Storage Development Plan SDP for Abandoning High Risk Development Wells and Drilling Fit-For-Purpose CO2 Injectors Offshore Carbon Capture Storage CCS Project

Abstract

Operators are majorly focusing on zero carbon emission to comply environmental rules and regulations. This paper aims to give insights on world's major CCS project Storage Development Plan (SDP), where CO2 injection wells will be drilled to inject, and store produced CO2 from contaminated fields. To safeguard the CO2 storage containment, the integrity of all wells needs to be scrutinized. Ensuring long-term wells integrity of existing Plug and Abandonment (P&A) and active wells that penetrated the selected CO2 storage reservoir is the key to reduce leakage risks along the wellpath for long-term containment sustainability. Development wells in the identified depleted gas field are more than 30-40 years old and were not designed with any consideration of high CO2 concentration in the reservoir. Possibility of leakage along the wellbores due to accelerated corrosion, channeling, cracks, cannot be ignored and requires careful evaluation. Rigorous process has been adopted in assessing the feasibility for converting existing producers into CO2 injector. Wells disparity between the required defined basis of designs for gas producer and CO2 injection wells governs the re-usability for CO2 injection or needs to be abandoned. New three (3) CO2 injectors with fat to slim design approach, corrosion resistant alloy (CRA) material and CO2 resistant cement are designed in view to achieve lifecycle integrity. Optimum angle of 60deg and maintaining the injection pressure of 50 bar at 90MSCFD rate is required for the injection of supercritical CO2 for 25 years. On top, during well execution, challenges such as anti-collision risk, total loss scenarios while drilling in Carbonate reservoir needs to be mitigated. The completion design is also focusing on having minimal number of completion jewelries to reduce pressure differential & potential leak paths all the way from tubing hangar down to the end of lower completion. Well design optimization from fat to slim has been carried out based on WellCat sensitivity analysis output. Well integrity life cycle monitoring using in country value latest generation fiber optic as well as acquiring seismic for CO2 plume development.