storing large volumes of gases in the

subsurface

Products stored in aquifers are Natural gas,

CO2

, crude oil, fuels, propane / butane, air,

chemical and petrochemical products


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AQUIFERS

Because of the different operational modes and

larger storage volume storage aquifers is more

applicable to CO2 sequestration than storage in

salt.

The development of aquifers to store natural gas

requires a number of exploratory studies such as:an appropriate underground structure with

sufficient closure, the quality of the cap rock etc.


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CAVERNS

Caverns are the safe and effective way of

storing large volumes of gases in thesubsurface for short-term storage.

It is because they can quickly switch frominjection to withdrawal and operate at large

injection and extraction rates.


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CAVERNS


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CAVERNS


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CAVERNS


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Dual Entry Salt Cavern

1. Product in/out

2. Brine in/out

3. Product

4. Brine

Schematic cross-section through a typical hydrocarbon storage cavern in the

Sarnia area. This cavern is "dual entry" meaning there are two wells used to

service the cavern. One well (Product in/out) is used for injection of

hydrocarbons into the top of the cavern when filling the cavern. To empty the

hydrocarbons from the cavern, salt water (brine) is injected using the second well

(brine in/out) and the hydrocarbons are displaced to the surface up the first well.


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CAVERNS

Salt caverns in Ontario are located in the Sarniaand Windsor areas at refineries and petro-chemical plants.

The caverns are used to temporarily storehydrocarbons and liquified petrochemicals and are

a critical component of the petrochemical industryin this area.

There are 73 active storage caverns in Ontarioutilizing 124 wells with a total storage capacity of

3.5 million cubic meters. If the caverns were filled to capacity the contents

would have a value in excess of $1.6 billion.


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Salt caverns are man-made features constructed

within thick beds of salt in the subsurface ofOntario.

They are formed by drilling through the overlayingstrata down into the salt formation to the

calculated cavern location, and washing the cavernto the appropriate size.

Salt caverns are formed with a leaching process byinjecting a water stream down a well bore in order

to "wash" a cavern into the salt.

The wall of the completed cavern is insoluble inhydrocarbons and therefore prevents leakages.


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CAVERNS

Two types of Caverns:

1. Hard rock caverns

2. Mined caverns (caverns in salt deposits)


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Risk associated with Cavern/Aquifer

Construction and Operation

Since construction takes place hundreds of feetbelow ground in confined areas, any mishaps,

such as a collapse, can have graveconsequences

The health and safety risks to constructionworkers are burns, falls, overexertion, heatexhaustion, radiation exposure, and exposureto solvents, electrocution, falling debris and

other hazards.


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Improper or worn out tools and equipment can

result in burns to the skin and eyes.

The improper use of or not using respirators

when priming and painting steel surfaces canresult in overexposure to poisonous solvents


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The erection of steel structures with cranes, in the

presence of power lines, may pose an

electrocution risk.

The x-ray equipment contains a radioactive(gamma ray) source, which can result in serious

injury to construction workers if the material is

improperly handled.


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Risks relating to operating the facility may impact

operations personnel as well as the general public.

Gas leaks due to ruptured piping, well leaks,

equipment malfunction, operator error and otherexternal factors.

Spills of hazardous chemicals such as used

lubricating oil and the glycol used for removingwater from the gas


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SAFETY SYSTEMS/FEATURES

RECOMMENDED DURING OPERATIONS Emergency shutdown (ESD) valves

ESD conditions

Fire detection

Leak detectors Manual ESD

Alarms

Wellhead protection

Monitoring storage operations Emergency response plan (ERP)

Employee safety training plan

Testing and maintenance program

Documents

Safety Aspects of Underground Storage in Aquifers And