DRILLING MUD EVALUATION

AWMA Oil & Gas Environmental Compliance Conference

May 13-14, 2014

Washington, PA
PROJECT 

SUMMARY

• Coal Bed Methane (CBM) 

project in Queensland, 

Australia

• Upstream development 

area consists of two areas 

of ~3,200 mi2

• Pipelines to LNG Plant on 

coast

• Downstream LNG terminal 

for shipment
PROJECT 

SUMMARY

• >14,000 production wells to be 

drilled over ~20 years

• Well depths from ~500 to 2,600 

ft
Wells spaced on 2,600 ft grid, 

resulting in one well per 160 

acres.
Waste Production

• 200 to 250 yd3 of drilling muds and 

cuttings produced per well

• ~40% cuttings~60% liquids. 

• Historically, all cuttings disposed on 

site. 

• Liquids historically trucked to treatment 

facility or left to evaporate
NEW WASTE MANAGEMENT 

REQUIREMENTS

State government requiring 

systematic framework for drilling 

waste management:

• Direct reuse of surplus material

• Reuse following treatment to 

remove impurities (recycling)

• Beneficial use of liquids and 

solids

• Disposal of liquids and solids 

unsuitable for other options

0% 20% 40% 60% 80% 100%

Drilling Mud Recycling

Beneficial Re-use of Water

Beneficial Re-use of Solids 

Burial or Disposal 

DRILLING AND CUTTING VOLUMES (%)

Target drilling muds/cuttings 

management
Study Objective

• Assess potential long-term options for 

effective management of drilling wastes.

Approach

• Assess the potential human health and 

environmental risks associated with 

different management options and 

identify mitigation measures to reduce 

the risks.
SCOPE OF WORK

1. Review physical, chemical and toxicological properties of the 

drilling mud additives;

2. Evaluate chemical analysis from previous drilling pit sampling and 

collect additional soil samples from more recent drilling sites; 

3. Develop conceptual exposure models and complete Persistence, Bioaccumulation, and Toxicity (PBT) analysis;

4. Complete a qualitative screening assessment of concentrations to 

standards;

5. Evaluate potential drilling mud management and beneficial use 

options; and

6. Develop management practices to reduce risks associated with 

long-term management options for drilling muds.
DRILLING MUD COMPOSITION 

• Base fluid (water)

• Weighting agent (e.g barite)

• Viscosifiers to remove cuttings (e.g. bentonite)

• Filtration control (e.g. Lignite)

• Biocide

• Salts (reduce swelling)

• Alkalinity and pH Control Materials

• LCM material
DRILLING MUD 

COMPONENT 

LIST

Material Components Cas Number Percent 

Composition

Aus Plug cross-linked polyacrylamide NA 100

Barite Quartz (silica crystalline) 14808-60-7 <3

Barium sulfate 7727-43-7 >89

Additives NA <6

Biocide G tetrakis(hydroxymethyl)phosphon

ium sulfate

55566-30-8 18-25

Water 7732-18-5 remainder

Caustic Soda sodium hydroxide 1310-73-2 98.4

Silica 7631-86-9 0.003

Citric Acid citric acid 77-92-9 >99

Water NA <1

Fracseal Cellulose NA 100

KCL Water 7732-18-5 35-80

Barite 13462-86-7 <20

calcium carbonate 13397-26-7 1-20

sodium chloride 7647-14-5 1-20

potassium chloride 7447-40-7 2-10

fluid loss additive NA 1-5

magnesium oxide 1309-48-4 <2

Viscoifier NA 0.1-1

Quickseal blend of sized organic fibers and 

fine mineral articles

NA 100

RHEO-Plug polyacrylic polymer NA >95

Salt sodium chloride 7647-14-5 97.5-100

Sodium 

bicarbonate

sodium bicarbonate 497-19-8 >99

Sodium sulphide Sodium sulphide >99
PBT (PERSISTENCE, BIOACCUMULATION, 

AND TOXICITY) EVALUATION

Criterion PBT Criteria

P For PBT purposes a chemical is considered persistent in a particular media if its half-life in the media exceeds the following:

Half-life (T1/2) >2 months in water

Half-life (T1/2) >6 months in soil

Half-life (T1/2) >6 months in sediment

Half-life (T1/2) >2 days in air

B For PBT purposes a chemical is considered to be bioaccumulative if it has a BCF/BAF of >2000, or in its absence of any BCF/BAF measurement a log 

Kow >4.2.

T For PBT purposes, in respect of aquatic toxicity, a chemical may be considered toxic under the following circumstances (corresponding to criteria for 

GHS chronic category 1:

Non-rapidly degradable substances for which there are 

adequate chronic toxicity data available

Chronic NOEC or ECx (for fish) <0.1 mg/L and/or

Chronic NOEC or ECx (for crustacea) <0.1 mg/L and/or

Chronic NOEC or ECx (for algae or other 

aquatic plants)

<0.1 mg/L 

Rapidly degradable substances for which adequate 

chronic toxicity data are available

Chronic NOEC or ECx (for fish) <0.01 mg/L and/or

Chronic NOEC or ECx (for crustacea) <0.01 mg/L and/or

Chronic NOEC or ECx (for algae or other 

aquatic plants)

<0.01 mg/L 

Substances for which adequate chronic toxicity data are 

not available (providing criteria for P and B are met)

96 h LC50 (for fish) <1 mg/L and/or

48 h EC50 (for crustacea) <1 mg/L and/or

72 or 96 ErC50 (for alage or other aquatic 

plants)

<1 mg/L 

And the substance is not rapidly degradable and/or the experimentally determined BCF is 

>500 (or, if absent, the log Kow is >4.2

Toxicity to other (terrestrial) organisms Should be considered on a case by cases basis, compared with the highly toxic 

classifications DEWHA has developed for ag/vet chemicals

Long term toxicity or evidence such as endocrine 

disruption effects

Should be considered on a case-by-case basis.
PBT SUMMARY

Product Hazard Assessment

AUSPLUG Not anticipated to be hazardous to human health/environment

BARITE Not anticipated to be hazardous to human health/environment

BIOCIDE G Liver effects (oral RfD = 0.004 mg/kg/day); very toxic to aquatic 

organisms. 

CAUSTIC SODA Corrosive product but not anticipated to be hazardous human health/environment.

CEMENT CLASS A Product is an irritant, but not anticipated to be hazardous to human health/environment

CITRIC ACID Not anticipated to be hazardous to human health/environment

DEFOAM-A (DG) Not anticipated to be hazardous to human health. Very toxic to aquatic organisms.

DEFOAM-A (NON DG) Not anticipated to be hazardous to human health. Toxic to aquatic life with long-lasting 

effects.

FRACSEAL FINE Not anticipated to be hazardous to human health/environment

FRACSEAL MEDIUM Not anticipated to be hazardous to human health/environment

LIME Product is an irritant, but not anticipated to be hazardous to human health or environment

QUICKSEAL COURSE/FINE/MEDIUM Not anticipated to be hazardous to human health/environment

POTASSIUM CHLORIDE Not anticipated to be hazardous to human health/environment

POTASSIUM SULFATE Not anticipated to be hazardous to human health/environment

POTASSIUM SULFATE POLYMER DRILLING FLUID Not anticipated to be hazardous to human health/environment

RHEOBEN NT Not anticipated to be hazardous to human health/environment

RHEOPLUG Not anticipated to be hazardous to human health/environment

RHEOPAC-LV/RD Not anticipated to be hazardous to human health/environment

SALT Not anticipated to be hazardous to human health/environment

SAPP Not anticipated to be hazardous to human health/environment

SODIUM BICARBONATE Not anticipated to be hazardous to human health/environment

SODIUM SULPHITE Not anticipated to be hazardous to human health/environment

XANTHAN GUM Not anticipated to be hazardous to human health/environment
PBT SUMMARY

• In general, compounds generally not considered to be persistent or bioaccumulative in the environment 

• Although some compounds (eg. Biocides) are toxic or corrosive, when 

they are present in flow back water they will readily degrade or 

dissociate in the environment and will not bio-accumulate in terrestrial or 

aquatic species

• Salts can be mobile and exhibit phytotoxic effects
SAMPLING 

PROGRAM

• Collect samples from 

current operations

• Analyze for metals, 

BTEX, TPH, PAHs

• Evaluate historical and 

current results and 

compare to 

applicable standards.
SCREENING RESULTS

ANALYTE

No. 

Detects Max

95% 

UCL1

Residential 

Vapour

RBSLV

2

No.

> RBSLV

Residential

Direct Contact

RBSLDC2

No.

> RBSLDC

COPC3

(95% UCL

> RBSL)

Antimony 4/78 48 - - - 31 1/78 N

Chromium 78/78 220 38 - - 100 3/78 N

Lead 76/78 333 37 - - 300 1/78 N

Benzene 27/78 16 1.5 0.8 12/78 100 0/78 N4

TRPH C6 - C10 (minus BTEX) 37/78 90 19 60 2/78 4400 0/78 N

TRPH >C10 - C16 43/78 3170 598 330 16/78 3300 0/78 N4

ANALYTE

No. 

Detects Max Detect

95% 

UCL3

RBSL1 for High 

Value 

Ecological 

Areas

No. 

> RBSL1

Background 

Range

RBSLADJ2

(adjusted for 

background)

COPC

(95% UCL 

> RBSLADJ)

Barium 27/27 400 230 330 3/27 100 - 3000 330 N

Cadmium 14/27 1.7 0.37 0.77 3/27 5 - 1000 0.77 N

Cobalt 27/27 16.8 11 13 6/27 2 - 40 13 N

Manganese 27/27 715 443 220 15/27 850 220 Y

Vanadium 27/27 91 48 7.8 27/27 20 - 500 7.8 Y

Zinc 27/27 328 77 150* 1/27 100 - 300 250 - 450 N

Total Xylenes 2/27 8.4 - 1.6 2/27 n/a 1.6 Y

TRPH >C10-C16 3/27 3190 - 25 3/27 n/a 25 Y

TRPH >C16-C34 6/27 1340 - 1300 1/27 n/a 1300 N

ANALYTE

No. 

Detects Max

95% 

UCL1

No.

> RBSL2

GW 

Protectio

n RBSLADJ2

RBSL3

(adjusted 

for 

low 

permeabi

lity mud)

COPC

(95% UCL

> 

RBSLADJ3)

Antimony 11/27 0.4 0.16 2/27 0.27 2700

N

Arsenic 27/27 7.7 3.7 27/27 0.0013 13

N

Barium 15/27 400 230 2/27 120

120000

0

N

Cadmium 14/27 1.7 0.37 1/27 0.52 5200

N

Cobalt 27/27 16.8 11 27/27 0.21 2100

N

Copper 27/27 39.9 24 8/27 22 220000

N

Iron 27/27 35200 21664 27/27 270

270000

0

N

Lithium 27/27 16.1 7.7 8/27 9.3 93000

N

Manganes

e 27/27 715 443 27/27 21 210000

N

Nickel 27/27 30.2 17.3 3/27 20 200000

N

Vanadium 27/27 91 48 27/27 7.8 78000

N

Zinc 27/27 328 77 1/27 290

290000

0

N

Toluene 2/27 7.6 - 2/27

0.59

5900

N

Ethylbenze

ne

1/27 0.8

- 1/27

0.0015

15

N

orthoXylene1/27 0.9

- 1/27

0.18

1800

N

meta- & 

paraXylene

3/27 7.5

- 3/27

0.19

1900

N

Naphthale

ne

2/27 2.4

- 2/27

0.0004

7 4.7

N

TPH >C10 -

C16 

Fraction

3/27 3190 - 3/27 250 2500000 N

Formaldeh

yde

18/24

19 7.25 18/24

0.62

6200

N

Ecological RBSL Screening Results 

Residential RBSL Screening Results (mg/kg)

Groundwater Protection RBSL

Screening Results 
KEY FINDINGS

• TRPH C10-C16 fractions, total xylenes, Mn, and V exceeded ecological RBSLs 

• No direct contact or leaching to GW standards exceeded for metals or 

organics 

• The muds and cuttings are fine-grained, low permeability materials with 

organic carbon content ranging up to 2%. 

• The clay sized particles and salinity indicate the muds have a high cation

exchange capacity, which binds metals strongly within the matrix. 

• High pH limits metals in pore water and the direct phytotoxic effects of 

individual cations (metals) as the elevated metals would not be bioavailable to plants or ecological receptors

• The elevated concentrations of salts (NaCl and KCl) make drilling muds unsuitable as a direct media for plant growth.

• Drilling muds and cuttings do have potential benefits which will be explored...
BENEFICIAL USE ASSESSMENT

• When direct reuse of drilling mud is not an option – beneficial 

use of drilling muds/cuttings is preferable to off-site disposal

• Potential beneficial uses include: land spraying as 

amendment, dust suppression, subgrade material for roads, 

blending with soil for compost.

• Results of PBT and risk screening based on site specific results 

show potential risks to human health or the environment 

associated with burial or landspraying/spreading are limited
DRILLING MUDS MANAGEMENT OPTIONS

Drilling Muds 

Management 

Options Benefits

Potential Risks and 

Potential for Harm

Mitigation and 

Management 

Measures

Direct Burial

• Salts are isolated 

and encapsulated 

below the rooting 

depth of plants

• Limits impacts 

associated with 

excavation and 

transportation of 

wastes 

• Phytotoxicity due to 

excess salts 

• Burial beneath root 

zone 

• Blending with native 

soils i to reduce 

salinity of waste 

materials

• Leaching of salts or 

metals to 

groundwater 

• Avoid shallow 

groundwater

• Bury waste above 

seasonal high 

groundwater levels. 

• Grading to inhibit 

ponding

• Potential migration 

of CoPCs in surface 

water

• Project planning 

protocols: 

• Avoid surface water 

bodies, cap pits as 

soon as practical. 
DRILLING MUDS MANAGEMENT OPTIONS

Drilling Muds 

Management Options Benefits

Potential Risks and 

Potential for Harm

Mitigation and 

Management Measures

Landspreading as 

Amendment

• Provide micro and 

macronutrients (K, 

sulphate, 

phosphate, nitrate) 

for plant growth

• Alkaline nature of 

the muds could 

eliminate the need 

for application of 

lime.

• Salinity impacts on 

plants and soil 

structure 

• Potential risks to 

invertebrates or avian 

receptors from 

exposure to salts, 

manganese, 

vanadium, xylenes or 

TPH (C6-C10) fractions 

in muds.

• Mixing with shallow 

subsoils will reduce 

concentrations 

• Amendments (e.g. 

Gypsum) to reduce the 

SAR 

• Improve water 

retention capacity 

• Potential impacts on 

surface water from 

spreading close to 

water ways

• Project planning 

protocols: 

• Away from surface water

• Minimal slope

• Loading rates to mimic 

background

• Loading once/yr
MANAGEMENT OPTIONS

Drilling Muds 

Management Options Benefits

Potential Risks and Potential for 

Harm Mitigation and Management Measures

Dust Suppression

• Reduce dust generated 

during construction and 

operation

• Reduce use of water 

otherwise used for dust 

suppression.

• Improve road base

• Potential impacts on surface 

water from spreading close to 

water ways

• Planning and operations protocols 

as discussed above.

Subgrade material for 

road construction • Improved road stability 

and bearing capacity. 

• Improved compaction will 

limit future road 

maintenance activities.

• Substitute for lime and 

cement 

• Potential for runoff into 

surface water.

• Planning and operations protocols 

as discussed above.

Amendment in 

composting • Improved water retention 

capacity 

• Addition of micro/macro 

nutrients (potassium, 

sulfate, nitrate and 

phosphate) for plant 

growth.

• Potential for leaching to 

surface water

• Potential for salinity based 

impacts to plants

• Potential for ecological 

impacts

• Blending to reduce concentrations 

of salts and ensure no phytotoxic 

effects or impacts on ecological 

receptors. 

• Drilling muds with very high EC and 

SAR should be buried or disposed 

off-site.
KEY TAKEAWAYS

• In general, compounds generally not considered to be persistent or bio- accumulative in the environment and are suitable for multiple beneficial use 

options

• Beneficial use of drilling mud is a viable option with the following benefits:

• Reduce off-site disposal costs (all)

• Provision of micro and macronutrients essential for plant growth when drilling muds and cuttings 

are applied as an amendment to soils (mixbury cover and landspreading)

• Improvement of the moisture retention capacity of coarse grained and highly organic soils 

(landspreading

• Substitution for engineered materials that are more costly and would have to be trucked to the 

area for engineering projects or agricultural uses (road construction)

• Mitigation measures required to manage potential impacts (e.g. 

mixing, amendments, and planning protocols)
Understand your 

ingredient list 
THANK YOU

Thomas Silverman

Principal Hydrogeologist

EHS Support LLC

www.ehs-support.com

Tom.Silverman@ehs-support.com