Eight Important Lessons Learned in Phase 1: 2006-2010
In summary the key learnings from Phase 1 of the In Salah JIP are:
- Secure geological storage is achievable
Over the past five years, the In Salah project has securely stored over 3 million tonnes CO2 in a deep saline formation that has been characterised to oil and gas standards.
- Careful site selection is essential
Careful site selection, characterisation and management are essential requirements for secure CO2 storage and determine the success of the subsequent monitoring programme. It is essential to acquire high-quality baseline data.
- Monitoring techniques must be site specific
The CO2 stored at In Salah has been monitored to assess site-specific leakage risks identified during site selection, development and operation. Technologies for monitoring stored CO2 at one site may not work at all for other sites, so there will not be a "one size fits all" monitoring programme.
- Storage sites share common leak risks
The main leakage risks for most CO2 geological storage sites are governed by:
- a- Legacy well-bore integrity
- b- Cap-rock integrity
- c- CO2 plume migration direction
- Quantified Risk Assessments (QRA) – should inform operations
QRAs should be carried out periodically and used to manage leakage risk by informing operations and monitoring strategies. Several assessment methodologies are available, but there is no regulatory agreement on acceptable levels of risk.
- Injection rates and pressures need ongoing management
CO2 injection rates and pressures need to be linked to geo-mechanical modelling and must be continuously monitored and managed. CO2 plume development is not homogeneous, requiring high-resolution data for reservoir characterization and modelling. Advanced geo-mechanical modelling requires further work - focusing on the coupled effects of fluid-dynamics, rock mechanics, geo-chemistry and temperature.
- Wider scope of datasets needed compared to hydrocarbon developments
CO2 storage projects require the integration of a wider scope of datasets over a greater aerial/vertical extent. The monitoring technologies used can comprise mainly existing standard oilfield techniques and practices, however, specialist technologies and modelling of coupled processes may have valuable, site-specific application. The costs of deploying different technologies can be quantified, but the benefits are less easily quantified. Some low-cost technologies can be very effective.
- Regulatory frameworks need to allow for technology advances
The regulation of CO2 storage projects is immature, but the In Salah CO2 storage project could retrospectively comply with the EU CCS Directive and the requirements of the UNFCCC Clean Development Mechanism. Any regulatory framework for CO2 storage should allow for technology advances during the life-time of the development and not be technology-specific.
Next Steps: JIP Phase 2
Technologies and techniques developed and proven in Phase 1 (for example basic InSAR acquisition and interpretation, Quantified Risk Assessment) have been handed over to the Field Operator for routine deployment.
The next phase of the JIP is now focusing on new, next-generation technologies including:
- Advanced, coupled geo-mechanical modelling of multiphase flow and reactive transport
- Dual porosity/permeability fracture modelling to describe flow in fractured rocks
- Development of innovative forward surface-deformation models matched to coupled hydro-geomechanical models and time lapse seismic data
- Development of a model of three components of deformation to improve temporal resolution of InSAR data and understanding of subsurface CO2 plume migration
- Evaluation of micro-seismic technologies and dedicated caprock data acquisition wells