Analysis of pressure data:
Fluid types, contacts and distribution.
Presence of reservoir compartmentalisation.
Presence of hydrodynamic flow (i.e. tilted hydrocarbon-water contacts).
Reservoir connectivity.
Identification of suitable storage sites for CO2.
Image showing seismic interpretation of structure and derived map of overpressure compartments with uncertainty.
O’Connor et al., 2013 The determination of seal capacities for highly pressured traps: a “Best-Practice” workflow. In: Proceedings of Indonesia Petroleum Association Conference, Jakarta.
Seal Capacity is critical for:
- Estimation of Column Height.
- Identifying Breached Seals.
- Assessing volumes of CO2 that can be injected.
Image shows inputs to determine seal capacity.
O’Connor et al., 2013 The determination of seal capacities for highly pressured traps: a “Best-Practice” workflow. In: Proceedings of Indonesia Petroleum Association Conference, Jakarta.
Reservoir Stress Path
Understanding reservoir stress state is vital in field development to maintain production targets as well as caprock integrity.
Since the total minimum horizontal stress decreases during depletion, the risk of lost circulation in a depleted reservoir is greater than it was before production started.
Pressure during injection of CO2 cannot exceed the least compressive stress at the base of the caprock at any location.
Image shows the geology of the Lower Kutai Basin, as well as the stress path for depleted reservoirs.
Ramdhan, O’Connor et al, 2022. Pore pressure-minimum horizontal stress coupling estimation in Tunu Field, Lower Kutai Basin, Indonesia, and its implications for reservoir development and CO2 storage.
Pressure effects on seismic response – cross-discipline application of pressure:
- Effects of pressure on AVO response.
- Pressure input into QI modelling (in reservoirs and seal above) to understand fluid content.
- Pressure models to understand lithology and fluids present.
AVO Classes (after Rutherford and Williams, 1989)
Naturally draining reservoirs
Enhance seal capacity in traps allowing longer-than-expected hydrocarbon columns as well as providing migration pathways, possibly into new traps.
Tilted contacts affect trap volumetrics and placement of appraisal and development wells.
Depleted saline aquifers allowing water escape as CO2 is injected.
Image shows saline aquifers depleted naturally over geological time.
Jones, D., O’Connor, S., A. and Swarbrick, R., E. 2008 Where has all the pressure gone? The evidence from pressure reversals and hydrodynamic flow. First Break Volume 26 September