Re-use: Treatment 

Technologies 

Shale Gas Water Management 

Marcellus Initiative 

Pittsburgh, PA 

Dean Ritts, PE, CEM 

Principal Engineer ± USAC 

Water 

WorleyParsons 

Houston, Texas, USA 
Water Management for Unconventional Gas

A Case Study of a Centralized Water Treatment 

System 

X 16,000 BBL Day system for Flowback and Produced 

Water 

X Under Design and will be Located In Eagle Ford Play 

X Availability of Water suitable for fracturing and the 

environmentally responsible disposal of wastewater is 

critical for sustainable development 

X Knowledge Transfer for Marcellus 
Water Management for Unconventional Gas

A Tale of Two Shale Gas Plays 

Marcellus and Eagle Ford 

X Marcellus ± Pennsylvania, USA 

x Water is generally available for hydraulic fracturing 

x Disposal is the challenge as out-of ±state disposal options 

become more costly. 

x Increasing interest in Water Re-use 
Water Management for Unconventional Gas

Eagle Ford Shale, South Texas 

x South Texas and West Texas are 

experiencing severe drought

x Water is usually sourced from 

aquifers, typically the Carrizo and 

Gulf Coast 

x Carrizo and Gulf Coast aquifers 

are major water suppliers for 

ranching, municipal and industrial 

uses including fracturing 

x Wastewater disposal in injection 

wells is readily available 
Water Management for Unconventional Gas

Management of Water Options 

X Marcellus ± Challenge of Limited Disposal 

x Reuse flowback and produced water for fracturing 

x Deep well disposal in Ohio 

x Evaporation/crystallization to remove salts 

x Treatment for metals, oil and suspended solids and discharge to 

rivers 

X Eagle Ford ± Challenge of Limited Water 

x Reuse flowback and produced water for Fracturing 

x Use brackish water from deeper aquifers (e.g. Wilcox) for 

fracturing 
Water Management for Unconventional Gas

X Hydraulic Fracturing (Gel) Fluids Contain 

x Water 

x Proppant (typically sand or silica beads) to hold fractures open 

x Salts, acids and caustics 

í to prevent /minimize clay swelling (sodium and potassium chloride, 

acids and caustics for pH adjustment) 

í to promote movement of water from the formation (methanol, 

surfactants) 

í to limit chemical changes on the fracture face that reduce 

permeability 

x Ingredients help keep the proppant in suspension (guar gums 

for gel, surfactant for slick frac solutions) 

x Crosslink enhancer (metaborate) for guar gums 

x Biocides (borates, others) 

x Chemicals to degrade the guar gum gels (pH for borates, 

oxidizers) 
Water Management for Unconventional Gas

Flowback and Produced Water 

Treatment Goals for Eagle Ford Shale 

Plays 

Treated water suitable for reuse as 

Fracturing water or for injection after 

well development is completed 

 Low suspended solids and turbidity 

 Remove polymers (guar gum) 

 Remove free and emulsified oil 

 Remove Scale-Forming Metals 

 Salts are not an issue in this applicationwater is either reused for fracturing or 

injected 
Water Management for Unconventional Gas

Flowback Water 

 Flowback water is produced 

initially in very large volume 

and is typically stored in 

portable steel tanks at the 

wellhead. 

 Flowback water is pumped to 

storage tanks or ponds and 

from there to treatment or 

disposal. 
Water Management for Unconventional Gas

Produced Water may be routed to a Centralized 

Processing Facility (CPF) for gas and condensate 

capture 

X After Pressure Let-down to near Atmospheric 

Pressure the Produced Water Contains: 

x Residual dissolved gas 

x Trace amounts of oils (condensate), both free and 

emulsified 

x Sand (amount varies from field to field) 

x Polymeric gels (floating and dispersed in water, but less 

than in flowback) 

x Higher salt content than flowback water, higher amount of 

calcium and magnesium may cause scaling problems 
Water Management for Unconventional Gas
Water Management for Unconventional Gas

Proposed Treatment ± General Issues 

x Natural gas dissolved in water / explosion hazard for 

produced wastewater 

x Variability of chemical composition of flowback water, from 

large quantity of highly viscous water (partially broken gel) 

on initial release, to more salty lower volume as gas appears 

in the water 

x 8VHRI3*UHHQ ́FKHPLFDOVIRUfracturing results in flowback 

and produced water with a high BOD (Biological Oxygen 

Demand), readily degradable 

x Anaerobic degradation of wastewater, sulfate is converted to 

hydrogen sulfide rapidly 

x Generation of finely divided ferrous sulfide solids 

x US air emission rules apply to storage/treatment tanks 

x Disposal of removed solids as slurry or as dry cake 
Water Management for Unconventional Gas

Treatment Operations 

X Primary Separation (removal of gas, sand, oil and solids) 

x Three-phase separation (gas, oil, water and solids) is 

implemented at CPF after pressure let-down to release dissolved 

natural gas 

í Some oil and most of the floating gel will pass through 

í Not required for flowback water 

x Sand Separation 

í Desanding Cyclone or Clarifier 

í May be unnecessary for flowback Water if sand is allowed to settle 

and left in portable tanks 

x Clarifier 

í Removal of floating gel and oil 

í Small amounts of sand and suspended solids 
Water Management for Unconventional Gas

X Equalization (for averaging chemical composition and 

varying flow) 

í Could be first treatment stage 

Ƈ Sand would be difficult to remove 

Ƈ Mixing is limited if oil and gel are to be removed 

Ƈ May be difficult to remove gel and oil with an overflow 

weir or other passive removal system. 

í Mixing option 

Ƈ Better averaging of variable influent stream 

Ƈ Not feasible if gel is to be removed 

í Capacity/retention time 

Ƈ Select based on variability of flow and chemical 

composition 

í Some sand will accumulate 

Ƈ Periodic manual removal required 
Water Management for Unconventional Gas

X Secondary Separation 

x Dissolved Air or Gas 

Flotation 

í Coagulant addition (iron 

or aluminum salts) and 

polymer 

í Flotation and removal of 

polymers, oils, 

suspended solids in 

floating foam 

í Very flexible system for 

removal of a wide variety 

of contaminants 
Water Management for Unconventional Gas

X Polishing and Storage 

x Filtration 

í Solids and oil polishing 

x Treated Water Storage (Pond or Tank) 

í Consider exposure of domestic and wild animals to water if stored 

in ponds 

í Bactericide addition to control bacterial growth 

x Cartridge Filtration (at injection well) 

í Not required for Fracturing 

X Sludge Management 

x Additional dewatering for collected solids 

x Possibly break gels by pH adjustment or oxidant 

x Ship off-site as slurry or as dried cake 
Water Management for Unconventional Gas

Air Pollution Control Issues 

x Treatment under Gas Blanket 

í Gas supplied by degassing from produced water and from CPF 

í Gas returned to CPF 

í Can be applied to all tanks and process vessels 

í Limits access to process vessels by operator 

í Repairs are more difficult 

x Treatment in Open Vessels or Closed with Sweep Air 

í Sweep air to air pollution control device 

í Requires air pollution controls for sweep air and ductwork to 

convey 

í Open top clarifier and DAF allow easier operator inspection and 

intervention 

x Permitting and Emissions Estimation 
Water Management for Unconventional Gas

Treatment under Reduced or Oxidized Conditions 

X Choice depends on local conditions and preference 

x Reduced 

í Typical for produced water from oil fields 

í Water is reducing upon injection; flowback and produced water is 

reducing 

í Reduced water is less corrosive than oxidized water 

í Ferrous sulfide particulate may be produced and is difficult to 

remove from suspension due to small size 

í Anaerobic sludge will be produced in the storage tanks and ponds 

due to high biodegradability and high organic content, particulate 

may require removal from water stream 

í A substantial amount of hydrogen sulfide may be produced from the 

sulfate in the wastewater 
Water Management for Unconventional Gas

Treatment under Reduced or Oxidized Conditions 

X Choice depends on local conditions and preference 

x Oxidized 

í Add an oxidant such as bleach, hydrogen peroxide 

í Due to large quantity of degradable BOD, degradation will continue 

unless some excess chlorine is maintained or a biocide is added 

í Need several addition points to maintain excess oxidant 

í Use substantial quantity of oxidant 

í Solution is more corrosive when oxidized 

í Larger quantity of some metals are removed, e.g. iron 

í May implement open top reaction vessels, especially the DAF 

í Simpler to add air in flotation process than gas in a DGF 
Water Management for Unconventional Gas

X Lessons Learned ± Gel Frac Solutions are Different 

x Sand and Gel should be removed before equalization 

x Removal of oil is not as critical as with produced water and will 

be removed with gel 

x Gel will plug v-notch weirs; utilize other designs 

x *HO3KDQJVXS ́XVHSRVLWLYHGLVSODFHPHQWGHYLFHWRLQVXUH

removal 

x A floating sludge, a sinking sludge and sand are produced; if 

mixed, thickening (removal of water) may be difficult 

x Difficult to separate and concentrate mixed sludges from water 

(floating/gel, DAF foam and settling sludges) 

x The most significant difference between produced and flowback 

water is the huge range of flows and rapid changes in chemical 

characteristics of flowback water compared with produced water 

x Oil and Gas workers are relatively inexperienced with water 

treatment 
SUMMARY 

X Shale Gas and Oil Field Development Has Challenges 

x Water Resources 

x Wastewater Treatment/Disposal 

x Environmental Compliance 

x Public Perception 

X Water Re-use is a Sustainable Engineering 

Approach to Meet the Challenge 

20 21-Mar-12

Water Management for Unconventional Gas
Water Management for Unconventional Gas

21 21-Mar-12

Thank You 

Dean Ritts, PE, CEM 

dean.ritts@worleyparsons.com