Decrease hydrate formation, produced water contamination, and
A gas pipeline in a remote area of Alberta was used to transport
approximately 90,000 ft3/d [2,430 m3/d] of gas across
difficult terrain to a remote amine plant. Produced water was introduced into
the pipeline at various locations throughout the system, with the majority of
produced water entering the pipeline after a compressor station.
The pipeline connecting the compressor station to the gas plant was
treated with 1,057 galUS [4 m3] of methanol to prevent hydrate
formation in the gas pipeline. Although methanol is effective at reducing
hydrates, it contaminates the produced water, increases corrosion risk to the
system, and adds to the operational costs. The customer had previously tried
reducing the volume of methanol entering the pipeline, but this resulted in an
increase in the formation of hydrates.
Eliminate hydrate formation with GT-7569 hydrate inhibitor
To help the customer mitigate hydrate formation, Schlumberger
recommended a hydrate inhibitor program using GT-7569 kinetic hydrate
inhibitor. Initial application of GT-7569 inhibitor commenced at 0.28 galUS/min
[1.5 m3/d], or approximately 40% of the methanol injection rate. The
pipeline from the compressor station to the gas plant was pigged twice a week
and the pig returns checked for the presence of hydrate crystals.
The pressure on the inlet of the gas plant was also monitored because a
pressure decrease was known to indicate hydrate formation. Optimization of the
GT-7569 hydrate inhibitor injection rate continued without hydrate formation.
Analysis of the produced water during the optimization trial confirmed
reduction in contaminant levels.
Resolve concerns of produced water contamination and corrosion
Following approximately 6 days between the first and second pig run,
when no hydrate crystals were found, GT-7569 hydrate inhibitor injection rate
was reduced to 0.18 galUS/min [1 m3/d]. This rate was then
maintained for two pigging cycles (12 days) while the operator monitored the
pig returns and line pressure. After 12 days, the rate was reduced further to
deliver an optimal injection rate that was determined to be 0.13 galUS/min, the
rate at which hydrate formation, inlet pressure reduction at the gas plant, and
produced water contamination were eliminated.
The volume of chemicals required to treat hydrates was reduced by more
than 80% and the contamination of produced water by 100%. Operational costs
were lowered by more than 50%.Operational costs have been reduced by over 50%
since the implementation of the kinetic hydrate inhibitor program.
Contamination of the reflux water has been eliminated and corrosion concerns
associated with methanol carryover into the amine plant have been resolved. The
program has been optimized from an initial injection rate of 1,500 liters per
day to 700 liters per day. The volume of chemical required to prevent hydrates
have been reduced by over 80%.