Assurance of plug integrity can be a challenge whether deploying traditional cement plugs in complex well geologies, or qualifying novel P&A materials and technologies. Astrimar has developed a Predictive Risk-Based Well Integrity Modelling software, STEM-flow, to predict the statistical life of each plug based on material test data combined with well specific data.
Well plugging and abandonment (P&A) poses significant long term risks for the industry, with Operators typically following a prescribed P&A approach in order to meet regulatory requirements. A risk-based approach allows for bespoke abandonment strategies for individual wells, reducing the time and effort needed for low-risk wells, while releasing additional P&A resources for managing higher risk wells. In addition, where it is necessary (according to OGUK guidelines) to demonstrate long term durability for new plugging materials, advanced computational risk-based and predictive well integrity models are required to provide supporting evidence.
Astrimar’s STEM-flow, predictive well integrity model provides advanced modelling and data analysis to support well risk assessment and barrier reliability assurance. Its novel approach accounts for all potential leak paths including through the plug, through casing and rock formation interfaces, and within the casing cement.
Predictions are based on the expected well fluids, fluid composition, well pressures and temperatures, plug and barrier geometry, and plug location. They also reflect plug and casing materials and associated degradation rates, developed from materials test data.
A number of plugs can be incorporated into the well system model which can provide probabilistic outputs for individual plug leak rates, plug life, fluid release over time, and the time for well leakage to exceed an acceptable level.
For some applications with limited data, STEM-flow uses public domain data, with associated uncertainties. These baseline predictions can then be updated with application specific data when available. Potential data sources include plug qualification / verification test results, well condition data and post abandonment inspection data.
Astrimar is able to use STEM-flow software to support both operators designing well P&A solutions using conventional materials and technology developers qualifying new P&A materials. It can also be used to support operators in developing a justified well integrity management strategy for managing abandoned wells over the long-term and for CCUS applications.