produced water from oil field

treatment desalination
PRESENTED TO: ENG/ SH. HADARA
PRESENTED BY:
(1) Mohamed Fath-Allah Mahmoud El-Sharnouby
(2) Mohamed Mostafa Kamel Mohamed Hashish
(3) Mahmoud Housien Hassan Elhlwany
(4) Mostafa Ali Twfek Ali

| Diploma |7/12/2107
Introduction

Oil is one of the main energy sources of worldwide and its production is a very
essential issue. While oil is produced, some unfavorable effects in the environment occur.
Produced water, which is produced during oil production, is one of the most important
sources of unfavorable effects. Volume of this wastewater is around 70% of total
wastewater produced during oil production. In many instances, this waste stream is seven
to eight times greater by volume than oil produced at any given oilfield.
Produced water is separated from oil or gas at the head of the production well.
While 65% of this water is re-injected to the well for pressure maintenance, 30% of total
is injected to deep well for final disposal in the case of proper aquifer conditions and the
rest of the water is discharged to surface water. The water, which is not re-injected to the
production well, has to be treated.
Feeding groundwater, irrigation and maintaining wetland habitats are the potential
options for reuse. Additionally, the water re-injected to the well must also be treated due
to effects on the reservoir composition. Sometimes an aquifer having appropriate formation
conditions cannot be available.
Produced water has distinctive characteristics due to organic and inorganic matters.
It includes largely salts and oil hydrocarbons which may be toxic to environment. Produced
water is variable and can be very different by well to well. Besides, characteristics of
produced water from oil and gas fields can also be very variable.
Many studies have been carried out on produced water from oil fields. Physical and
chemical separation processes such as coagulation, acidification and membrane processes
have been performed. However, these processes alone did not provide the petroleum waste
discharge standards.
Successful treatment of produced water generally requires a series of pre-treatment
operations to remove different contaminants. Separation techniques that have been tested
for the removal of oil, grease, and suspended solids from produced water include walnut
shell filtration, fiber ball media filtration, gravity-type cross flow pack separation, ceramic
cross flow microfiltration and ultrafiltration. Removal of organic compounds from
produced water is carried out by electro flocculation, adsorption, bioreactors, wetlands,
ultrafiltration, Nano filtration and reverse osmosis. After appropriate pre-treatment, the
high total dissolved solids (TDS) can be removed from produced water by reverse osmosis.

1. What Is Produced Water?

In subsurface formations, naturally occurring rocks are generally permeated with fluids
such as water, oil, or gas (or some combination of these fluids). It is believed that the rock
in most oil-bearing formations was completely saturated with water prior to the invasion
and trapping of petroleum (Amyx et al. 1960). The less dense hydrocarbons migrated to
trap locations, displacing some of the water from the formation in becoming hydrocarbon
reservoirs. Thus, reservoir rocks normally contain both petroleum hydrocarbons (liquid and
gas) and water. Sources of this water may include flow from above or below the
hydrocarbon zone, flow from within the hydrocarbon zone, or flow from injected fluids
and additives resulting from production activities. This water is frequently referred to as
“connate water” or “formation water” and becomes produced water when the reservoir is
produced and these fluids are brought to the surface.
Produced water is any water that is present in a reservoir with the hydrocarbon resource
and is produced to the surface with the crude oil or natural gas.

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 When hydrocarbons are produced, they are brought to the surface as a produced
fluid mixture. The composition of this produced fluid is dependent on whether crude oil or
natural gas is being produced and generally includes a mixture of either liquid or gaseous
hydrocarbons, produced water, dissolved or suspended solids, produced solids such as sand
or silt, and injected fluids and additives that may have been placed in the formation as a
result of exploration and production activities.
Production of coal bed methane (CBM) involves removal of formation water so that the
natural gas in the coal seams can migrate to the collection wells. This formation water is
also referred to as produced water. It shares some of the same properties as produced water
from oil or conventional gas production, but may be quite different in composition.

2. Produced Water Characteristics

Produced water is not a single commodity. The physical and chemical properties of
produced water vary considerably depending on the geographic location of the field, the
geological formation with which the produced water has been in contact for thousands of
years, and the type of hydrocarbon product being produced. Produced water properties and
volume can even vary throughout the lifetime of a reservoir. If water flooding operations
are conducted, these properties and volumes may vary even more dramatically as additional
water is injected into the formation.
Understanding a produced water’s characteristics can help operators increase
production.
For example, parameters such as total dissolved solids (TDS) can help define pay zones
(Breit et al. 1998) when coupled with resistivity measurements. Also, by knowing a
produced water’s constituents, producers can determine the proper application of scale
inhibitors and well-treatment chemicals as well as identify potential well-bore or reservoir
problem areas (Breit et al. 1998).

3. Major Components of Produced Water

The basic components of produced water can be grouped into the following main
categories: oil, heavy metals, radionuclides, treating chemicals, Produced Solids, Scales,
salt, and dissolved oxygen.

4. Factors Affecting Produced Water Production and Volume

The following factors can affect the volume of produced water during the life cycle of a well
(Reynolds and Kiker 2003). This is not intended to be an all-inclusive list but merely a
demonstration of the potential impacts.
 Type of well drilled
A horizontal well can produce at higher rates than a vertical well with a similar drawdown or can
produce at similar rates with a lower drawdown, thus delaying the entry of water into the well bore
in a bottom water drive reservoir.
 Location of well within reservoir structure
An improperly drilled well or one that has been improperly located within the reservoir structure
could result in earlier than anticipated water production.
 Type of completion
A perforated completion offers a greater degree of control in the hydrocarbon-producing zone.
Specific intervals can either be targeted for increased hydrocarbon production or avoided or
plugged to minimize water production.

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  Type of water separation and treatment facilities
Historically, surface separation and treatment facilities have been used for produced water
management. However, this type of operation involves lifting costs to get the water to the surface
as well as equipment and chemical costs for treatment of the water. Once on the surface,
introduction of oxygen into the produced water treatment environment requires that corrosion and
microbial issues be addressed. Alternatives to surface treatment could be downhole separation
equipment that allows the produced water to remain downhole, thereby avoiding some of the lifting,
surface facility, and corrosion costs and issues.
 Water flooding for enhanced oil recovery
The basic purpose of water flooding is to put water in the reservoir where the oil is located so that
it will be driven to a producing well. As the water flood front reaches a producing well, the volume
of produced water will be greatly increased. In many instances, it is advantageous to shut in these
producing wells or convert them to injection wells so as not to impede the progression of the water
front through the reservoir.
 Insufficient produced water volume for water flooding
If insufficient produced water is available for water flooding, additional source waters must be
obtained to augment the produced water injection. For a water flood operation to be successful, the
water used for injection must be of a quality that will not damage the reservoir rock. In the past,
freshwater was commonly used in water floods. Because of increasing scarcity, freshwater is
typically no longer used as a viable source water for water flooding. Regardless of the source, the
increased addition of this water to the reservoir will result in an increased volume of produced
water.
 Loss of mechanical integrity
Holes caused by corrosion or wear and splits in the casing caused by flaws, excessive pressure, or
formation deformation can allow unwanted reservoir or aquifer waters to enter the well bore and
be produced to the surface as produced water.
 Subsurface communication problems
Near-well bore communication problems such as channels behind casing, barrier breakdowns, and
completions into or near water can result in increased produced water volumes. Additionally,
reservoir communication problems such as coning, cresting, channeling through higher
permeability zones or fractures, and fracturing out of the hydrocarbon producing zone can also
contribute to higher produced water volumes.
Each of the above factors can greatly affect the volume of produced water that is ultimately
managed during the life cycle of a well and project. With increased produced water volumes, the
economic viability of a project becomes an issue, due to the loss of recoverable hydrocarbons, the
added expense of lifting water versus hydrocarbons, the increased size and cost of water treating
facilities and associated treatment chemicals, and the disposal cost of the water. With the
consideration of water impacts to a project, proper planning and implementation can minimize
these expenses or at least delay their impact.
5. Produced Water Volumes
In 2007, U.S. onshore and offshore oil and gas production activities generated nearly 21
billion barrels of produced water. The next Table provides production information for U.S.
Produced Water Volume by Management Practice for 2007.

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 6. Produced Water Management Options
Water treatment technologies offer opportunities for the oil and gas industry to reuse
flow back water from hydraulic fracturing applications. This water reuse by the oil and gas
industry offsets fresh water requirements and reduces demand on regional water systems.
Recent advancements in energy production technology, such as horizontal drilling,
have greatly increased natural gas production in the United States. Hydraulic fracturing for
gas production requires significant quantities of water per well site, making sustainable and
available water supplies critical aspects of oil and gas well development. Furthermore,
wells from horizontal drilling require more water than traditional vertical wells.
Oil and gas extraction also creates substantial quantities of “produced” waters with
varying levels of contamination, which must be disposed through treatment or reinjection.
Produced water coexists naturally with oil and gas deposits and is brought to
the surface during well production. Produced water is extracted at an average rate of 2.4
billion gallons per day (gpd), and over 80 percent of production occurs in the Western U.S.
(Clark and Veil, 2009). Produced water represents the largest waste stream associated with
oil and gas production with estimates of almost 2.7 million acre feet per year.
Produced water is commonly re-injected for disposal due to its salinity, but in water
stressed areas, this water can be treated and managed for uses such as:
 Well drilling or hydraulic fracturing
 Emergency drought supply
 Livestock water
 Irrigation water
 Surface water augmentation
 Drinking water applications
Most produced water requires treatment to make it suitable for recycling or beneficial
use. Produced water varies widely in quantity and quality, depending on the method of
extraction, type of oil and gas reservoir, geographical location, and the geochemistry of
the producing formation. Therefore, many different types of technologies exist to treat
produced water. Also, advanced water treatment technology can be used for:
 Treating alternative water sources for hydraulic fracturing
 Internal industry reuses on-site at decentralized facilities
 Beneficial use of produced water and flow back water for alternative applications
off-site Treatment

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 7. Water Management Costs
Costs for water management in the oil and gas industry are highly variable. Cost
calculations for water sourcing, transportation, storage, treatment, and disposal are not
commonly presented on a whole-cost basis. Comparison between management costs is thus
difficult to quantify. General ranges of costs are presented as a basis for understanding the
relative cost of water management. Costs included in this section represent ranges of costs
documented in the Government Accountability Office report (2012).
 Transportation
Water transportation is required to move water on-site for well development and off-site
for treatment or disposal. Trucking costs may range from $0.50 to $8.00 per barrel (bbl)
depending on the state and transportation distance.
 Water Sourcing
Water required for well development may be purchased for use from local landowners or
municipalities for $0.25 to $1.75 per bbl (Boschee, 2012).
 Disposal
Disposal is commonly managed through injection wells with costs for underground
injection ranging from $0.07 to $1.60 per bbl of produced water. Options such as
impoundments or evaporation ponds are not always available due to permitting
restrictions.
 Treatment
Treatment costs both on-site and off-site vary considerably based on technology, water
quality, and end use. Estimates depend on the site location and type of project and range
from $0.20 to $8.50 per bbl.

8. Summary of Treatment Technologies

This section introduces treatment technologies currently used in the oil and gas
industry. Information provided for each technology category includes a brief description
of the technology, applicable contaminants removed, application with removal
mechanisms, and a qualitative summary of benefits and limitations. For additional
information on these technologies, additional emerging technologies, and a comprehensive
list of specific industry technology combinations
 Pretreatment technologies
Pretreatment technologies are categorized as technologies that remove constituents such as
suspended solids, oil and grease, and organic matter. Pretreatment technologies generally
precede desalination technologies to protect downstream processes from clogging and
damage.
 Settling Pond
 Plate Settler
 Hydro cyclone
 Dissolved Air Flotation
 Electrocoagulation/Electro floatation
 Microfiltration/Ultrafiltration
 Bioreactors
 Evaporation
 Crystallizer
 Ion Exchange

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 9. Desalination Technologies
Desalination technologies are necessary to lower the total dissolved solids
concentration and the concentration of ions that are too high for the desired beneficial use
of co-produced water. Desalination technologies fall into the following categories:
 Membrane.
 Thermal.
 alternative technologies.
Desalination technologies, combined together and called hybrid technologies, are often
employed to reduce the energy cost of the process or to enhance the product water recovery.
The following membrane processes were evaluated:
 reverse osmosis.
 Nano filtration.
 electro dialysis (ED).
Hybrid membrane processes considered are
 two pass Nano filtration.
 dual RO with chemical precipitation.
 dual RO with HERO™.
 dual RO with seeded slurry precipitation.
 high efficiency electro dialysis.
The thermal desalination technologies included in this report are:
 membrane distillation.
 multistage flash distillation.
 multieffect distillation.
 vapor compression.
The technologies were evaluated based on the whether they are an emerging technology or
an established technology and whether they previously have been employed for treatment
of produced water. The total dissolved solids (TDS) range of applicability of these
technologies and their salt rejection and product water recoveries are also presented.
Specific sodium, organic, and heavy metal rejection capabilities are also presented. The
technologies then were compared qualitatively based on the following criteria:
 pretreatment requirements.
 chemical and energy requirements.
 maintenance requirements.
 ease of operation.
 Cost.
 Robustness.
 Reliability.
 Flexibility.
 Mobility.
 Modularity.
 volume of residuals generated.
 the size of the plant or footprint.

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 Membrane Treatment Technologies
A variety of membrane technologies can remove dissolved contaminants. Both
ultrafiltration and microfiltration membranes were listed under the pretreatment category,
this section focuses mainly on common desalination membrane processes

-
 Reverse Osmosis
Osmosis, an integral part of the functioning of all living cells, is a phenomenon in which
a liquid (water in this case) passes through a semi-permeable membrane from a relatively
dilute solution toward a more concentrated solution. This flow produces a measurable
pressure, termed osmotic pressure. If, however, pressure is applied to the more
concentrated solution that exceeds the osmotic pressure, water flows through the
membrane from the more concentrated solution to the dilute solution (Figure). This
process, reverse osmosis, results in two streams of water: one relatively large volume with
a low concentration of dissolved impurities (permeate), and one relatively small volume
with a high concentration (reject).

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  Electrodialysis/Electrodialysis Reversal

Electrodialysis is an electrically driven process consisting of a stack of alternating

cation-transfer membranes and anion-transfer membranes between an anode and a cathode.
An electrical current is passed through the water. The dissolved salts in the water exist as
ions and migrate toward the oppositely charged electrode. The anion-transfer membrane
only allows passage of negatively charged ions, and the cation-transfer membrane only
allows passage of positively charged ions. Alternating anion and cation transfer membranes
are arranged in a stack. The membranes are impermeable to water. These systems are
operated at a very low pressure, usually below 25 psi. Electrodialysis reversal also can be
implemented where the charge on the electrodes is frequently reversed. This prevents
buildup of scale, biofilm, and other foulants on the membrane surface.

The energy required for ED treatment is related to the TDS of the water—the higher
the TDS, the more energy required for treatment. Current research suggests that ED is not
cost competitive for treating water with a TDS greater than 1,500 mg/L. Sirivedhin et al.
tested ED on five simulated produced water types of high and low TDS using Neosepta®
membranes. They found that at 6.5 volts per stack, ED was not capable of producing water
with an SAR that would be suitable for irrigation because ED removes divalent ions to a
greater extent than monovalent ions (Sirivedhin, McCue et al. 2004). If ED, using divalent
selective membranes, is to be used to treat produced water for beneficial use as irrigation
water, calcium and/or magnesium will need to be added back to the water to lower the
sodium absorption ratio (SAR).

Hybrid Membrane Processes

 Two Pass Nanofiltration
Two pass nanofiltration involves treating produced water with nanofiltration and then
further treating the permeate water with nanofiltration again. This process is used to obtain
a permeate stream with an even lower TDS than a single pass NF process and is less energy
intensive than reverse osmosis. Western Environmental pilot tested this process for
produced water (Bierle).
 Dual RO with Chemical Precipitation
Dual RO with chemical precipitation consists of a primary RO process. The concentrate
from the first RO is further treated with lime softening and is then fed to a second stage
RO. The permeate streams from both RO processes are collected and provide the product
water from this process. Reported recoveries using this process are 95% and higher for
brackish water applications. Utilizing this process enhances the recovery of the RO process
but requires additional chemicals, additional equipment, and an increased footprint.
 Dual RO with Softening Pretreatment and Operation at High pH
This patented process is called HERO™ and consists of chemical softening as a
pretreatment step, primary RO, and ion exchange, degasification, and pH increase on the
concentrate from the first RO stage. The treated concentrate stream then is treated with a
secondary RO. The product water from the primary and secondary RO units is combined
to make up the product water for this process. As with the dual RO with chemical
precipitation, this process is designed to increase the product water recovery of the process.
Reported recovery rates range from 90–95%.

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  Dual RO with Slurry Precipitation and Recycling RO (SPARRO)
In this process, a single stage reverse osmosis membrane unit is used, and the concentrate
from the RO process is treated using a seeded crystalline slurry to precipitate sparingly
soluble salts from the water. The crystals then are separated from the concentrate process
stream using a cyclone separator, and the remaining water then is recycled back to the RO
feed.
 High Efficiency Electrodialysis (HEED®)
HEED® is an electromembrane process in which the ions are transported through a
membrane from one compartment to another under the influence of an electrical potential.
HEED® consists of dual or multiple side-by-side ion exchange membranes and contains
an improved gasket design that results in greater efficiency than traditional ED processes
(Corporation 2008). HEED® is more resistant to organic fouling than RO or NF.

Thermal Processes Technologies

 Multistage Flash Distillation
Multistage flash distillation converts water to steam at low temperatures in a vacuum. At
vacuum pressures, the boiling point of water is lower than at atmospheric pressure,
requiring less energy. The water is preheated and then subjected to a vacuum pressure that
causes vapor to flash off the warm liquid. The vapor then is condensed to form fresh water
while the remaining concentrated brine that does not flash is sent to the next chamber where
a similar process takes place. The multiple stages are designed to improve the recovery of
the process. Many of the older seawater desalination plants use the multistage flash
distillation process.
 Multieffect Distillation
In multieffect distillation, vapor from the first evaporator is condensed in the second
evaporator and the heat of condensation is used to evaporate the water in the second
evaporator. Each evaporator in the series is called an “effect.”
 Vapor Compression
In the vapor compression process, the feed water is preheated in a heat exchanger by the
product and reject streams from the process. This process uses a still that contains tubes.
The water then is fed to the inside of the tubes, and the vapors then are fed to the outside
of the tubes to condense. The gases that do not condense are removed from the steam-
condensation space by a vent pump or ejector. The mechanical pump or ejector is a
requirement of this process and is necessary to increase the pressure of the vapor to cause
condensation. Vapor compression has been used for produced water treatment, and
commercially available products currently are marketed for this application.
 Membrane Distillation
Membrane distillation is a thermally driven membrane processes that uses the vapor
pressure gradient between the feed solution and the product solution as the driving force.
The membrane is hydrophobic and microporous. The flux and salt rejection of this process
is independent of feed water salinity. There are many different configurations for the
application of membrane distillation.

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 Alternative Desalination Processes
Alternative desalination processes do fall within the thermal or membrane categories and
use other materials and mechanisms for desalination.
 Capacitive Deionization
In capacitive deionization, water is passed through pairs of high surface area carbon
electrodes that are held at a potential difference of 1.2 volts. Ions and other charged
particles are attracted to the oppositely charged electrode. When the electrodes have
become saturated with ions, they must be regenerated by removing the applied potential
and rinsing the ions out of the system.
The carbon aero gel electrodes have a relatively high surface area (500 m2/g) and provide
high electrical conductivity, and have a high ion permeability. The electrodes are, however,
expensive and have a relatively low ion storage capacity.
 Softening
Softening can be used to remove hardness and silica from the water. Generally, if the water
is to be used for agricultural purposes, softening would not be advised because, like
nanofiltration, the SAR will be higher following treatment due to removing the divalent
ions.
 Ion Exchange
The Higgins Loop™ is a sodium ion exchange technology for water with a high
concentration of sodium. This process is beneficial if there are no other ions of concern
besides sodium and if SAR adjustment is necessary. The cation exchange resin in the
Higgins Loop™ process exchanges sodium ions for hydrogen ions. Up to 90% exchange
levels are achieved. As the resin becomes loaded with sodium, the flows to the adsorption
portion of the process temporarily are interrupted. The resin then is advanced by a pulsing
action through the loop in the opposite direction of the liquid flow. The loaded resin then
is regenerated with hydrochloric acid and rinsed before being advanced back into the
adsorption portion of the loop. Treated water is slightly acidic because H+ ions are added
to the water. Therefore, the pH is raised, and calcium is added by passing the treated water
through a limestone bed in the pH controlling process step.
For many produced waters, removing the sodium ions will have a large effect on the total
dissolved solids concentration to render the water suitable for beneficial use.
Other ion exchange resins also may be employed to target specific ions for removal. The
resin may or may not be able to be regenerated.

References

 ALL Consulting, LLC. Water Treatment Technology Catalog and Decision Tool
www.all-llc.com/projects/produced_water_tool Accessed February 2014.
 Boschee, P., 2012.Handling Produced Water from Hydraulic Fracturing. Oil and
Gas Facilities Editor, February, 2012
www.spe.org/ogf/print/archives/2012/02/02_12_10_Feat_Water_Hydraulic.pdf.
Accessed February 2014.
 Cath, T.Y., J.E. Drewes, and C.D. Lundin. 2009. A Novel Hybrid Forward
Osmosis Process for Drinking Water Augmentation using Impaired Water and
Saline Water Sources. WERC and Water Research Foundation. ©Water Research
Foundation and Arsenic Water Technology Partnership2009.
www.waterrf.org/PublicReportLibrary/4150.pdf. Accessed July 2014.

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 Clark, C.E. and J.A. Veil, 2009. Produced Water Volumes and Management
Practices in the United States. ANL/EVS/R-09/1. Accessed February 2014.
Colorado School of Mines, Kennedy/Jenks Consultants, and Argonne National
Laboratory, nd. CBM Produced Water Management Tool
http://www.aqwatec.mines.edu/produced_water/tools/. Accessed February 2014.

 Dahm, K., 2014. Guidance for the Evaluation of Water Management Strategies to
Provide Regional Water Supplies for the Oil and Gas Industry. Manuals and
Standards Project Number 4097. Accessed March 2014.
 Dahm, K. and K Guerra, 2014. Produced Water Reuse Case Studies. Presentation
at EUCI: Produced Water Management in the West Conference, May 21st, 2013.
www.usbr.gov/research/projects/detail.cfm?id=1617. Accessed February 2014.
 Degrémont, S.A., 1991, Water Treatment Handbook. Lavoisier Publishing.
 DeSilva, F., 2005. Measures to Reduce Uranium in the Drinking Water Supply.
Water Quality Products, April 6, 2005. www.wqpmag.com/uranium-removal-ion-
exchange. Accessed July 2014.

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