Technology Status Assessment of
“Cost Effective Treatment of Produced Water Using Co-Produced
Energy Sources for Small Producers”
1. Problem Statement
Produced water embodies the primary waste stream of oil, natural gas and coalbed
methane production. It is very saline, sometimes nearly six times as salty as seawater, and
contains dissolved hydrocarbons and organic matter as well. For many small oil/gas producers,
purification of the produced water at the wellhead, and on-site disposal or use of the purified
water for beneficial uses such as well drilling and stimulation, will be the primary options for
cost-effective produced water management, due to the shortage of storage capacity and
limitations of distribution technologies. Deployment of advanced technologies for removing salts
and dissolvable organics is generally required for attaining surface water discharge standards or
reuse criteria.1 However, numerous experiments and demonstration tests have indicated that no
cost-effective technologies can effectively remove the dissolved components due to the
complexity of water chemistry and variability in water volume. As a result, the bulk of produced
water (>90%) is currently managed through a three-step process: (1) lifting produced water to the
surface, (2) transportation to the disposal site, and (3) deep well injection or evaporation.2 The
average disposal cost for produced water in New Mexico is ~2.5$/bbl, with a major part of this
cost attributed to its transportation in most of the producing areas of New Mexico.2 The
economic burden posed by produced water disposal can mean uneconomical production from
otherwise viable wells, particularly marginal wells, forcing producers to abandon these operations.
Development of a method that can be deployed for cleaning produced water at the wellhead is
2. Current State of Technology
A. Summary of Background of Industry/Sector
Water issues are closely connected with and have significant impacts upon the economic
viability of oil and gas production. To purify produced water to substantial quality suitable for
beneficial uses such as well drilling, stimulating or land revegetation, efforts have been focused
on demineralization and organic removal.3 The demineralization technologies include reverse
osmosis (RO), distillation, electrodialysis, freeze-thawing desalination, and ion exchange4; air
stripping, activated carbon adsorption, membrane filtration, biological treatment and wet air
oxidation have been widely investigated for dissolved organic removal.5 Unfortunately, the
applications of these technologies are highly limited due to environmental sensitivity (i.e., freeze-
thawing) and energy intensity caused by floating oil and hydrocarbons (i.e., reverse osmosis and
electrodialysis).6 Other factors such as feed water chemistry, water volume, and additives in
produced water also show considerable influence on the process design and technology
deployment.7 Even with the rapid advancement in water desalination technology and tremendous
efforts in produced water purification, no process was reported to be cost-effective for produced
water desalination. The desirable technology needs to be tolerant of the large variations in feed
water quality and water volume for deployment at wellhead.
Humidification-dehumidification is a heat-based desalination process involving enhanced
water evaporation in the presence of flowing air and water condensation upon subsequent cooling
or capillary condensation. The typical characteristics of the humidification-dehumidification
process include flexibility in capacity, atmospheric pressure operation, and use of low-
temperature energy such as solar energy, geothermal, and waste heat from industries. Such a
water desalination process is based on the fact that air can carry large amounts of water vapor at
elevated temperatures. For example, by increasing temperature from 30 to 80C, 1 kg air can
carry 0.52 kg water vapor; about 500 g clean water could be collected upon subsequent cooling. 8
Taking into consideration the general humidification and dehumidification process for producing
1.0 kg clean water, the energy consumption of water heating, evaporation, and air blowing are
209 kJ, 2260 kJ and 8 kJ respectively, wherein over 90% of energy consumption is for the phase
conversion. To overcome the high energy consumption during phase conversion process, the
latent heat released by the dehumidification process could be deployed for feed water preheating. 8
A limitation of the referenced desalination process is the low water recovery and high sensitivity
to heat loss.9 Recently, Beckman and coworkers reported a dewvaporation process for
enhancement of latent heat recovery and improvement of energy efficiency.10
B. Technologies/Tools Being Used
In the proposed research, a demonstration of a low-temperature distillation unit with a
built-in dehumidifier will be constructed for produced water purification. The use of solar energy
for water heating is particularly designed for application in areas with abundant solar radiation,
such as New Mexico. In addition, this water purification system can use co-produced energy
sources to drive the desalination process, in which a considerable decline in electricity
consumption is expected. Field tests of produced water purification will be performed for over
one year at two sites: Fed 00 #3 and Floyd #2, both in New Mexico. Our industry partners,
Harvard Petroleum Corp. and Robert L. Bayless, Producer LLC., will devote considerable efforts
to support NMT on the field demonstration, including site use, demonstration setup, and water
B.1. Technology/Tool 1：Humidification and dehumidification technology
The proposed low-temperature distillation process with a built-in dehumidifier and solar
collectors for wellhead produced water purification is basically composed of two system
configurations: (1) a solar collector for produced water heating; and (2) a low-temperature
distillation tower with a built-in water condenser. Produced water lifted from oil and gas wells
will be heated to elevate temperature by solar or co-produced energy sources. The heated
produced water is further directed into the low-temperature distillation unit for purification. The
separation unit includes a bundle of evaporation and condensation chambers that are stacked in
parallel and separated by thin plastic films. In the evaporation chamber, hot water drains down
from the top to form a thin water film and contacts air moving in a counter direction, forming
humidified air. The humidified air with nearly-saturated water vapor is further directed to the
cavities of the condensation chamber for clean water collection as a result of cooling and
The large amount of latent heat expected in phase conversion (i.e. water evaporation) is
the main cause of the energy intensity of conventional distillation processes. In this project,
reduction of the energy consumption required by water purification will be addressed by specific
means, including deployment of co-produced energy sources and recovery of latent heat by using
heat pumps.8, 10
B.2. Technology/Tool 2: Deployment of solar and co-produced energy sources
The first tactic for reducing electricity consumption is to deploy co-produced energy
sources or solar energy for driving the desalination process. A specific advantage of the proposed
water purification process is that various low-temperature energies can be used, such as solar
energy and co-produced geothermal energy. These low-cost energies are generally available with
oil/gas production activities in the western United States, so a considerable decline in operating
cost is expected. In addition, high solar radiation intensity and the deep reservoir formation make
it possible for deploying or integrating solar and co-produced geothermal energies for produced
water heating and desalination.11
B.3. Technology/Tool 3: Heat pump technology for enhancing latent heat recovery
Another tactic for reducing electricity consumption is to use a heat pump for enhancing
latent heat recovery. Evaporation provokes cooling on the evaporation side while water vapor
condensation provokes heat release in the adjacent chamber. Heat released by condensation will
transport to the evaporation side for enhancing water evaporation. Heat pump technology will be
deployed for further cooling the condensation chamber to a low temperature and recovering the
latent heat for feed water preheating.
4. Development Strategies
A. Justification for new research or technology
Even with the rapid advance of water demineralization technologies, water purification at
the wellhead would need to be tailored to meet the specific characteristics of water production in
each individual well. First, the amount of water at each particular site is limited; by well
production and by available storage capacity and distribution pipelines at the site. The
desalination technology used must be efficient for application in small or medium-scale water
treatment scenarios and insensitive to the variability in water chemistry. Second, formation and
production history will have a dramatic influence on produced water quality and how the
purification technology can be deployed. Finally, any sophisticated pretreatments must be
avoided because they are generally energy-intensive; the novel strategy of produced water
purification must be tolerant of suspensions and floating oil.
The proposed research will overcome these challenges for wellhead deployment. Specific
advantages of the low-temp measures distillation include: (1) built-in water condensers and
deployment of heat pump will enhance latent heat recovery, (2) the project will deploy co-
produced geothermal energy and solar energy sources for driving the water desalination process,
and (3) the process is less affected by water quality and quantity and thus meets the requirement
of wellhead deployment.
B. Problems Addressed in this Research Project
Wellhead produced water desalination is based on a reasonable technology: the
humidification-dehumidification process. The major obstacle to produced water purification is the
required energy intensity and associated high operational cost. It is essential to deploy solar and
co-produced energy sources for water heating, due to their availability and low cost.
Deployment of solar energy faces difficulties, such as seasonal variation in solar radiation
intensity and the need for quite a large amount of land use. Co-produced geothermal energy
varies with geothermal gradient and depth of fluid formation. Thus, integration of the water
separation unit with co-produced energy sources at the wellhead requires consideration of energy
needs and availability at each particular site.
A. Impact on U.S. Domestic Gas Supply
A major part of production in New Mexico is from marginal wells that produce less than
100 bbl/d. Most of these wells are operated below the lower edge of profitability and are
produced and maintained by small operators, who generally do not have the pipeline for water
transportation and facility for disposal. A general process is to transport the produced water by
water truck to the disposal site for treatment; a costly process that can make an otherwise
profitable operation uneconomic. This application of cost-effective technology for produced
water purification at the wellhead will give new life to low-yield producers and a reason to keep
them pumping. Also, many uneconomical producing wells could be profitable if the produced
water becomes an immediate revenue at relatively low cost, such as for drilling fluids or
B. Likely Environmental Impacts
The proposed project targets the difficult problem of produced water purification at the
wellhead for direct disposal or beneficial use. Successful development from this project will
result in a considerable decline in salt water disposal. The waters purified by the proposed process
could be a valuable clean water resource for land revegetation and drilling fluids. In addition, any
reduction in deep well injection will significantly reduce the risk of ground water contamination
from injected produced water.
C. Path to Application
The proposed research includes two phases with research objectives targeting the
development of a cost-effective produced water purification technology and its on-site
demonstration for wellhead application. In Phase I, a low-temperature distillation unit with
desalination will be constructed. Operational parameters will be optimized for energy efficiency
and latent heat recovery. In Phase II, produced water purification will be demonstrated at the
wellhead of Fed 00#3 and Floyd #2, which are operated by Harvard Petroleum Corp. and Robert
L. Bayless, Producer LLC, respectively.
(1) Monthly status reports.
(2) A final report on the results of the defined efforts
(3) NMIMT will build and maintain a web site with information about the project and
updates as appropriate
(4) NMIMT will make a minimum of two presentations in local professional organization
meetings: one each in Permian and San Juan Basin areas.
(5) NMIMT will make one presentation at a RPSEA-directed program level event.
(6) NMIMT will provide an article discussing this project to at least one producer-oriented
(7) NMIMT will provide a technical report detailing results of experimental investigations.
(8) NMIMT will construct a produced water purification unit with a capacity of 30 bbl/day
by the end of year one.
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Water from Production of Crude Oil, Natural Gas, and Coal Bed Methane,” contract no.
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