American Oil and Gas Reporter - February 2020 - 79

Pavillion Gas Is Natural, Wyoming Says
CHEYENNE, WY.-Hydraulic fracturing has no impacts on water-supply wells
in the Pavillion, Wy., area, the Wyoming
Department of Environmental Quality says
in the report concluding a year-long investigation. In Final Pavillion, Wyoming,
Gas Field Domestic Water Wells Report
on Recommendations for Further Investigations, DEQ says any pollution in local
wells likely is naturally occurring.
The state investigation began after the
U.S. Environmental Protection Agency
undertook area samplings from 2009 to
2011 and published a report in December
2011 blaming fracturing for groundwater
contamination allegedly found in watersupply wells in the Pavillion area. It cited
as evidence instances of sporadic bonding
outside production casing directly above
intervals of hydraulic fracturing. The
agency also concluded that gas found in
monitoring and production wells was of
similar thermogenic origins.
The U.S. Geological Survey conducted
its own groundwater study four months
later. Its findings contradicted those generated by EPA, criticized the agency's
testing procedures and suggested faulty
construction of EPA's monitoring wells
might have introduced bias into its samples
(AOGR, December 2016, pg. 20).
Wyoming DEQ also conducted its
own investigation into the rural area east
of Pavillion. According to the state agency,
it developed a planning document for the
water quality investigations in 2013 in
conjunction with EPA and Encana Oil
and Gas USA Inc., and worked on well
integrity and pit investigations conducted
by the Wyoming Oil and Gas Conservation
Commission. In 2014, the agencies collected water quality and operational data
from 13 water supply wells used for domestic consumption, irrigation and stock
tanks, to identify conditions that might
cause palatability or toxicity issues,
Wyoming DEQ says.
"The Petroleum Association of Wyoming
is pleased to have this issue settled once
and for all," says PAW President Pete
Obermueller. "After six years of intensive
investigations by both state and federal
agencies-including the analysis of nearly
14,000 water samples, DEQ has determined
that oil and natural gas development was
not the cause of water issues in the Pavillion
area, but rather naturally occurring phenomena tied to the geology of the area."
Key to the agency's conclusions was
that fracturing fluids were not the cause
of impacts to water wells, and that the
methane found in several domestic wells

was the result of naturally occurring upward
gas seepage, Obermueller adds.
The agencies also studied the integrity
of nearby wells and the Pavillion Gas
Field's history with surface pits. The November 2016 Wyoming Area Domestic
Water Wells Final Report and Palatability
Study issued 10 recommendations for
further investigations; the 2019 final study
focused on two of them:
· Collect additional samples for constituents associated with palatability issues,
including organosulfides and other geochemical/biomarkers for iron and sulfur
bacteria. The additional sampling will
help identify the origin of specific bacteria
and assist in designing treatment methods
for well water.
· Achieve lower method detection
limits for five specific chemicals: 1,2-dibromo-3-chloropropane; 1,2 dibromoethane; acrylamide; hexachlorobenzene;
and pentachlorophenol.
The final recommendation in the 2016
report called on EPA to plug and abandon
the two monitoring wells it drilled in
2010 because of their potential hazard to
groundwater supplies. According to the
2019 report, at the time of its publication
EPA still was working on a plan to close
those wells.
Gas Migration
The 2016 report says the evidence
Wyoming DEQ gathered doesn't indicate
that fracturing fluids used in the Pavillion
Gas Field could have risen to the shallow
depths used by water supply wells. Sustained
bradenhead pressure in several local gas
wells provide indications that gas and possible liquid migration may be happening,
but the agency asserts there is no evidence
any migration has impaired water quality.
Gas found in the field's Upper Wind
River Formation appears to have originated
mainly with upward migration from deeper
commercial gas-bearing zones, and, DEQ
surmises, the upward gas seepage was
happening naturally before gas well development began.
Some wells are experiencing slow gas
seepage, the report says, noting the relative
contributions of potential gas seepage along
gas wells versus natural upward migration
is undefined and difficult to quantify. It
adds the general chemical characteristics
(major cations and anions) of the groundwater from the surveyed wells are consistent
with those reported for the Wind River
Formation across the Wind River Basin.
Declining well yields may play a part
in geochemical changes associated with
the biodegradation of dissolved organic

compounds by bacteria, the report says.
According to the 2019 investigation,
only two organic compounds (an
organochlorine pesticide and a phthalate
ester) were identified at concentrations
exceeding applicable drinking water standards in the water samples. The Wyoming
DEQ points out phthalate is used in flexible
PVC plastics and is a common laboratory
contaminant. Organic constituents at concentrations less than drinking water standards may have originated from agricultural
chemical application and other industrial
uses, or oil and gas activities or spills, it
describes.
Inorganic compounds that were found
generally are associated with naturally
occurring salts, metals and radionuclides,
with many linked to industrial applications,
it says.
"Geochemical changes associated with
the biodegradation of dissolved organic
compounds likely have produced constituents associated with poor water palatability, and appear to be linked to declining
well yields," the 2019 analysis states.
"Limited base line water quality data,
predating development of the Pavillion
Gas Field, hinders reaching firm conclusions on causes and effects of reported
water quality changes."
PAW's Obermueller says the DEQ report confirms what the industry has known
all along: oil and gas development can be
accomplished in an environmentally safe
manner. "Given DEQ's conclusions, PAW
members will continue to operate as they
have for years-with safety and sustainability at the forefront of all they do," he
assures.
r

Henry Hill Continues Work
On N.D. Disposal Project
WILLISTON, N.D.-Henry Hill Oil
Services has completed another 10 miles
of saltwater disposal pipelines connecting
several gathering systems in North Dakota's McKenzie County.
"With the record production experienced
by McKenzie County this year, the need
for saltwater transportation and disposal
has greatly increased," says Matt Lowe,
Henry Hill's chief executive officer.
The company adds that aside from the
10 miles of pipeline constructed in 2019,
ongoing pipeline systems are expected to
continue to 2023. Henry Hill says its saltwater disposal solutions are designed with
unique features, including its Class II disposal wells and gathering systems managed
with SCADA software.
❒
FEBRUARY 2020 79

American Oil and Gas Reporter - February 2020

Table of Contents for the Digital Edition of American Oil and Gas Reporter - February 2020