Appendix G. Drill cuttings and fluids dispersion modelling ...
Land Application of Drill Cuttings and...
Transcript of Land Application of Drill Cuttings and...
Land Application of Drill Cuttings
and Fluids
Chad J. Penn
Department of Plant and Soil Science
Oklahoma State University
What is “land application”?
• Often used synonymously with the terms
“soil farming” or “land farming”
• Technically, land application is neither of
these
– “soil farming” and “land farming” are
remediation techniques for soils that have
become contaminated
– “land application” is a method of disposal
that aims to prevent contamination of soils
What is drilling mud? • Drilling mud is used for O&G Exploration
• Several uses for the drilling process
– Seal formations
– Remove/ suspend cuttings
– Lubricate and cool the drill bit
– Control corrosion on drill stem
– Control well bore pressure
• Operators adjust their “recipe” for each
hole
• The mud is recycled until it cannot be used
What is drilling mud?
• Some of the many additives may include:
– Bentonite Clay (lubricator/ sealer/ viscosity)
– Barium Sulfate (weight)
– Lime (corrosion)
– Soda Ash (NaCO3 - water conditioner)
– Lignite (viscosity control)
– Loss Circulation Material (sealer)
• ground peanut shells, mica, cellophane, walnut
shells, calcium carbonate, plant fibers, cottonseed
hulls
Types of mud
• Water (WBM) and oil based (OBM)
– WBM uses water as solvent
– OBM uses diesel as solvent
• Have different characteristics for different
purposes in drilling
– Varies between well, region, and operator
• Typically, WBM is used in the vertical portion of
the hole and OBM is used in the curve and
horizontal portions
Contents: WBM
• Typical contents
– Dissolved solids
• Mostly Na, Ba (BAR), Cl
– Minor amounts of Ca and K
– Bentonite (Gel)
• Can add nutrient holding capacity to sandy
soils
– Water (for water portion)
Contents: OBM • Typical contents
– Petroleum hydrocarbons (TPH)
– Dissolved solids
• Not as high as for WBM
– Calcium carbonate equivalent (CCE)
• From natural bedrock, additives, or bulking agent
– Minerals rich in Ca, Mg, and K
• Depends on bedrock at specific location
Risks: WBM
• Salinization of soils
– Excess salts: reduces the ability of the
plant to uptake water.
• Remedy: leach out with natural rainfall and
time
• Sodic soils
– excess Na: poor drainage, poor structure
little growth
• Remedy: gypsum + water
Risks: OBM
• TPH toxicity to plants
– Not a long term risk
• TPH degraded into CO2 and H2O through
soil microorganisms
– Optimize conditions: temp, pH, nutrients,
oxygen
– “Bio-Treatment”
– Salinization and Sodicity
• Not as much of a risk as for WBM
Risks: OBM
• BTEX
– Benzene, toluene, ethyl benzene, and xylene
– Benzene is the most water soluble
• Degradation time varies from 10 to 60 days
– Guardian: 44 mg/kg
– DEQ: 0.03 mg/kg
» Threshold assumes soil filled with benzene from
surface to GW and no degradation
• Metabolized by plants into non-harmful compounds
– Experiment to begin: benzene leaching
Risks
• Radioactivity: not likely, but possible
– NORM (naturally occurring radioactive
material)
• Soils range from 0.2 to 4.2 pCi/g in NORM
• OK threshold for application is 30 pCi/g
– Outreach laboratory, Broken Arrow
($150/sample for NORM)
Risks
• Heavy metals (Cu, Zn, As, Pb, etc.)
– Unlikely; will depend on local geology
– Not from additives, but from naturally
occurring geologic formations (rock)
– Metals do not degrade
Rules and Regulations: OK
Corporation Commission • Max 8% slopes
• At least 12 inches of acceptable soil texture
• Must maintain buffer zones (property boundaries,
perennial streams, ponds, water wells, etc.)
• E.C. Less than 4,000 µS and E.S.P. less than 10% in
receiving soil
• Depth to bedrock, 20 inches for WBM, 40 inches for
OBM (may change to 20 inches)
• No water table within top 6’ of Soil Profile
• WBM may be re-spread after 3 years has passed and
Soil test requirements met
• OBM sites can not be re-used for WBM or OBM
– May change to every 3 years
Permissible Loading
• Use Most Limiting Factor Calculations
from OK Corporation Commission
– Must not exceed loading rates
• 6,000 lbs/ac TDS
• 3,500 lbs/ac Cl-
• 40,000 lbs/ac TPH
• 200,000 lbs/ac Dry Weight (For Solids)
Handling of Mud
• OBM is spread only as a solid
– Incorporated
– Must be mixed with bulking agent at a 3 parts agent to 1 part OBM ratio
Economics
• ~ 50¢ per bbl WBM
• ~ $1.00 per bbl OBM
• Therefore, total cost paid to landowner depends on the well and operator
– Ex. Typical Ellis County well results in $5000 for WBM and $8000 for OBM portion.
• Expect a decrease in yield for a period
– Payout vs. temporary yield decrease: is it worth it?
• Depends on many factors including yield potential
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Keys for Producers
• The more available acres, the better
• Check the reputation of the spreading contractor
– Call OCC and find out if they have had many problems
• Good contractors will work with you from beginning to
end
• Can NOT use CRP ground
• Ask questions
• If problems do arise, by rule, a bona fide effort must be
made to reestablish vegetation
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• Early stages: much work to be done
• OBM spreading / handling methods
– Gypsum vs Ag Lime
– Is the 3:1 ratio needed? Too much?
– Other Amendments?
– Is the ‘Death Penalty’ necessary?
– Rainfall timing and TPH degradation rate
– Impact of TPH load and concentration on
degradation rate
Research
Current OBM Research:Treatments
• 3 bulking agents
– Gypsum, caliche, and lime
• 3 ratios of bulking agent:OBM
– 3:1, 1.5:1, and 0 (mud alone)
• Manure amendment applied to mud alone
and gypsum bulked
– Plant available N rate (PAN) and 1.5 PAN
TPH Degradation
rainfall y = 15228e-0.022x
R² = 0.9689
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Soil
TPH
(m
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)
Time (days)
OBM alone
y = 4780.6e-0.021x R² = 0.8049
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TPH
(m
g/kg
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Time (days)
1.5 Gypsum:OBM + PAN Manure
98% of TPH degraded in 170 days Day 170 TPH ranged from 72 to 430 mg kg-1
Forage Yield
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Treatments
Research
• Impact of salts from WBM
on wheat and grass
– Evaluate application timing
and rate
• Lahoma: wheat and grass
• Assessment tool for
predicting safest site
specific WBM application
or time required for salts to
leach
Lahoma Field Day: May 10th