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In-Depth Information
TABLE 4.4 Comparison of Regulations for Wells in the EPA UIC Program
Class
II
V
VI
Use
Injection of brines and other
luids associated with oil and gas
production and hydrocarbons
for storage. Injected beneath the
lowermost USDWs (150,851 wells). a
All injection wells not included in
Classes I-IV. Generally used to inject
nonhazardous luids into or above
USDWs and typically shallow onsite
disposal systems (estimated 640,000
wells). b Of this number, approximately
234 wells are used for the injection of
luids in association with the recovery
of geothermal energy for heating,
aquaculture, and production of
electric power (EPA, 1999). Permits
for geothermal injection wells can be
issued by the BLM in addition to state
agencies or the EPA. c
Inject carbon dioxide (CO 2 ) for long-
term storage, also known as geologic
sequestration of CO 2 (estimated 6-10 wells
by 2016).
Siting
All new Class II wells shall be sited
in such a fashion that they inject
into a formation which is separated
from any USDW by a conining zone
that is free of known open faults or
fractures within the area of review (a
conining zone is a formation that is
capable of limiting luid movement
above an injection zone) (see 40 CFR
146.22(a)).
Class V wells have no speciic siting
requirements.
Owners or operators of Class VI wells
must demonstrate to the satisfaction of
the Director that the wells will be sited
in areas with a suitable geologic system
(see 40 CFR 146.83(a)). Conining zones
free of transmissive faults or fracture and
of suficient areal extent and integrity
to contain the injected carbon dioxide
stream and displaced formation luids
and allow injection at proposed maximum
pressures and volumes without initiating
or propagating fractures in the conining
zone(s) (see 40 CFR 146.83(a)(2)).
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