Well Integrity: Modeling of Thermo-Mechanical Behavior and Gas Migration along Wells-Application to Ketzin Injection Well

Well integrity plays a key role in the overall performance of oil and gas projects, including Carbon Capture and Storage (CCS) projects. Well integrity has to be demonstrated over the well life-cycle, during operations (production, injection and/or monitoring), abandonment and few hundreds of years after closure, particularly to ensure effective CO2 confinement into the reservoir.To contribute to the development of CCS technologies at a commercial scale, a CO2 injection experiment was developed in Ketzin, Germany. The project included drilling three wells: one for CO2 injection, and two for CO2 monitoring. The COSMOS 2 R&D project included wellbore integrity evaluation through extensive modeling at a meso-scale (well components scale) and a macro scale (well scale). The modeling activities focused on the fluids migration from the reservoir along the wellbore taking into account ageing mechanisms (e.g. casing corrosion and cement leaching) and micro-annulus opening at cement/casing/rock interfaces due to thermo-mechanical stresses.Such modeling results have to be integrated in a pro-active risk-based management of well integrity in order to optimize design, define monitoring and maintenance action plan or demonstrate safety to authorities. The benefits are a good knowledge of the risks (causes and impacts), the assurance these are under control and, as a consequence, insurance of a secured investment.