CASE STUDY
Southern Oklahoma
Vapor Tower Replacement
Situation:
A large independent operator was developing deep horizontal
shale wells in southern Oklahoma. The oil produced had a
high API gravity and generated large volumes of flash gas.
The operator’s standard production equipment consisted of a
horizontal three-phase separator operating at approximately
100 psi, a vapor recovery tower with dedicated compression,
and four to eight 500 bbl oil tanks. The tank vapors were
piped over to a flare (see photo below).
shut in the production location. The operator needed a way
to recover gas directly from the tank battery in a way that
eliminated the possibility of oxygen being injected into the
sales line.
Issue:
key. All ERS units all incorporate a patent-pending suction
pressure control system that can be set to keep tank
pressures as low as 0.25-0.50 ounces/in2, without ever
pulling a vacuum on the tank battery.
The vapor recovery tower was designed to remove and
recover the majority of the gas remaining in the oil after
primary separation. However, the high API gravity of the oil
compounded by the finite resonance time within the vapor
tower resulted in large volumes of flash gas continuing to
break out from the oil inside the tank battery – the Vapor
Tower was unable to recover enough flash volume ahead
of the tanks. The tanks were experiencing high pressures
causing the pressure reliefs to vent to atmosphere. The
operator tried to curtail production in order to mitigate these
issues, but even at lower production rates, the tanks were
still seeing excessive pressures and gas being routed to the
flares. The vapor towers simply could not provide adequate
resonance time for flash gas to break out while the oil moved
through them.
The operator recognized that the majority of the flash gas was
breaking out from the oil inside the tank battery due to much
longer resonance times that the tank battery provides. They
re-plumbed the traditional VRUs to pull directly from the tank
battery, but the 3rd-party gas gatherer immediately detected
excess oxygen downstream of the wellsite and threatened to
EcoVapor
Recovery
Systems
Solution:
The operator’s area facilities engineer contacted EcoVapor
Recovery Systems (ERS) and discussed how our systems
would address their issues. Tank pressure management was
Oxygen was also jointly identified as a paramount concern.
To ensure compliance with pipeline specifications, ERS units
also incorporate EcoVapor’s patented oxygen destruction
technology that takes hydrocarbon gas contaminated with
oxygen and reduce the O2 content to 8 ppm or less.
The operator installed one ERS 120 MCFD unit on a test site
where it pulled flash gas directly from the oil storage tanks.
Once the ERS unit was installed, the vapor tower compressor
was shut in and turned off. The ERS unit was able to handle
all the gas flashing off the oil in the tanks, including any gas
that was previously taken off at the vapor tower. Tank
pressures were reduced to < ½ ounce, leaving the flares
dormant. ALL flash gas on location was being recovered
and sold, and the 3rd party gas gatherer immediately
stopped seeing oxygen coming from the test site.
The operator eventually installed eighteen ERS units and
removed every vapor tower compressor from those sites.
Peter Mueller, CEO
[email protected]
www.ecovaporrs.com