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Summary Letter from COGCC on Sampling Efforts
Conducted Fall, 2008
Note: this report was edited for uninterrupted content flow - removing
unnecessary headers and footers Names were also removed.
Re: Alleged Gas Seep Investigation
COGCC #200191771 and #200200082
Garfield County, Colorado
Date: December 31, 2008
[added]
The Colorado Oil and Gas
Conservation Commission (COGCC) has investigated the various issues and
concerns you have submitted to the COGCC dating to June 2008. The issues,
concerns and complaints raised, the investigative actions taken and results
of analytical testing are summarized in this letter.
The main issue appears to
be a concern that petroleum hydrocarbons and or other materials
related to oil and gas
operations have impacted your property and that an active methane gas seep
is occurring. This concern is based on your review of engineering reports,
observations made of gas bubbles in the West Divide Creek and other surface
water features including beaver ponds and other areas of standing water,
white precipitate material observed on the ground surface, black material
that seeps from creek banks, various odors, the appearance of orange and
purple films/sheens on surface water features and areas of stressed
vegetation.
To investigate these issues
multiple members of the COGCC environmental staff made a total of four site
visits to your property from June 2008 to December 2008 to collect samples
from assorted media including plant, soil, surface water, a ground water
seep and a permitted water well for laboratory analysis. A summary of the
field investigations including a discussion of the analytical data is
provided below.
June 30.2008
COGCC environmental staff
visited the site and collected three surface water samples for analysis of
benzene, toluene, ethyl benzene, and total xylenes (BTEX) and biological
activity reactive tests (BART). The surface water features sampled included
West Divide Creek and two areas of standing water. Additionally, one sample
of the black "seep" material was collected and analyzed for diesel range
organics (DRO). The analysis was conducted by TestAmerica, Inc. (TA) in
Arvada, Colorado. The analytical data report for the June 30,2008 sampling
is included as Attachment 1.
Water
No BTEX compounds were
detected in the three water samples.
The BART analysis was
conducted onsite and tested the water for Iron-Related Bacteria (IRB),
Sulfate-Reducing'Bacteria (SRB) and slime forming bacteria (SLYME). The test
results indicate a high activity level of IRB and SRB bacteria. Iron-related
bacteria are oxidizing agents that use iron and or manganese to generate
brown slime and can produce unpleasant odors and can be corrosive. IRB are
also known to generate strong smells that can resemble fuel odors and can
generate yellow, orange and red-colored water. Sulfate-reducing bacteria
live in oxygendeficient environments and break down sulfur compounds
producing hydrogen sulfide which smells like rotten eggs.
A pamphlet prepared by the
Colorado Department of Public Health and Environment that describes the
affects and issues that IRB and SRB bacteria can generate is included as
Attachment 2.
Soil (Black Seep Material)
Diesel range organics were
detected at a concentration of 9.9 milligrams per kilogram (mg/kg) in the
"black seep" material which is slightly above the reporting limit of 5.6
mg/kg. Review of the gas chromatograph indicates that this detection is not
indicative of a diesel fuel or a biodiesel material. Diesel would show a
hump or bell-shaped curve (usually with many sharp spikes) on the
Chromatogram, centered on the "Diesel Range Organics" flag. The pattern for
Bio-diesel would show several large peaks in the kerosene boiling range.
September 25. 2008
On September 25,2008 COGCC
environmental staff visited your property and spent approximately four hours
walking the site, taking notes and photographs of the areas of concern and
collecting analytical samples. Soil and water samples were submitted for
environmental analysis. The environmental samples were submitted to
TestAmerica in Arvada, Colorado. The laboratory reports are included as
Attachment 3. Two sand samples were collected and submitted for analysis
using x-ray diffraction (XRD) and optical microscopy.
Water Sample
One surface water sample
was collected from an area of standing water (Area 2) on the east side of
the West Divide Creek. Your concern or issue was that it was not normal for
water to pond or collect in this area. The sample was analyzed for volatile
organic compounds (VOG), semi-volatile organic compounds (SVOC), dissolved
methane, total metals, anions and general water chemistry. The water was
relatively clear, colorless and had no odor. No VOC or SVOG were detected.
The vac and svac results are summarized in Tables 1 and 2, respectively.
Dissolved methane was detected at 43 micrograms per liter (ug/l), or
parts per billion, as noted in Table 3.
3. General water chemistry
parameters indicate the water quality is relatively good (Table 4).
The total dissolved solids
concentration was 520 milligrams per liter (mg/L) and the pH 7.6. No
nitrates or nitrites were detected. The chloride concentration was 7.1 mg/L.
The calcium concentration was 77,000 ug/L, which is 77 mg/L, sodium 53,000
ug/L (53 mg/I), magnesium 41,000 ug/L (41 mg/L), barium 190 ug/L (0.190
mg/L), iron 610 ug/L (0.61 mg/L), and bicarbonate 440 mg/L. An
additional sample of the water from Area 2 was collected on October 14, 2008
and submitted for analysis of dissolved metals. Concentrations were: calcium
88,000 ug/L (88 mg/L); sodium 64,000 ug/L (64 mg/L), magnesium 50,000 ug/L
(50 mg/l) and barium at 0.190 mg/L. The inorganic results from both sampling
events are summarized in Table 4 and the laboratory reports are included in
Attachment 3.
Soil Samples
Seven soil samples were
collected from areas throughout the property. A brief summary of the samples
collected, issues for each area and the analytical parameters tested is
provided below.
Additionally, a sample of
frac sand was obtained from EnCana Oil & Gas USA Inc. (EnCana) and
submitted with the two soil samples for optical microscopy and XRD. Please
note that the frac sample was labeled as Area 15 and not as trac sand to
ensure that the laboratory was not biased before analytical work was
conducted.
SEPTEMBER 25, 2008
SOIL SAMPLING SUMMARY
Sample Issue/Concern
Analysis
Location
Area 1 Landowner concerned
frac sand has been intruded into BTEX GRO/ORO SAR, pH, Optical microscopy,
subsurface and onto surface causing distressed Sc, XRO vegetation.
Area 3 Orange biofilm,
dark/black to gray soils, with decay odor BTEX GRO/ORO landowner concerned
that gas or oil seep is occurring.
Area 4 Orange biofilm,
black soils, with decay odor, also near BTEX GRO/ORO area where fluid seeped
from creek bank: landowner concerned that gas or oil seep is occurring.
Area 5 Landowner had
previously observed black material GRO/ORO bubbling up.
Area 5 Sandy area on creek
bank between areas 4 and 5. Optical microscopy Concerned about stressed
vegetation and that more sand analysis, XRD was present than in past.
Concerned that frac sand had been intruded into area.
Area 8 Black soil. GAO/ORO
Area 9 Orange and
purple biofilm. GAO/ORO
Area 10 Stressed vegetation
and white/orange precipitate materi. SAR, pH, Sc, total metals.
"Area 15" Frac sand sample
obtained from EnCana for comparisor Optical microscopy analysis, XRD
No BTEX or GRO compounds
were detected in the soil samples. ORO were detected in the Area 4 sample at
a concentration of 6.4 milligrams per kilogram (mg/kg) with a reporting
limit of 5.4 mg/kg and in the Area 8 sample at a concentration of 8.1 mg/kg
(Table 5) with a reporting limit of 4.8 mg/kg. TestAmerica was contacted to
determine if naphthalene, a common component of diesel fuel had been tested
during the ORO analysis and if so to provide reports summarizing the
results. These results were received on December 5, 2008. Naphthalene was
not detected in either sample. Reviews of the gas chromatographs indicate
that these detections are not indicative of a diesel fuel. Diesel would show
a hump or bell-shaped curve (usually with many sharp spikes) on the
chromatogram, centered on the "Diesel Range Organics" flag. The pattern for
bio-diesel would show several large peaks in the kerosene boiling range.
A sample of the white and
orange precipitate material observed on the surface was collected in Area 10
for chemical analysis. Results indicate the material contains calcium at
13,000 mg/kg, magnesium at 3,800 mg/kg, iron at 11,000 mg/kg, potassium at
2,400 mg/kg and sodium at 12,000 mg/kg. The sodium adsorption ratio was
1,800 and the pH 11 as summarized on Table 6. These results indicate that
the material is an evaporative deposit. Sodium, calcium, and magnesium were
also detected in the standing water sampled in Area 2, see Table 4 for
reference. It is not uncommon for salts of this type to be deposited on the
ground surface as standing water evaporates and or infiltrates into the
subsurface. There are no indications that this material is related to an oil
and gas activity.
Sand
The comparison of the sand
samples from Areas 1 and 5 to frac sand was conducted by OCM Science
Laboratory, Inc. (OCMS) in Wheat Ridge, Colorado. The Area 5 sample was
described by OCMS as: consisting primarily of quartz with lesser amounts
of feldspar, mica and trace minerals. Grain size varied from 10 um to
approximately 500 um. The morphology is angular to sub-round. Quartz
grains resembling frac sand were not identified.
The Area 1 sample was
described as: being similar to Area 5 but with a finer grain size.
It is composed primarily of quartz with lesser amounts of feldspar, mica,
carbonate, and some hematite and possibly trace amounts of clay. Grain size
ranged from 10 um to 250 um and grain morphology in angular to sub-rounded.
The "Area 15" sample was described as: representing frac sand with
quartz being the sole component. The grains range from 600 um to 1. 1
um and exhibit a high degree of roundness and sphericity. Grains
of this type were not identified in the previous two sand samples. The OCMS
report is included as Attachment 4.
October
14, 2008
Water
A sample was collected from
the Eicher-Bracken water well on October 14, 2008. Samples were submitted to
TestAmerica for analysis of dissolved methane, BTEX, GRO/ORO, SVOCs, metals
(total and dissolved) and general water chemistry. No BTEX, GRO, ORO or SVOC
compounds were detected (Table 7). The inorganic water chemistry was similar
to water quality from the Area 2 sample (see Tables 8 and 9). The water
contained sodium at a concentration of 78,000 ug/L (78 mg/L), calcium at
77,000 ug/L (77 mg/L), magnesium at 3,800 ug/L (3.8 mg/L) and bicarbonate
470 mg/L.
Soil
A soil sample was collected
by the Creek Filter House (CFH). The sample was submitted for BTEX, GRO and
DRO analysis. No BTEX or GRO compounds were detected. DRO at a concentration
of 12 mg/kg were detected (Table 10). The laboratory reports for samples
collected on October 14, 2008 are included as Attachment 5. Review of the
gas chromatograph indicates that this detection is not indicative of a
diesel fuel or a biodiesel material. Diesel would show a hump or bell-shaped
curve (usually with many sharp spikes) on the chromatogram, centered on the
"Diesel Range Organics" flag and the pattern for bio-diesel would show
several large peaks in the kerosene boiling range.
Plants
A sample of grass near the
Creek Filter House (CFH) and leaves from a stand of oak trees were collected
on October 14, 2008. The stressed grass was black, very dry and corresponded
to an area of black to dark brown soil located near the CFH. The oak trees
appeared to be distressed with dry brown leaves with black spots/patches.
The samples were submitted
to the Colorado State University Plant Laboratory for analysis. The report
from the CSU observed that the oak trees were exhibiting natural senescence.
According to the plant laboratory the grass appeared to have been dead for
sometime and that it had been colonized with fungi. The report is included
as Attachment 6. No impacts from oil and gas activities were detected.
December 4, 2008
Water
Sampling and Site Visit
On December 4, 2008 COGCC
Acting Director [name retracted], COGCC [name retracted] EPS and COGCC
Engineer [name retracted] met with you and staff from Cordilleran Compliance
and EnCana on site to discuss the historic sampling of the Eicher-Bracken
water well and the two monitoring wells (MW23, and MW27) located on your
property. A report that provided historical laboratory data, maps and
responses to questions about past sampling reports was discussed.
COGCC staff collected a
sample of water seeping out of a terrace deposit immediately above the creek
bank. The sample was submitted for inorganic analysis, total and dissolved
metals, BTEX, DRO/GRO and dissolved methane to Evergreen Analytical, Inc. in
Wheat Ridge, Colorado on December 5, 2008.
BTEX, GRO-DRO and dissolved
methane were not detected (Table 11). Inorganic analysis as summarized in
Table 12 indicates that the water is similar to the water in the Eicher-Bracken
water well which accesses shallow groundwater and surface water. Laboratory
data reports are included as Attachment 7.
Grass and Hayfields
On December 3, 2008 you
sent an email indicating concern that pasture land near the Schwartz well
pads exhibited signs of distressed vegetation related to a methane gas
seep(s). Photographs of stressed fields and other fields as a comparison
were provided. On December 4, 2008 during the onsite meeting you provided
additional photographs and a map of the area of concern. Follow-up emails
and telephone calls have been made. This complaint is being addressed under
COGCC complaint #200200082.
On December 4, 2008 [COGCCC
names retracted] toured the area in question and made observations of the
various fields. There are noticeable differences with the various fields.
However, the differences appear to be based on land use and agricultural
practices. One field is an irrigated. cultivated hay-field while the areas
of concern are un-improved pasture or rangeland that do not appear to be
irrigated and in some cases appear to have been used for cattle grazing.
There are no indications of an ongoing methane gas seep. The Garfield County
Extension Office has been contacted and the Extension Agent Patrick McCarty
has agreed to review these issues. Photographs and maps have been submitted
for his review and if necessary COGCC environmental staff will meet with him
to review the condition of these fields.
Engineering Review
COGCC staff researched the
drilling and completion records of all wells drilled to date from the
Schwartz (EnCana designation 02) and the Juniper (EnCana designation M1 E)
well pads. Since the original problem in the Divide Creek area was caused by
a high bradenhead pressure acting against surface casing set at a shallow
depth in the Schwartz 2-158 wellbore, we reviewed bradenhead pressures and
surface casing setting depths for the area in detail. We also reviewed our
records for any gas kicks that were reported during the drilling phase of
these wells.
Our review of casing design
in this area shows all surface casing (excluding the Schwartz 215B) to be
set at a depth greater than 1000 feet. Four of the wells on the Juniper well
pad have casing set deeper than 1500 feet and three of the wells in the area
also have intermediate casing set below 2800 feet. These deeper casing
strings insure that gas produced from the Williams Fork formation remains in
the well bore and will not escape into shallower zones.
EnCana also monitors
bradenhead pressure (this is the pressure acting against the surface casing
shoe) on a regular basis. The COGCC allows EnCana to vent the bradenhead of
any well showing a pressure increase in weIIbore annulus. By allowing EnCana
to vent this excess pressure, any natural gas entering the annulus cannot
increase to a level of pressure sufficient to bypass the surface casing.
This eliminates the possibility of gas migrating from the well bore into
shallower sands. Also, wells that have the bradenheads vented will
eventually show lower bradenhead pressures. EnCana is currently venting the
bradenheads on nine wells in the area and these pressures have decreased
from an average pressure of 216 psi to 74 psi measured when the bradenhead
is not vented.
We find two wells have a
record of gas kicks in the area (excluding the Schwartz 2-15B). The Schwartz
11-2A had surface casing set at 1024 feet and encountered a gas kick at a
depth of 4186 feet. The shut-in casing pressure recorded at the time of the
kick was 500 psi and the kick was immediately killed by increasing the mud
weight from 9.2 to 11 pounds per gallon.
The Juniper 2-16A well had
surface casing set at 1527 feet and had a gas kick occur at 4305 feet. The
shut-in casing pressure recorded at the time of the kick was 325 psi and the
kick was immediately killed by increasing the mud weight from 10.6 to 11.7
pounds per gallon.
Based on this information,
we do not have any reason to believe there is contamination of ground water
due to faulty well bore construction.
GAS SEEP SAMPLING REQUESTS
During the 2008 complaints
you have requested that gas bubbling from surface water features be sampled.
However, the gas has not been sampled for various reasons as outlined below.
1. COGCC staff did not
observe gas bubbling during the September or October site visits. During the
December 2008 only possible traces of bubbles were noted in West Divide
Creek. Most observers' onsite did not observe any gas bubbling.
2. Two groundwater samples
and one surface water sample have been analyzed for dissolved methane
concentrations since June 2008. Only trace levels of dissolved methane have
been detected.
3. A detailed review of
engineering data does not support the theory that a thermogenic methane gas
seep is occurring on your property.
4. Previous Gas Sampling
Events:
In 2004 COGCC staff
collected four gas samples from various surface water features on your
property. The laboratory data, including isotopic analysis, showed that the
gas was of biogenic origin.
In 2007 COGCC staff
collected gas samples from two ponds on your property. The analysis showed
that the methane was of biogenic origin. The laboratory data was provided in
a letter report dated January 10, 2008.
In 2007 EnCana retained a
third party contractor to collect samples of gas bubbling from surface water
features on your property. The gas analysis showed that the methane was
clearly of biogenic origin.
5. West Divide Creek, as it
runs through your property, is surrounded by wetlands and areas of standing
water such as beaver ponds and water retained behind flood debris. The
presence of gas bubbles from wetlands and other stagnant surface water
bodies is a natural phenomena and is not an indication of impact from oil
and gas operations. Methane seepage from wetlands is one of the largest
sources of naturally occurring methane emitted to atmosphere.
6. The Colorado Division of
Wildlife (CDOW) completed biological and chemical sampling of West Divide
Creek on the Bracken and Langegger private properties on July 10, 2008.
Electrofishing was conducted in a 445 foot stream reach (average stream
width of 13.5 feet) that encompassed multiple microhabitats (riffles, runs,
pools). According to CDOW staff multiple age classes of all species were
observed including and three species that displayed spawning colors and/or
spawning tubercles. Macroinvertebrate and water quality samples were also
collected. The presence of the multiple age classes and reproducing species
could be considered positive indicators for the overall health of the
stream. The final report is pending at this time, however, the CDOW has
raised no issues or concerns with COGCC staff.
Summary
In addressing the issues
and concerns you have raised this summer and fall the eOGCC has conducted
four site visits, has collected eight soil, four surface water, two
groundwater and two plant media samples for laboratory analysis. At this
time no indication of a petroleum hydrocarbon impact or ongoing methane seep
related to oil and gas activities has been identified.
No voe, SVOC, or GRO
hydrocarbons were detected in the numerous samples collected. Inorganic
analysis of surface water and ground water are comparable and show no
indications of impact from oil and gas activities.
The DRO detections are not
consistent with a diesel fuel and are more indicative of naturally occurring
hydrocarbon material such as terpenes from pine needles and wood, tannic
acids from leaves, humic acids from decaying grass, roots, and leaves and or
aromatic oils from sage and similar plants.
The sand samples collected
from Areas 1 and 5 are not similar to frac sand. Areas 1 and 5 were
different in composition, texture and grain size from the frac sand ("Area
15" sample).
Biofilms: The orange and
purple films and sheens are naturally occurring biofilm; BART testing shows
that IRB and SRB bacteria exist in the surface water. Laboratory testing
(Tables 4,6,8) indicates that the surface water, ground water and soils
contain iron and also manganese which are used in the oxidizing process by
IRB. A side effect of this process is the generation of brown slime and
orange and red colored water. The presence of these purple and orange films
in a wetland environment is a natural occurrence and is not indicative of an
ongoing or past impact from oil and gas operations. No biofilms were noted
during the December 2008 site visit.
The black "seep" material
appears to be an organic sandy soil generated by the decomposition of plant
materials in wetland environment. No vac, svoe or GRO compounds were
detected and the ORO detections are outside of the pattern that a diesel
fuel would generate.
Odors: One of the issues
cited as an indication that an ongoing gas seep was occurring was the foul
odors described as the odor you get when you light a gas stove. Methane
however is an odorless gas. The odor noticed when a gas distribution system
leaks or a gas stove is being lit is an odorant purposely placed into the
gas prior to retail sale. The odorant used is frequently a mercaptan.
Mercaptans are flammable compounds which are commonly known in the gas
processing industry has stench or skunk gas.
The Colorado Oil and Gas
Conservation Commission staff take all complaints from surface owners and
concerned citizens seriously and welcomes citizen involvement and input.
However, due to overwhelming evidence from the current and past
investigations, the COGCC finds no indication of an ongoing thermogenic
methane seep or other impacts from oil and gas operations and our
investigation in to your complaint is complete at this time.
Respectfully,
[name retracted]
Environmental Protection Supervisor
Colorado Oil and Gas Conservation Commission
Attachments:
1. TestAmerica Laboratory Report 08G020186
2. TestAmerica Laboratory Report 081260319, 081260300
3. COPHE IRB, SRB Pamphlet
4. OCMSL Report
5. TestAmerica Laboratory Reports 08J150119, 08J150140
6. Colorado State University Report
7. Evergreen Analytical, Inc. 08-9307
cc: [names retracted]
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