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MSE
Case Studies: Dynamic Simulation
The following projects are examples of how MSE has taken a lead role in the selection of machinery, process systems design and the resolution of operating problems by utilising our dynamic simulation software:
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Shell/Pelican
Cormorant Alpha |
MSE was involved in the selection and application of the centrifugal compressor trains, process control system and start-up procedure of this project. This resulted in one motor-driven three-stage centrifugal compressor and a booster-reciprocating compressor being replaced by two existing reciprocating compressor trains.
We were also responsible for carrying out a comprehensive dynamic simulation of the associated gas, centrifugal compressor, gas lift and export, flare and fuel gas systems.
Additional to this, MSE modelled the transient response of the reciprocating compressor train.
After the successful commissioning of the project the system is handling much greater volumes of gas and liquids than originally expected.
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PDO - Saih
Rawl |
The operation of the Saih Rawl Compressor Station has suffered from persistent problems associated with compressor failures and process instability leading to frequent plant shut down and deferment of oil production.
A dynamic simulation model of Saih Rawl plant was developed by us to investigate the transient response of flow disturbances at the plant to assess their effect on process stability and machinery performance.
The study revealed that the compressor was operating at the maximum power limit of the electric motor and power demand could exceed the available motor power during transients. If also found that the existing control system was totally inadequate to handle flow transients encountered and could not achieve process stability.
The
study identified the following:
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The HP/Export compressor K-1120 failed on overload during the day and surged during the night
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The present electric motor driving K-1120 had insufficient power margins and the unit was operating at the limit of its design capability
The report recommended that the present control philosophy should be modified so that the master control system controls the fast acting devices only, i.e. flare control valves and the station control.
The long-term solution of the Saih Rawl Compressors Station necessitated greater installed power. However, this was too costly and could not be justified.
Therefore, MSE developed an alternative cost effective control system, which provided process stability and minimised flaring. We tested alternative set points for separator pressure controllers and optimised the operating conditions, which minimised surging while staying within motor maximum power.
The new control system was implemented during field trials (which were supervised by MSE) and resolved the process instability problem and surging of compressors. The plant has now improved its reliability and availability dramatically since the installation of the new control system.
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Shell UK - Leman AK and BK Compression System |
Shell
was experiencing severe operating problems with multiple compressor trains, including surging and frequent shut down from a variety of machinery and control related problems.
MSE was invited to carry out a screening study of the operating problems. An initial assessment of the compression system was carried out from the plant design data (PFD, P&IDs and heat and material balances), operating data (station flows, pressures and machinery operating conditions) and machinery performance (compressors, drivers, coolers, etc). Based on the results of this assessment,
we formulated reasons for operating difficulties.
MSE then visited the site to collect further information and the results of the analysis were submitted to Shell in a Screening Study Report. The report identified reasons for operating difficulties and provided tentative procedures for improving system operation. We advised the need to collect true performance data of the centrifugal compressors, which are necessary to obtain reliable information from the computer models.
We subsequently built the computer models that highlighted the problem and identified a series of options from which the most cost-effective and practical solution was selected. This model helped Shell identify that the entire production could potentially be handled by one platform (AK) instead of splitting it on two platforms.
By designing and reconfiguring compressor trains using the computer simulation, MSE demonstrated that the entire production of the Leman field could be handled by one platform (AK) and the second identical platform (BK) could be shutdown and decommissioned, leading to a potential saving of $20 million per annum.
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Shell - North Cormorant Compression System |
MSE was invited by Shell to examine the North Cormorant Compression System for oil/gas separation and export. This system was experiencing many difficult operating problems, including surging of machines, high vibrations, high discharge temperatures, fouling of compressors and inability to meet the required discharge pressures. Prior to MSE being invited, compressor manufacturers and other specialists were invited to visit the facility and resolve the problem. New compressor casings were installed but the problems persisted.
We carried out a screening study and analysed the compression system in detail. This process highlighted the potential problem areas. As a result, a list of actions was carried out which stabilised the problems and increased compressor availability. Subsequently, MSE constructed a computer model of the compression facility that was verified with test data to provide accurate forecasting of the facility operations.
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North
Morecome Gas Terminal |
MSE carried out a study for two four-stage reciprocating compressor trains driven by gas engines, rated at 5,000 hp each. We developed the dynamic simulation model for the machines and successfully performed a detailed control and operability study for the two product compressors, which are part of a nitrogen re-injection unit.
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Amoco/CATS
- North Everest (Gas Condensate) |
MSE initially carried out a dynamic simulation of the North Everest and Lomond Platform early in 1991. Later, the North Everest Platform was modified and an injection compressor train was installed to maintain peak condensate production during low seasonal export gas demand.
We developed a dynamic simulation model of the process/compression system, comprising:
This model was used to evaluate the following:
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Balancing
export/import injection rates
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Investigation
of transients associated with export system
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Resolution
of transient problems
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Resizing
of surge control system
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Optimisation
and tuning of controllers
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| For
more details on how MSE can maximise your oil and gas
capital equipment through dynamic simulation, please contact us on +44
(0)20 8773 4500 or info@mse.co.uk.
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