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Late
in 1999, BP America initiated a study with us to assess the
viability of applying expert system technology to improve gas
production within its North American gas assets. Pilot fields
were selected in Oklahoma and East Texas.
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| The
Project Challenge |
The
focus of the study was to assess the potential production gains resulting
from the application of expert system technology to gas well deliquification.
Solutions developed during this project required an existing base
of field automation comprised of intelligent wellhead controllers
communicating with a central host system. The expert system was then
applied as an additional layer of intelligence on to the existing
automation infrastructure.
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For
wells producing volumes less than 100 mcfd, the accumulation of even small
quantities of produced water or condensate in the downhole wellbore seriously
constrains gas production. Production losses are minimized and workover
costs reduced by early detection of adverse operating conditions. A cost-benefit
analysis set a target of 2% to 3% increase in gas production.
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The
Solution |
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MaxGas™
Expert is an application that uses Gensym’s G2 real-time expert system software
engine to build a multi-variable, fuzzy-logic controller linked to the field
automation systems. MaxGas™ Expert encapsulates the expertise of BP production
engineers and field operators in the form of expert system rules. With this
domain expertise, MaxGas™ Expert analyzes incoming sensor measurements from
wells and initiates appropriate responses to changing operating conditions.
The intelligent alarming functionality in the system includes alarms for
various well loading conditions, worn plunger detection, compressor station
performance, and gas production anomalies. The system provides closed-loop
control of plunger lift, intermitters, and switching valve wells that adjust
wellhead control setpoints to maximize gas production.
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The
Process |
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Our
personnel worked with BP’s operations personnel to capture knowledge
regarding the conditions that must exist to constitute an alarm. Further
discussion with operations personnel and analysis of well data was
used to determine the inputs for the controllers. BP identified two
areas in which to focus initial development: intelligent alarming
and gas production optimization.
Intelligent alarming identifies problems and recommends corrective action.
Typical alarms include:
·• continuous comparisons of a well’s production with its expected
decline curve to advise of any anomalies
• worn plunger detection
• tubing leak detection
• adverse operating conditions at well or meter compressor station
performance analysis
Gas production optimization provides continuous adjustment of two set points
to assist operations staff in achieving optimal production rates.
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A 3% production increase
was achieved using MaxGas™ Expert at the East Texas pilot field.
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Project
Benefits |
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The MaxGas™
Expert pilot fields on plunger lift control experienced average production
increases of 3% to 5%. Additional BP pilots have been installed at Anadarko,
Texas, and several Canadian assets. The upside potential for this technology
includes the majority of the 2900 plunger-lifted wells that BP operates
in North America.
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Intangible
benefits of this project included reduced gas venting, increased effectiveness
of manpower with an estimated 10% in time savings, and shared best-plunger-lift
practices across the company. |
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The economic
and operational success of MaxGas™ Expert proves that expert systems technology
make significant contributions to profitability and efficiency in field
production operations.
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