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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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Safety aspects of Underground Storage
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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Safety aspects of Underground Storage
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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Safety aspects of Underground Storage
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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Safety aspects of Underground Storage
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