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Well Design Differentiators CO 2 Sequestration in Depleted Reservoirs

Well Design Differentiators CO 2 Sequestration in Depleted Reservoirs. SPE 124274 Presented at Offshore Europe 2009 Conference and Exhibition “Towards a Low Carbon Future”. M. J. Haigh. Introduction. Why is this subject important? Limited CCS well design knowledge available

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Well Design Differentiators CO 2 Sequestration in Depleted Reservoirs

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  1. Well Design DifferentiatorsCO2 Sequestration in Depleted Reservoirs SPE 124274 Presented at Offshore Europe 2009 Conference and Exhibition “Towards a Low Carbon Future” M. J. Haigh

  2. Introduction • Why is this subject important? • Limited CCS well design knowledge available • CCS to play key part in O&G future • Feasibility study • Depleted gas reservoir • Other sources • Specialist service companies

  3. Objectives • Review environment of a CO2 injection well • Identify main well design issues and hazards • Evaluate and assess the impact • Propose potential solutions • Key areas: • Injection Operations • Well Integrity

  4. Project Management • Technical workgroups • Capacity • Integrity • Injectivity • Identified areas of integration • Provided practical project framework

  5. Injection Operations • Challenges during Injection: • Establishing design constraints • Review the effects of low wellhead temperatures • Accurately predicting CO2 phase transition behaviour • Reduced perforating efficiency in depleted reservoirs

  6. Design Constraints • CCS developing concept • New projects will consist of demonstrator schemes • Late life cycle: Full base load injection • Specific project requirements • Initial gaseous ramp up stage • Power generation companies • Project management disconnect • Fit for purpose injection strategyrequired

  7. Low Wellhead Temperatures • Temperature drop across choke • Potential hydrates at tree valves • Integrity issues • Valves • Tubing hanger seals • Dehydrate flow stream • Evaluate risk of hydrate

  8. CO2 Phase Transition Behaviour • Demonstrator scheme • Gas phase injection / liquid phase injection • Gas phase injection • Reservoir pressure increases • THIP increased to maintain injectivity • Critical pressure reached • Liquid phase injection • Reservoir pressure continuesto increase

  9. CO2 Phase Transition Behaviour • Phase transition • Unstable phase behaviour • What we think could happen: • Fluid density increases • Injection rate increases • Depressurisation of wellbore • Mitigation strategy: • Maintain single phase in wellbore • Velocity reducing insert string • Modification of THIP

  10. CO2 Phase Envelope

  11. Injection Strategy

  12. Injection Strategy Benefits • Avoids phase transition uncertainty • Single phase flow in wellbore • Simple architecture • Flexibility from gas to liquid phase injection (stages overlap) • Reduced hydrate risk downhole • Well duty: Injection and observation • Increased sink integrity (less penetrations) • Reduced project CAPEX

  13. Perforating Efficiency • Cased and cemented • Best for long term hydraulic isolation • Reduced perforation efficiency • Conventional static underbalance not possible • Perforating options • Extreme overbalance perforating • Reservoir k > 100 mD • Leak off rate below fracture pressure • Reactive perforating • Suitable for depleted reservoirs

  14. Reactive Perforating Normal crushed zone occurs Exothermic reaction with pressure surge Super-charged pressure surge removing damaged zone Beneficial tip fracture

  15. Material Selection • Metallurgy selection subject to range of views • Tubular materials options • Carbon steel • Glass reinforced epoxy (GRE) lined CS • 13% Cr stainless steel • CRA such as Duplex • Specific corrosion assessment • Water solubility in CO2

  16. Water Solubility in CO2 THIT 43 degF THIP 580 psia CO2 Solubility is 500 ppm Phase Boundary

  17. Well Integrity Workflow Well Characterisation Monitoring Plan Leakage Scenario Workshop Remediation Options Degradation Modelling Risk Assessment

  18. Measurement and Monitoring • In well monitoring • Integrity risks • Wellhead / packer feed through-ports • Fibre optics selected • Increased reliability and performance • Integrity monitoring • DTS • Wellbore temperature correlation • Injection profiling

  19. Summary • Technical workgroups • Capacity, Integrity and Injectivity • Key injectivity challenges • Potential CO2 phase instability • Maintain single phase • Velocity insert string • Reduced perforation efficiency • Reactive perforating • Well integrity • Leakage scenario workshop

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