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 Well Integrity Modelling software, STEM-flow, to predict the statistical life of each plug based on material qualification 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 O&G UK 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 plug 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. Astrimar also use the method to support operators developing a justified well integrity management strategy for managing abandoned wells over the long-term.
Leak rates are predicted based on the expected well fluids, fluid composition, well pressures and temperatures, plug and barrier geometry, and plug location. They are also based on plug and casing materials and associated degradation rates, developed from material qualification 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 uncertanties. 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 assist both technology developers and operators in the provision of plug integrity assurance.