Caisson Integrity Analytics for Australian Operator

Project outline 

Imrandd recently completed a data analytics and integrity assessment scope for a leading Australian upstream operator. The project focused on a caisson on an offshore asset, resulting in significantly more accurate remaining life estimates than those provided by traditional methods.  This contract was achieved in collaboration with AISUS, who specialise in offshore inspection services using advanced inspection technology.

The Imrandd team used its propriety technologies to collate and condition data sets from two existing ultrasonic corrosion mapping inspections conducted several years apart. Rather than using the conventional industry approach where uniform corrosion rates are assumed, Imrandd utilised advanced corrosion growth models that account for changes in both corrosion extent and depth, with statistical analysis of the thickness variations between inspections providing the basis for more representative future condition estimates. 

The Solution 

Imrandd’s team of engineers and data scientists executed a structured analytics process designed to extract maximum value from the inspection data: 

Data conditioning 

• Removed spurious readings and corrected systematic measurement issues. 

• Aligned data from both inspections to enable spatial comparison. 

Statistical analysis 

• Quantified localised changes in wall thickness over time. 

• Analysed both depth and area progression of corrosion. 

Corrosion growth modelling 

• Developed a probabilistic model using distributions of wall loss, rather than uniform corrosion rates. 

• Included modelling of expanding corrosion zones (area growth), not just deepening. 

Projection of future condition 

• Generated future thickness maps for use in FEM and section-based structural analysis. 

Result 

The analysis provided a significantly more realistic estimate of the caisson’s remaining life. The operator was able to defer a planned replacement, avoiding a costly and complex intervention. The findings supported a data-backed decision to maintain the caisson in service safely through to the facility’s end of life, optimising both integrity management and operational expenditure. 

• Corrosion was found to be progressing in a localised and predictable manner. 

• Future condition estimates showed no integrity risk within the remaining life of the asset. 

• The caisson’s structural performance was confirmed to meet requirements without immediate intervention. 

Impact / Benefit 

• Avoided major replacement: The analysis justified cancelling a planned, high-cost caisson replacement project. 

• Cost savings: Enabled reallocation of capital to other priority areas. 

• Improved confidence: Provided the operator with a defensible, data-driven integrity assessment. 

• Asset life extension: Validated safe operation of the caisson through to the end of field life.