Department · IOGP 510
Subsurface
Scope
Geoscience, reservoir engineering, petrophysics, reserves and resources, subsurface uncertainty, field development planning inputs, and the integrity of the geological and reservoir models that downstream decisions depend on. The function that owns what is in the ground and what we believe it will do.
The reframing
"Subsurface is rarely seen as a management-system function — it tends to live in a parallel world of technical work that informs decisions but is not formally governed. The framework forces honesty: subsurface uncertainty is a risk (Element 5), reserves classification is a standard (Element 2), the geological model is an asset whose integrity must be assured (Element 6), and reserves audits are a third-line assurance act (Element 10)."
Footprint across the framework
E01
Commitment and Accountability
This is where the company commits to how it makes decisions about the subsurface — a domain dominated by uncertainty, where governance discipline is the only meaningful protection.
3 docs →
E02
Policies and Standards
This element holds what good technical work looks like — the standards governing evaluation, classification, peer review and data quality.
7 docs →
E03
Organisation, Resources and Capability
This element holds subsurface capability — organisation, competence, TA, peer review panels and external specialist support.
2 docs →
E04
Stakeholders and Customers
This element holds subsurface interfaces — joint venture governance, regulator reporting, internal interfaces with wells and facilities, and external data providers.
2 docs →
E05
Risk Assessment and Control
This element holds the management of uncertainty — scenario planning, sensitivity analysis, decision-gate risk assessment and the reservoir risk register.
5 docs →
E06
Asset Design and Integrity
This element holds the subsurface systems and models — the technical asset of the subsurface function, where data integrity, model governance and traceability live.
8 docs →
E07
Plans and Procedures
This element holds the subsurface workflows — repeatable processes for studies, FDPs, reserves booking and annual review.
6 docs →
E08
Execution of Activities
This element holds subsurface execution — integrated team working, decision forums and real-time data interpretation in operations.
5 docs →
E09
Monitoring, Reporting and Learning
This element captures how subsurface performance becomes visible — reserves reconciliation, forecast vs actual, model update tracking and benchmarking.
5 docs →
E10
Assurance, Review and Improvement
This element holds independent challenge of subsurface — independent technical reviews, reserves audits, peer review processes and external expert reviews.
5 docs →
Where Subsurface pivots into other departments
→ WellsWell placement, target uncertainty, drilling envelope
→ EngineeringSubsurface inputs to facility design
→ Finance & LegalReserves audit, divestment due diligence
→ Operations & MaintenanceReservoir performance, well surveillance