American Oil and Gas Reporter - June 2017 - 48

FIGURE 2
Electromagnetic Flowmeter
Installed On Evaporator System

gases in direct contact with the produced
water in order to evaporate the highTDS, salty liquid into clean water vapor.
The result of this process is a dry
solids cake that is deposited in a roll-off
container, and then recycled, placed in a
landfill, or used for commercial applications
such as road salt or feedstock (Figure 1).
Unlike traditional wastewater management techniques, submerged combustion evaporation can be performed directly
at the producing field. This eliminates
the need for tanker trucks to remove
liquid waste from the well site for injection
into a disposal well. The amount of dry
solids cake produced by evaporation is
much smaller than the volume of produced
water that would otherwise require disposal.

Flow Measurement
During the operation of a produced
water evaporator, the volume of highTDS water entering the system is metered,
followed by a measurement of the amount
of salt crystals or concentrated water exiting the unit. The delta of these two
measurements then is used to calculate
the evaporation total, which is the basis
for a per-barrel service charge billed to
the field operator (Figure 2).
In addition, a programmable logic
controller can employ flow measurement
information to automate the evaporation
process and present relevant information
on a human-machine interface. This solution allows for remote operation without
the need for a full-time operator.
Initially, submerged combustion heating evaporators for high-total dissolved
solids applications were employed using
48 THE AMERICAN OIL & GAS REPORTER

different types of flow measurement technologies. However, unacceptable performance was experienced with both ultrasonic and turbine-type meters.
Ultrasonic metering accuracy was difficult to maintain in the submerged combustion heating evaporator environment.
Positioning and adjusting of the sensors
was frequent, and the accuracy of data
generated was always in question. Turbine
meters were very accurate, but did not
function well because of fouling. The
meters became plugged or occluded with
debris on a continual basis, and disassembly and cleaning required isolating
the units from the storage tanks.
Ultimately, an electromagnetic flowmeter design was selected for the water
evaporator system. This measurement
technique eliminates the need for moving
parts, which can lead to performance and
maintenance issues when used in fluids
containing high solids content. Electromagnetic flowmeters measure virtually
any conductive fluid or slurry, including
process water and wastewater. They are
known for low pressure drop, high accuracy, extended turndown and excellent
repeatability.
The electromagnetic flowmeter used
in the first evaporator system is designed
to achieve ±0.25 percent accuracy. Its
nonintrusive, completely open flow tube
design virtually eliminates pressure loss.
The meter is relatively unaffected by viscosity, temperature and pressure when
correctly specified.
In the first field application, a oneinch electromagnetic flowmeter was installed on the evaporator feed line coming
from the storage tank to replace a turbine
meter. Once the communications were
determined, the electromagnetic meter
was brought online and performed flawlessly. A three-inch electromagnetic
flowmeter subsequently was installed on
the discharge line of the evaporator to
replace an ultrasonic meter. Both instruments have been running for more than a
year without any problems, leading the
manufacturer to design another 1,000
barrel/day unit that will use four-inch
electromagnetic meters on all liquid measuring points.
As in other exploration and production
processes in which the flow of liquids or
gases must be measured accurately during
every phase of operation, reliable flow
measurement is key for submerged combustion heating evaporator technology.
The electromagnetic meters provide precise data on the amount of produced
water entering and exiting the evaporator
system, and enable secure remote operation
to simplify site personnel training and
reducing overhead costs. Additionally,

improved reliability, increased robustness
and reduced maintenance requirements
are achieved by deploying electromagnetic
meter technology.

Benefits To Producers
A submerged combustion evaporator
can help oil and gas companies reduce
operational headaches by evaporating up
to 95 percent of produced water. A true
on-site evaporator represents a desirable
alternative to hauling large amounts of
produced water off site for treatment and
disposal, and can augment on-site treating
and recycling strategies. The specific operational, environmental and business
benefits of this solution include:
* Fewer logistics for handling produced water;
* Reduced truck traffic to minimize
site damage, liability and emissions;
* Less dependence on water haulers
to eliminate scheduling delays and fees;
* Reduced flaring and less likelihood
of spills or surface water contamination;
and
* Reduced injection in disposal wells.
User experience has shown that submerged combustion evaporators that produce a dry solids cake or liquid concentrate
byproduct reduce the costs associated
with wastewater volume reduction by as
much as 50 percent.
Oil and gas operators utilizing a submerged combustion evaporator can expect
ongoing annual savings for the life of
the well because of greater predictability
and control of disposal costs. They also
will have fewer regulatory and operational
issues while avoiding unnecessary risks.
Environmental benefits include a reduced
carbon footprint from trucking and less
stress on local infrastructure.
r

LARRY
JOHNSON

Larry Johnson is a Badger Meter
strategic account manager in Houston. Prior to joining the company in
2015, he served in sales and management positions at Petrosmith, Turbines Inc. and Kimray Inc. He holds
a business administration and management degree from Louisiana State
University-Eunice.

American Oil and Gas Reporter - June 2017

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