The fate of the 27 oil rigs off the coast of Southern California was becoming quite controversial.  The original leases to the oil companies required them to remove the entire platforms at the end of their productive life.  That would be very expensive and it turns out that the the platforms have attracted marine life and support their own ecosystems. Should we remove them, which is very expensive, convert them to artificial reefs to support the marine life, or use them as platforms for wind turbines? An interdisciplinary team created a decision tool in Analytica to explore the costs and benefits and assist the California Ocean Science Trust (OST).  The result was a win-win solution that satisfies almost all parties. 

The Challenge

Leases require that California's 27 offshore oil and gas platforms be dismantled and removed at the end of their productive lives by the oil companies who own them. The two main decommissioning options examined are complete removal and conversion to an artificial reef.  These options have different impacts on cost,  the diverse marine fauna  and air and water quality, and socioeconomics. The decision process involves making choices amongst these multiple attributes,  of which some are quantifiable, and others are not. OST needed an integrated framework to compare and evaluate the decision options against the full range of issues.

Why Analytica?

The project team needed a modeling platform to represent the integrated framework. They considered excel spreadsheets and a more conventional narrative policy analysis, but eventually chose Analytica. “Analytica provided an integrated environment that enabled us to build from initial conceptual models to progressively more complex numerical and narrative models in a transparent and easy-to-use environment.” said Brock Bernstein, Project Manager. “From my perspective, Analytica offered an efficient and effective framework for building a complex multifaceted model using conventional excel spreadsheet data inputs. It offers users the flexibility to easily introduce both quantitative and qualitative scenario options that enables the user to very simply investigate a plethora of alternative results.” remarked Andy Bressler, the Operations & Engineering expert on the team.

The Solution

The PLATFORM Oil & Gas Platform Decommissioning Decision Support Tool is a multi-attribute decision analysis framework to enable decision makers and stakeholders to choose among viable decommissioning alternatives. The framework applies utility theory in giving the decision makers the ability to quantify the desirability of certain alternatives. It allows the decision maker to determine the best options for decommissioning platforms individually or as a group. It takes as inputs the user-selected decommissioning option for each platform, platform-specific decisions about reef enhancements, shell mound removal and the use of explosives, as well as quantified inputs such as decommissioning costs and biomass estimates of marine species. Platform also supports the ability to assign relative values to qualitative attributes, so that they can be included in the quantitative multi-attribute scoring of decision options. The model is highly interactive and supports rapid changes to key assumptions to explore their effects on key outputs. It supports sensitivity analysis to compare the effects of alternative assumptions, including tornado diagrams to compare the effects of changes to key inputs.

Custom Analytica interface for the PLATFORM decision support tool


PLATFORM offers a range of outputs to evaluate results, including the total decommissioning cost by platform, avoided costs based on decommissioning alternative selected, and a multi-attribute score for each alternative.

PLATFORM's tornado sensitivity analysis graph.

The model is set up to be completely transparent, thereby giving users the ability to browse the underlying details, explore assumptions and look at key calculations.


PLATFORM's underlying model is transparent and intuitive

PLATFORM includes a detailed project cost analysis, which amongst several key results offers the user the ability to compute the overall decommissioning costs of selected platforms and scenarios with uncertainty.

Platform probability
Cumulative probability of decommissioning cost for selected platforms

The PLATFORM model was published as an open-source policy model and can be downloaded from the California OST website, along with a copy of the published report and model user guide.


Dr. Brock Bernstein, Independent Consultant with expertise in marine biology, GIS and mapping.

Other supporting authors include Mr. Andy Bressler , Dr. Daniel Pondella, Dr. Astrid Scholz, Dr. Sarah Kruse, Dr. Max Henrion, Mr. Ian Setnicka and Mr. Surya Swamy.

For more...

This project was sponsored by the California Ocean Sciences Trust (OST). The main project webpage offers the ability to download a copy of the open-source PLATFORM model, along with a copy of the model user guide and final report. You can open and run the model with Analytica, including the free Player or Trial.