American Oil and Gas Reporter - October 2016 - 79

SpecialReport: Natural Gas Update
If field pressure was to rise and the
load step was not adjusted manually, the
suction control valve would throttle back
automatically to keep the unit from shutting down on overload or differential
pressure. This automated one portion of
the recommendations and left only manual
adjustment of the VVCPs to meet the
utilization target.
Increased Throughput
Once the associated issues were resolved and automatic load control through
suction control was incorporated, implementing the optimization tool moved
quickly from station to station. The immediate gains in station throughput were
significant, with a 10-15 percent increase
seen immediately following implementation of 3606 packages at each location.
Once the optimization tool was configured for the majority of Wattenberg
compressors, operations settled into a
procedure to maintain the increased
throughput. The tool runs every 15 minutes, providing the recommended load
step and additional data. Manual VVCP
adjustments typically are made only when
there is a significant change in field conditions.
Changes to load step range from every
few days to weeks, depending on field
pressure dynamics. Figure 5 shows the
recommended load step from the utilization tool, current load step, unit suction
pressure, and field pressure to illustrate

the actual changes made on an example
unit.
While the gains in throughput on existing compressors did offset some need
for additional compression, saving
Anadarko significant capital expenditures,
new compression also was being installed
while the existing fleet was being optimized. The total Wattenberg gathering
system throughput through February 2016
is shown in Figure 6, along with the
nominal throughput gains from new compression. The approximate throughput
gain from the optimization tool is 80
MMcf/d (10 percent) for the total 3606
fleet. The utilization of Wattenberg 3606
compressors increased from approximately
80 to 95 percent.
Several side benefits from using the
tool have been realized as well. By closely
monitoring various parameters presented
on the CygNet screen, operations has
learned to identify when mechanical
issues are occurring. The engine drivers
are tuned more precisely and reliability
has improved. Correcting PLC errors and
setting other shutdown levels more appropriately has reduced nuisance shutdowns.
Surveying the compressors and building
the equipment databases for accurately
constructing the models have proven
useful for many other applications by
engineering, health and safety, operations,
maintenance, and other departments. The
accurate models created for each com-

FIGURE 6
Wattenberg System Throughput
With Compression Addition and Optimization
Tri-Town "30MM" new compression
5/21/15

St. Vrain "30MM" new compression
4/17/15

Plant Outage

Gas Curtailment (Modulation)

~80 MMcf/d Increase

Tri-Town "30MM" new compression
4/2/15
St. Vrain "30MM" new compression
1/29/15

Mead "30MM" new compression
4/30/15

6
01
8/2
2/1

15
12

/30

/20

15
/20
/10

5
01
1/2

Total System Throughput (3-day avg.)
11

Nominal Throughput for Compression

9/2

15
/20

5
01
3/2

8/2

Current Fleet Throughput

6/1

5
01
4/2
4/2

15
/20
3/5

5
01
4/2
1/1

/25

/20

Mead "30MM" new compression
3/23/15

pressor also are used extensively for
system design and operations purposes.
The optimization tool is being applied
to other gathering assets in Anadarko's
portfolio. Enhancements are being evaluated, and include accuracy improvements
and additional calculations to monitor
operating expense. The methods and procedures employed for the tool also are
being looked at to create variations for
compressor and driver reliability monitoring and predictive maintenance. r

GARY BOURN is a senior staff facilities engineer for Anadarko Petroleum Corporation's midstream operations services and gas plant engineering group in Denver, supporting
compression design and operations
for the company's onshore field developments. He began his career in
research and development at Southwest
Research Institute, working up to a
principal research engineer after 13
years in the natural gas and large engine development group. Bourn then
served as a principal reliability engineer at El Paso Corp. and as a compressor engineer at Kinder Morgan
before joining Anadarko in 2013. He
holds a B.S. in mechanical engineering
from Texas Tech University.
MIKE SUTTON is a senior facilities
engineer for Anadarko Petroleum's
gas plant engineering group in Denver,
working in the Denver-Julesburg Basin.
His responsibilities include compressor
station optimization, compressor operations support, and in-house gas
plant engineering to support operations,
construction and design at Anadarko's
processing complex in Fort Lupton,
Co. Sutton started his career working
for five years with Anadarko's production team in the Powder River
Basin in Wyoming, with the majority
of his work focused on electrical design
and construction. He holds a B.S. in
mechanical engineering and an M.S.
in environmental engineering from
Montana State University.
OCTOBER 2016 79

American Oil and Gas Reporter - October 2016

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