RELIABILITY & OPTIMISATION OF ARTIFICAIAL LIFT SYSTEM RELIABILITY & OPTIMISATION OF ARTIFICAIAL LIFT SYSTEM 21 21 st st October 2005 October 2005 By Dr Sib Akhtar By Dr Sib Akhtar MSE (Consultants) Ltd MSE (Consultants) Ltd Carshalton, Surrey SM5 2HW Carshalton, Surrey SM5 2HW [email protected][email protected]www.mse.co.uk Tel: 020 8773 4500 www.mse.co.uk Tel: 020 8773 4500 Effects of Extended Recycle on Effects of Extended Recycle on Gas Lift Compressors in Mature Gas Lift Compressors in Mature Assets Assets
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RELIABILITY & OPTIMISATION OF ARTIFICAIAL LIFT SYSTEM 21 st October 2005 By Dr Sib Akhtar MSE (Consultants) Ltd Carshalton, Surrey SM5 2HW [email protected].
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RELIABILITY & OPTIMISATION OF ARTIFICAIAL LIFT RELIABILITY & OPTIMISATION OF ARTIFICAIAL LIFT
SYSTEMSYSTEM
2121stst October 2005 October 2005
By Dr Sib AkhtarBy Dr Sib AkhtarMSE (Consultants) LtdMSE (Consultants) Ltd
100,000 bpd capacity using miscible gas injection for enhanced oil recovery
Feasibility of world’s highest pressure gas injection compressors at 710 bar
Design of very high pressure compressors
Vendor design audit
Harweel Gas Injection Compressor StudyHarweel Gas Injection Compressor StudyHarweel Gas Injection Compressor StudyHarweel Gas Injection Compressor Study
Petroleum Development of Oman/ShellPetroleum Development of Oman/ShellPetroleum Development of Oman/ShellPetroleum Development of Oman/Shell
Joint Industry Project (JIP) – Phase IIIJoint Industry Project (JIP) – Phase IIIJoint Industry Project (JIP) – Phase IIIJoint Industry Project (JIP) – Phase III
Five Operating CompaniesFive Operating CompaniesFive Operating CompaniesFive Operating Companies
Visual Representation of Visual Representation of Gas Lift SystemGas Lift SystemVisual Representation of Visual Representation of Gas Lift SystemGas Lift System
Typical Gas Lift Compressor Typical Gas Lift Compressor for Mature Assetsfor Mature AssetsTypical Gas Lift Compressor Typical Gas Lift Compressor for Mature Assetsfor Mature Assets
John Crane have recommended that the seals, especially on the NDE are upgraded to the improved version of the 28AT, the 28XP. Advantages of the 28XP over the current 28AT:
Polymer rings incorporated, increase operating temperature up to 600OF, polymer rings also have a higher resistance to chemical attack
Sliding Carriers, eliminates extrusion gaps through differential thermal expansion
Carbide seats have shrouding to protect seal and shaft in the event of a catastrophic failure
The cost of an upgraded cartridge is approximately £50,000
Gas Seals – Replacement SealGas Seals – Replacement SealGas Seals – Replacement SealGas Seals – Replacement Seal
Protect LP Compressor from Low Molecular weight swing by increasing surge control line
Small loss in head and discharge pressure due to shallow curve
Recommendations - Control System – Recommendations - Control System – LP Surge LineLP Surge LineRecommendations - Control System – Recommendations - Control System – LP Surge LineLP Surge Line
Recommendations - Control System Recommendations - Control System – LP Surge Line– LP Surge LineRecommendations - Control System Recommendations - Control System – LP Surge Line– LP Surge Line
Factors With The Potential To LimitFactors With The Potential To LimitMaximum Production ThroughputMaximum Production ThroughputFactors With The Potential To LimitFactors With The Potential To LimitMaximum Production ThroughputMaximum Production Throughput
Turbine performance
GG compressor, combustor, power turbine
Process gas compressor performance
Head, efficiency
Unwanted recompression of process gas (recycling)
Process and control instabilities
Offshore testing and subsequent analyses identifies capacity limits
GASMAN™ Modelling of Compressor TrainsGASMAN™ Modelling of Compressor TrainsGASMAN™ Modelling of Compressor TrainsGASMAN™ Modelling of Compressor Trains
Compressor Performance LossesCompressor Performance LossesUsing More Realistic ExpectationsUsing More Realistic ExpectationsCompressor Performance LossesCompressor Performance LossesUsing More Realistic ExpectationsUsing More Realistic Expectations
When more realistic performance expectation are used as a datum;
Much of the efficiency “losses” in the three stages can be accounted for
Much of the head “losses” in the 3rd stage can be accounted for
If API datasheets provided are representative of the as-built machines, the head and efficiency profiles generated by the machine in the field are reasonable
Trains A and B are exhibiting reasonable in-service head and efficiency. It is unlikely a replacement machine for the same duty would yield significant increases in gas rates once in service
Train C appears to be exhibiting higher losses in Stage 1, and may benefit from an overhaul
Potential Leakage Paths via KOD CascadesPotential Leakage Paths via KOD CascadesPotential Leakage Paths via KOD CascadesPotential Leakage Paths via KOD Cascades
Cascade Test – Train A Flows At Same PowerCascade Test – Train A Flows At Same PowerCascade Test – Train A Flows At Same PowerCascade Test – Train A Flows At Same Power
Recommend that valve sizes be investigated to more effectively regulate rate of liquid drain and prevent formation of gas leakage path
Two new trains appear to achieve liquid level control effectively – liquid levels maintained at around 15%, thus preventing gas recycle loop and unstable operation
A better understanding of liquid stability and its relation to temperature and pressure would be beneficial
Gas Lift Compression System for mature assets were analysed by testing and careful analysis
Model analysis necessary to verify test performance of gas compressor and drivers
Compressor power and engine power balance achieved
Turbine ISO power of 9.2 MW reduced to 7.6 MW when corrected for high ambient temperature 30 C
Gas path analysis identified additional power losses from bleed valves and Inlet Guide Vanes settings. These losses are fully recovered by maintenance activities