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Published byAugustus Davis Modified over 8 years ago
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GLO Offshore South East Asia Steve ‘Gas Lift’ Gossell – MEA Senior Gas Lift Engineer
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Field Review Offshore 100 – 150 meter water depth Stacked Reservoirs – 1000 ++ ft 7” Cased Hole Depletion Drive small Compartments Some Strong Water Drive “Bottoms Up” Commingled Reservoirs Sandstone Unconsolidated 2000-2500 m (6500-8000 ft) TVD
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Field Review Compressed Gas on 90% of Platforms Gas Volume not Limited Single String Tubing 3 ½” PPO (Fluid Operated) Valves 1.0” Spring Loaded Operating Orifice Valves made from Unloading Valves Step 1 GLO Project
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Objectives Primary: Change PPO to IPO Unloading Valves in 40 wells Increase Oil Production by 10% Teach Process Secondary: Inspect all Valves Pulled Evaluate Gas Lift Design Logic Evaluate Gas Lift Shop & Field Operations/Facilities
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Process Dedicated GLO Slick Line Unit Flowing Gradient Surveys Before & After Change Valves: –Before FGS with Well Test Static Build-up Calibrate Well Model IPR & Match VL Correlation Gas Lift Design & Valve Change –After Repeat FGS with Well Test after 3 days for Stabilization Check Model Inspect Valves Report
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Production Results – 24 Wells
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FGS Examples Compare Before & After Results Compare Pattern of Outflow Performance Note Liquid Rate, Water Cut, & Draw down
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66% Increase
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146% Increase
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520% Increase
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143% Increase
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811% Increase (Realistically 64% based on Avg. Well Test 250 bpd 96% WC)
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Example Well Model Strong Water Drive Note Match from Calibrated Model to 2 nd Well Test
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Load Well Test & Survey Data into Model Not a good match
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Calibrate Model Good Match: Suspect total gas from separator too high, change GOR
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Determine Optimum Injection Rate Nodal result from calibrated model
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Match Inflow/Outflow with Optimum Lift Gas Rate
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Create Gas Lift Design Design for Worst Case Scenario
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2nd Survey, New Design, Check Model 43% Measured Increase in Liquid Rate
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Valve Inspection Results 84 PPO Valves Inspected from 27 Wells 65% with Test Rack Open (Ptro) Set Pressure 10% or more out of Design Range. 26% with Failed Bellows; would not open. 46% with Leak Rates medium to very high. 14% with Leak Rates so high could not measure Ptro. 11% tested OK = only 1 in 9 valves passed inspection. 25 Orifices Inspected: 52% with failed bellows restricting flow.
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Offshore Gas Lift Shop Facility Ptro set with Hydraulic Oil Pump
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Packing Filed Down to Assist Installation 4082’ #3 2967’ #2 1851’ #1
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PPO as Orifice Valve: Remove Ball Bellows failed & extended into Flow Path on 13 of 25 Orifices inspected = 52%.
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PPO as Orifice Valve: Bellows extended onto seat
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SCSSSV: Full Bore Flapper vs. Ball Valve
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Thanks for Listening – Questions or Comments? Steve ‘Gas Lift’ Gossell – MEA Senior Gas Lift Engineer
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