land application of drill cuttings and...
TRANSCRIPT
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
21
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
22
• 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
0
5000
10000
15000
20000
25000
0 20 40 60 80 100 120 140 160 180
Soil
TPH
(m
g/kg
)
Time (days)
OBM alone
y = 4780.6e-0.021x R² = 0.8049
0
2000
4000
6000
8000
10000
12000
14000
0 20 40 60 80 100 120 140 160 180
Soil
TPH
(m
g/kg
)
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
c
bc
abc abc
abc
ab abc
abc abc
bc
abc
a a
0
200
400
600
800
1000
1200
1400
1600
1800
Tota
l Fo
rage
Yie
ld (
kg/h
a)
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