Drill Fluids and OffshoreEnvironmental ProtectionDrill Fluids and OffshoreEnvironmental Protection

John Candler, Art LeutermanJuly 2008

Overview

• Overview of drilling mud andsolids control equipment.

• Waste minimization for offshoredrilling

• Global regulation of drilling fluiddischarges.

• Drilling fluid testing, productapproval

• Global field studies of waterbased mud discharges

• Local issues for dischargesoffshore

• Overview of drilling mud andsolids control equipment.

• Waste minimization for offshoredrilling

• Global regulation of drilling fluiddischarges.

• Drilling fluid testing, productapproval

• Global field studies of waterbased mud discharges

• Local issues for dischargesoffshore

How a well is drilled usingdrilling fluids

• A drill bit designed for the expected type of formation to be drilled islowered into the well on the drill string.

• The drill string and bit are rotated by the rotary drive on the rig floor, atop drive in the derrick, or a mud motor directly above the bit which ispowered by the force of the mud flowing through it.

• The bit crushes or grinds the rock beneath it into pieces called cuttings

• Drilling Mud is circulated down the drill pipe and through openingscalled “jets” in the bit.

• The mud washes the formation cuttings from beneath the bit andcarries them to the surface.

• When the bit fails or wears out, all of the drill string must be pulledfrom the hole to replace it. This is called a trip.

• 25% - 50% of the time on location is used for non-drilling activitiessuch as running casing and tripping for new bits

• A drill bit designed for the expected type of formation to be drilled islowered into the well on the drill string.

• The drill string and bit are rotated by the rotary drive on the rig floor, atop drive in the derrick, or a mud motor directly above the bit which ispowered by the force of the mud flowing through it.

• The bit crushes or grinds the rock beneath it into pieces called cuttings

• Drilling Mud is circulated down the drill pipe and through openingscalled “jets” in the bit.

• The mud washes the formation cuttings from beneath the bit andcarries them to the surface.

• When the bit fails or wears out, all of the drill string must be pulledfrom the hole to replace it. This is called a trip.

• 25% - 50% of the time on location is used for non-drilling activitiessuch as running casing and tripping for new bits

Types of Drilling Fluids• Water Based Muds

(WBMs)– Aqueous Based Fluids– Spud- muds

– PHPA muds

– KCl / Glycol systems

– Silca systems

• Oil Based Muds(OBMs)

- Non-AqueousBased Muds(NAF)

- Diesel Oil- Mineral Oil

• Synthetic BasedMuds (SBMs)

- Non-AqueousBased Muds (NAF)

- Esters- Olefins- Paraffins

• Water Based Muds(WBMs)

– Aqueous Based Fluids– Spud- muds

– PHPA muds

– KCl / Glycol systems

– Silca systems

• Oil Based Muds(OBMs)

- Non-AqueousBased Muds(NAF)

- Diesel Oil- Mineral Oil

Water Based Muds

• Function / Sources of pollution– Controlling Sub surface pressures - Weight materials

– Removing Cuttings - Clays and polymers suspend solids

– Filtration Properties - Fluid loss reducers, polymers seal formations

– Lubricity - Lubricants - Glycols, friction reducers

– Other - corrosion, lost circulation, hydrate inhibitors

• Limitations/ Developments– Shale Inhibition

– Effective Lubricity

– Temperature Limitations

– Gas Hydrate Formation

– Drilling Efficiencies - days on location

• Function / Sources of pollution– Controlling Sub surface pressures - Weight materials

– Removing Cuttings - Clays and polymers suspend solids

– Filtration Properties - Fluid loss reducers, polymers seal formations

– Lubricity - Lubricants - Glycols, friction reducers

– Other - corrosion, lost circulation, hydrate inhibitors

• Limitations/ Developments– Shale Inhibition

– Effective Lubricity

– Temperature Limitations

– Gas Hydrate Formation

– Drilling Efficiencies - days on location

Non-Aqueous Based Muds• Function/ Sources of Pollution

– Weight materials - barite

– Viscosity - provided by invert emulsion and clay

– Filtration Properties provided by Emulsion

– Lubricity provided by base fluid

• Limitations and developments– High Cost/cubic meter

– Physical properties

– Reduced Logging Quality

– Lost Circulation

– Environmental Concerns

• Function/ Sources of Pollution– Weight materials - barite

– Viscosity - provided by invert emulsion and clay

– Filtration Properties provided by Emulsion

– Lubricity provided by base fluid

• Limitations and developments– High Cost/cubic meter

– Physical properties

– Reduced Logging Quality

– Lost Circulation

– Environmental Concerns

Solids Control Equipment

Selection of Drilling Fluids• SAFETY/ENVIRONMENTAL

– APPROVED CHEMICALS

– LOW ENVIRONMENTAL IMPACT

• TECHNICAL– FORMATION PRESSURE CONTROL

– HYDRATE PREVENTION

– ABILITY TO REACH WELL OBJECTIVES

– PRODUCTION QUALITY

– LOGGING QUALITY

– PREVENTION OF DRILLING PROBLEMS

– TEMPERATURE STABILITY

• .ECONOMIC– COST OF MUD SYSTEM TO ACHIEVE $/m, m/DAY GOALS

– EFFICIENCY OF DRILLING OPERATION- MINIMISE DAYS

• SAFETY/ENVIRONMENTAL– APPROVED CHEMICALS

– LOW ENVIRONMENTAL IMPACT

• TECHNICAL– FORMATION PRESSURE CONTROL

– HYDRATE PREVENTION

– ABILITY TO REACH WELL OBJECTIVES

– PRODUCTION QUALITY

– LOGGING QUALITY

– PREVENTION OF DRILLING PROBLEMS

– TEMPERATURE STABILITY

• .ECONOMIC– COST OF MUD SYSTEM TO ACHIEVE $/m, m/DAY GOALS

– EFFICIENCY OF DRILLING OPERATION- MINIMISE DAYS

Waste Minimization for DrillingFluids and Cuttings

Waste Minimization for DrillingFluids and Cuttings

Sources of Pollution from Offshore Drilling

Discharges to Air

Discharges to Land

Discharges to Water

Waste Management and Minimization Approaches

• Improve performance of drilling fluids and solids controlequipment:– Gauge Hole reduces waste volume

– Less shale hydration means less dilution required

– Improved Solids Control efficiency means less dilutionrequired.

• Reduced drilling problems reduces days on location andassociated discharges.

• Improved drilling efficiency reduces days on location andassociated discharges

• Drilling efficiency and waste minimization go hand in hand.

• Improve performance of drilling fluids and solids controlequipment:– Gauge Hole reduces waste volume

– Less shale hydration means less dilution required

– Improved Solids Control efficiency means less dilutionrequired.

• Reduced drilling problems reduces days on location andassociated discharges.

• Improved drilling efficiency reduces days on location andassociated discharges

• Drilling efficiency and waste minimization go hand in hand.

Waste Management Options

General Considerations for Waste Management Options

Marine Transport and Onshore Disposal Considerations

Injection Considerations

Offshore Discharge Considerations

Global WBM regulationsGlobal WBM regulations

OSPAR• Oslo and Paris Commissions (OSPARCOM) OSPAR

• Harmonized mandatory control scheme (HMCS)

• CHARM (Chemical and Risk Management) model.

• HCMS results in management decisions based on assessment of theprocess with the following outcomes:– Permission

– Substitution

– Temporary Permission

– Refusal of Permission

Test function Applicability of test

• Oslo and Paris Commissions (OSPARCOM) OSPAR

• Harmonized mandatory control scheme (HMCS)

• CHARM (Chemical and Risk Management) model.

• HCMS results in management decisions based on assessment of theprocess with the following outcomes:– Permission

– Substitution

– Temporary Permission

– Refusal of Permission

Log Pow (Mandatory)

Aerobic biodegradability (Mandatory for all organicsubstances)

Algae test (Mandatory)

Crustacean test (Mandatory)

Fish test (Mandatory)

US EPA - Offshore

• Effluent Limitation Guidelines

• General Permits by EPA RegionsIV,VI, IX, X

• Stock Limitations for Barite andBase Fluids

• End of Pipe Limits for:– Free Oil

– Sediment Toxicity

– Water column Toxicity

– Formation Oil Contamination

Requirement Categories Permit Discharge Limit

Free Oil No free oil (i. e. no static sheen)

Mercury/Cadmium Content of Stock

Barite

1.0 mg/kg mercury max.; 3.0 mg/kgcadmium max.

SPP Aquatic Toxicity Testwith Mysidopsis bahia

96-hour LC50 ≥ 30,000 ppm

• Effluent Limitation Guidelines

• General Permits by EPA RegionsIV,VI, IX, X

• Stock Limitations for Barite andBase Fluids

• End of Pipe Limits for:– Free Oil

– Sediment Toxicity

– Water column Toxicity

– Formation Oil Contamination

SPP Aquatic Toxicity Testwith Mysidopsis bahia

96-hour LC50 ≥ 30,000 ppm

Sediment Toxicity Test withLeptocheirusplumulosus SBMONLY

Ratio of 96- hour LC50 ≤1.00

Formation Oil SBM Only No Discharge

No Discharge

Base Fluids Retained onCuttings (ROC) SBMOnly

≤ 6.9% IO≤ 9.4% ester or default value: 25%

Other WBM Discharge Regions

• USA– Gulf of Mexico

– California

– Alaska

• Brazil

• Trinidad

• North Sea– Norway

– UK

• Canada East Coast

• USA– Gulf of Mexico

– California

– Alaska

• Brazil

• Trinidad

• North Sea– Norway

– UK

• Canada East Coast

Timeline of Technology DevelopmentTimeline of Technology Development1970 1980 1990 2000

High Density BrinesHigh Density Brines

LTOBMLTOBMInvert dieselInvert diesel

KCl/PHPAKCl/PHPA

Gyp/polyGyp/polyAl/polyAl/poly

Cr free HTWBMCr free HTWBM

SBMSBM

DrillDrill--in WBMin WBM

UHT WBMUHT WBM

CationicsCationics

HT ResinsHT ResinsGLYCOLSGLYCOLS

POBMPOBMLOHOBM

XX--fazefaze

OSIOSI

Virtual HydraulicsVirtual Hydraulics

Low pH disp.Low pH disp. HT WBMHT WBM

Deeper DrillingDeeper Drilling Offshore ExpansionOffshore ExpansionUltraUltra--Deep DrillingDeep DrillingEnhanced RecoveryEnhanced Recovery

High Angle DrillingHigh Angle DrillingHorizontal DrillingHorizontal DrillingLarge Diameter DrillingLarge Diameter DrillingDeepwater DrillingDeepwater DrillingEnvironmentalEnvironmentalAwarenessAwareness

Extended Reach DrillingExtended Reach DrillingUltraUltra--Deepwater DrillingDeepwater DrillingNonNon--Damaging DrillingDamaging DrillingDepleted Zone DrillingDepleted Zone DrillingOpen Hole CompletionsOpen Hole CompletionsEnvironmental ResponsibilityEnvironmental ResponsibilitySubSub--Salt DrillingSalt Drilling

Gyp/polyGyp/polyAl/polyAl/poly

Gas Hydrate TechnologyGas Hydrate Technology

DrillDrill--in WBMin WBM

SilicatesSilicates

Technology MilestonesTechnology Milestones

Advancements in Drilling TechnologyAdvancements in Drilling Technology

HT ResinsHT Resins

WBM LubricantsWBM Lubricants

Selection of Drilling Fluids• SAFETY/ENVIRONMENTAL

– APPROVED CHEMICALS

– LOW ENVIRONMENTAL IMPACT

• TECHNICAL– FORMATION PRESSURE CONTROL

– ABILITY TO REACH WELL OBJECTIVES

– PREVENTION OF DRILLING PROBLEMS

• .ECONOMIC– COST OF MUD SYSTEM TO ACHIEVE $/m, m/DAY GOALS

– EFFICIENCY OF DRILLING OPERATION- MINIMISE DAYS

• SAFETY/ENVIRONMENTAL– APPROVED CHEMICALS

– LOW ENVIRONMENTAL IMPACT

• TECHNICAL– FORMATION PRESSURE CONTROL

– ABILITY TO REACH WELL OBJECTIVES

– PREVENTION OF DRILLING PROBLEMS

• .ECONOMIC– COST OF MUD SYSTEM TO ACHIEVE $/m, m/DAY GOALS

– EFFICIENCY OF DRILLING OPERATION- MINIMISE DAYS

FIELD STUDIES

• NEED TO BE ECOLOGICALLY RELEVANT

• VERIFICATIONS OF LAB PREDICTIONS

• VARIABILITY ISSUES

• SPECIES IDENTIFICATION

• SIGNIFICANCE OF ENVIRONMENTAL FACTORS– MAJOR DIFFERENCES BETWEEN AREAS

• NEED TO BE ECOLOGICALLY RELEVANT

• VERIFICATIONS OF LAB PREDICTIONS

• VARIABILITY ISSUES

• SPECIES IDENTIFICATION

• SIGNIFICANCE OF ENVIRONMENTAL FACTORS– MAJOR DIFFERENCES BETWEEN AREAS

Geographic RegionsGrandBanks

ScotianShelf

North Sea GOM Australia

Energy HIGH HIGH HIGH - MED LOW/MED HIGH

Depth (m) 70-90 14-110 50-600

(125 m)

30 - 200

300-4000

50-80

Shllw/deep

Sediment Sand Sand Sand/fine Fine SandSediment Sand Sand Sand/fine Fine Sand

Wtr Temp Sfc -1 to 14 2 – 20 7.5 – 13 13 – 26 10 – 30

Wtr TempBottom

0 to – 0.5 < 5 3 – 8 ~ 4 NA

Currents –SFC

45 – 80 30 – 40 13 – 36 5 - > 110 10 – 70

Currents –Bottom

Usually < 4 1 – 7 NA 0 - ~ 110 NA

RECEIVING ENVIRONMENT FACTORS

• WATER TEMP

• BOTTOM TYPE

• THERMOCLINE

• CURRENT

• WATER QUALITY

• WAVE TYPE

• STORM EVENTS

• BIOTA

• WATER DEPTH

• RIVER INPUTS

• OTHER ACTIVITIES

• WATER TEMP

• BOTTOM TYPE

• THERMOCLINE

• CURRENT

• WATER QUALITY

• WAVE TYPE

• STORM EVENTS

• BIOTA

• WATER DEPTH

• RIVER INPUTS

• OTHER ACTIVITIES

WBM FIELD STUDIESWBM FIELD STUDIES

WBM FIELD STUDIES• MID-ATLANTIC (1978)

– 120 M; PHYSICAL ALT TO 150 M– ONLY BA ELEVATED– > CRABS & FISH NEARFIELD; NO CORRELATION W/ BARIUM– GENERAL LACK OF SIGNIFICANT EFFECTS

• NORTH SEA– 45 M; 2 MONTHS & 1 YEAR– CUTTINGS TO 25 M; NO TRACE IN 10 MONTHS– NO BENTHIC EFFECTS OBSERVED– HIGH ENERGY ENVIRONMENT (SIMILAR TO SABLE ISLAND)

• CALIFORNIA (JENKINS, 1989)– METAL UPTAKE STUDY– CLAM; DEPOSIT & FILTER FEEDING POLYCHAETES– NO BENTHIC EFFECTS– BA IN SEDIMENT TO 1,500 M– > BA IN CLAM & FILTER FEEDER

• > 97% GRANULAR BA SULPHATE IN CELLS

• GOOMEX– 3 PLATFORMS; MUD/CUTTINGS/PW– SHUNTING AT ONE– NO BIOACCUMULATION– IMPACTS < 200 M– PHC < 500 M; METALS TO 5 KM

• GEORGES BANK• COOK INLET• TANNER BANK• CALIFORNIA – CAMP• BEAUFORT SEA

• MID-ATLANTIC (1978)– 120 M; PHYSICAL ALT TO 150 M– ONLY BA ELEVATED– > CRABS & FISH NEARFIELD; NO CORRELATION W/ BARIUM– GENERAL LACK OF SIGNIFICANT EFFECTS

• NORTH SEA– 45 M; 2 MONTHS & 1 YEAR– CUTTINGS TO 25 M; NO TRACE IN 10 MONTHS– NO BENTHIC EFFECTS OBSERVED– HIGH ENERGY ENVIRONMENT (SIMILAR TO SABLE ISLAND)

• CALIFORNIA (JENKINS, 1989)– METAL UPTAKE STUDY– CLAM; DEPOSIT & FILTER FEEDING POLYCHAETES– NO BENTHIC EFFECTS– BA IN SEDIMENT TO 1,500 M– > BA IN CLAM & FILTER FEEDER

• > 97% GRANULAR BA SULPHATE IN CELLS

• GOOMEX– 3 PLATFORMS; MUD/CUTTINGS/PW– SHUNTING AT ONE– NO BIOACCUMULATION– IMPACTS < 200 M– PHC < 500 M; METALS TO 5 KM

• GEORGES BANK• COOK INLET• TANNER BANK• CALIFORNIA – CAMP• BEAUFORT SEA

WBM FIELD STUDY SUMMARY

• NO SIGNIFICANT BIOACCUMULATION

• LOW TOXICITY

• LIMITED BENTHIC IMPACT– < 150 M; IMPACTS PHYSICAL

• LIMITED CUTTINGS ACCUMULATION

• NO SIGNIFICANT WATER COLUMN IMPACTS

• NO SIGNIFICANT BIOACCUMULATION

• LOW TOXICITY

• LIMITED BENTHIC IMPACT– < 150 M; IMPACTS PHYSICAL

• LIMITED CUTTINGS ACCUMULATION

• NO SIGNIFICANT WATER COLUMN IMPACTS

Local Receiving EnvironmentConsiderations

• Depth of Water

• Currents

• Local species and bottom conditions

• Depth of Water

• Currents

• Local species and bottom conditions

Conclusions• Drilling Fluids, waste management

strategies can be designed to meeta of technical, economic andenvironmental requirements.

• Significant investments have beenmade to study and understandpotential impacts from disposal ofdrilling fluids and drill cuttings.

• Many areas around the world haveachieved drilling goals combinedwith protection of the environmentwith the support of good scienceand good technology.

• Drilling Fluids, waste managementstrategies can be designed to meeta of technical, economic andenvironmental requirements.

• Significant investments have beenmade to study and understandpotential impacts from disposal ofdrilling fluids and drill cuttings.

• Many areas around the world haveachieved drilling goals combinedwith protection of the environmentwith the support of good scienceand good technology.