Oil and Gas at Your Door? (2005 Edition) - Earthworks

Oil and Gas Development and Impacts
subsurface, evaporating it in disposal ponds, and releasing it to watercourses such as rivers or
ephemeral streams.
Injection/Reinjection: Approximately 90% of onshore produced water from conventional oil and
gas sites is reinjected into a well for production enhancement, or disposed of by injection into
a disposal well. 300
Reinjection of produced water to enhance the recovery of oil or gas typically involves a closed
system from the producing well bore to the injection well bore, so the potential for spills and soil
contamination is minimized. 301 Production enhancement is discussed in the section on Stages
of Oil and Gas Development.
At a BP-Amoco well southeast of
Durango, Colorado, CBM produced
water was reinjected into an aquifer that,
unbeknownst to the company, connected
to a natural fracture system. The produced
water traveled underground and
forced hot water that had been in deep
aquifers up toward the surface. This
caused a nearly 50 degree Fahrenheit
temperature increase in a hot spring 1½
miles north of Durango. Water output at
the hot spring also increased. The temperature
at the hot springs decreased after
BP-Amoco agreed to inject water into a
different aquifer. Nancy Van Dover, a
local resident, told the Colorado Oil and
Gas Conservation Commission how disposal
wells had caused her well-water
temperature to rise to 100 degrees. The
water also became highly mineralized
and destroyed her sink, toilets and shower.
305
When using disposal wells, produced water is usually required to be injected
into known formations, such as a former producing formation, or aquifers
known to have water quality that is worse than the quality of produced
water. 302 If water is being injected into a formation, the formation must be
capable of receiving the huge volumes of injected water. But subsurface
geology is not always known or predictable, and there may be unintended
consequences from injection of produced water. (See the box on BP-
Amoco's reinjection problems.)
Produced water from CBM operations is not used to enhance methane
recovery. Underground injection is, however, used as a method of disposal
of CBM produced water. 303 Also, if the water is of good enough quality, produced
water may be injected into a formation that will store the water, which
will enable it to be retrieved at a later date.
Storage or Disposal in Evaporation Ponds or Percolation pits: Produced
water may be placed in pits and allowed to either evaporate or percolate into
the surrounding soil. According to the U.S. EPA, this approach is declining
because of potential contamination of groundwater and the potential hazard
posed to birds and waterfowl by residual oil in these open pits. 304
Often, impoundments do not contain water effectively, and leaks are common.
Water may end up in rivers and streams, increasing the salts in these
watercourses. The water also evaporates from the pits, which wastes water
that could otherwise be used to recharge aquifers. 306
Swamping may also be an issue if produced water is held in ponds. Near
Gillette, Wyoming, produced CBM water is often stored in ponds before it is discharged in
drainage systems. In some cases, produced water has seeped from the ponds into near-surface
sediments. Sediments can only absorb so much water, and if additional water cannot be transmitted
fast enough to deeper soils surface swamping will occur. 307
The oil and gas industry often talks about creating a beneficial use for produced water. One of
these supposed beneficial uses is the creation of artificial ponds or reservoirs using produced
water that is non-toxic to wildlife. This may seem like an environmentally sound option for the
water, since the reservoirs can provide wildlife habitat, fish ponds and recreation areas. The
problem is that over time, CBM water production will decline. When this happens, ponds and
reservoirs will dry up, green areas will turn brown, and wildlife and fish that have come to rely
on this source of water will lose their habitat. As one critic puts it: “Creating and then destroying
environs in this callous fashion is an unacceptable impact to the land.” 308
Discharge to Streams: For this disposal method the water is supposed to be treated to meet
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