case study: decommissioning emissions
Unnecessary emissions means unnecessary costs - unlocking the carbon impact of decommissioning is key to minimising costs and optimising efficiency.
at a glance
challenges
complexity
Capturing the complex decommissioning processes through identification of multiple emissions sources and allowing for optionality in developing different scenarios.
data gaps
Limited availability of specific emissions data for certain decommissioning activities necessitating the use of estimations and assumptions.
outcomes
clarity
Detailed but user-friendly Excel-based tool guiding the user to input key data and criteria for fast automated calculation of GHG emissions.
relevant and adaptable
Linkage to partner’s projects to allow integration of complex calculations for activities such as changing power requirements and flushing volumes.
easily communicated
Output dashboard with summary tables and graphs breaking down results by asset and emissions source.
For North Sea operators, decommissioning isn’t just a technical challenge—it’s a financial one, where high emissions directly drive up costs through excess fuel use and operational inefficiencies, impacting tax liabilities and potentially resulting in regulatory delays.
Without a clear understanding of where emissions are coming from, companies risk inflated budgets, approval setbacks, and missed opportunities to optimise their strategies.
Working with Apollo at the request of a major North Sea operator, we developed an emissions forecasting tool that helps operators not only quantify their carbon footprint but optimise strategies that balance environmental responsibility with commercial performance.
Understanding your emissions isn’t just good for compliance - it’s good for the bottom line.
objectives
A major oil and gas operator in the North Sea region sought to have a tool for in-house use to assess greenhouse gas (GHG) emissions associated with decommissioning of offshore platform and subsea assets.
They needed to quantify emissions from Cessation of Production (COP) and well plug and abandonment (P&A) through to topside removal, according to the OEUK Work Breakdown Structure (WBS). A key need was to enable analysis of multiple scenarios to explore the impact of different decommissioning strategies such as timing, P&A strategy and fuel types on emissions.
steps taken
stakeholder engagement
Collaborated with multidisciplinary teams to gather comprehensive data on in-scope decommissioning activities.
data collection and validation
Compiled data from decommissioning activities, including power requirements, fuel consumption, rig and support vessel requirements, well P&A activities, flushing requirements, and equipment usage. Developed basis for decommissioning, clearly defining the scope of the activities.
tool development for emissions calculation
Developed a user input interface for all in-scope emissions sources and activities, broken down by OEUK WBS. Utilised the Greenhouse Gas Protocol for automatic calculation of Scope 1 and Scope 3 emissions by asset and source, applying relevant emissions factors to each activity.
dashboard for communication & integration
Developed dashboard with summary tables and graphs to enable easy integration of results into internal company reporting and planning systems.
documentation of base case
Developed base case scenario based on current decommissioning planning using the tool and provided summary report of the forecast emissions.
results
comprehensive emissions inventory
Delivered a detailed breakdown of GHG emissions for each decommissioning phase, offering a clear understanding of the project's environmental impact.
informed decision-making
Optionality for inputting activity data enables scenario analysis for evaluating the emissions implications of various strategies.
supporting approvals and compliance
When integrated with other decommissioning work streams, this will facilitate internal and regulatory approvals, compliance with environmental regulations and help to demonstrate a commitment to reducing impacts of offshore decommissioning.