GLO Offshore South East Asia Steve ‘Gas Lift’ Gossell – MEA Senior Gas Lift Engineer
Field Review Offshore 100 – 150 meter water depth Stacked Reservoirs – ft 7” Cased Hole Depletion Drive small Compartments Some Strong Water Drive “Bottoms Up” Commingled Reservoirs Sandstone Unconsolidated m ( ft) TVD
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
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
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
Production Results – 24 Wells
FGS Examples Compare Before & After Results Compare Pattern of Outflow Performance Note Liquid Rate, Water Cut, & Draw down
66% Increase
146% Increase
520% Increase
143% Increase
811% Increase (Realistically 64% based on Avg. Well Test 250 bpd 96% WC)
Example Well Model Strong Water Drive Note Match from Calibrated Model to 2 nd Well Test
Load Well Test & Survey Data into Model Not a good match
Calibrate Model Good Match: Suspect total gas from separator too high, change GOR
Determine Optimum Injection Rate Nodal result from calibrated model
Match Inflow/Outflow with Optimum Lift Gas Rate
Create Gas Lift Design Design for Worst Case Scenario
2nd Survey, New Design, Check Model 43% Measured Increase in Liquid Rate
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.
Offshore Gas Lift Shop Facility Ptro set with Hydraulic Oil Pump
Packing Filed Down to Assist Installation 4082’ #3 2967’ #2 1851’ #1
PPO as Orifice Valve: Remove Ball Bellows failed & extended into Flow Path on 13 of 25 Orifices inspected = 52%.
PPO as Orifice Valve: Bellows extended onto seat
SCSSSV: Full Bore Flapper vs. Ball Valve
Thanks for Listening – Questions or Comments? Steve ‘Gas Lift’ Gossell – MEA Senior Gas Lift Engineer