AbstractAbandoned wellbores may pose an important risk to the integrity of CO2 storage formations that have large numbers of existing wells and that risk needs to be better understood. Field and laboratory studies have shown that well cement can be affected by CO2 at differing levels depending on conditions. However, none of this work has looked at the initial conditions of the well (prior to CO2 exposure). Understanding the initial conditions will be important for ensuring that the potential risk of leakage from the storage formation is acceptable. The collection of baseline wellbore integrity data allows for comparison during a project and will also identify any potentially problematic wells before a leak may occur. New field data from wells must be used to begin to understand if there are field-wide similarities between existing wells and how the similarities may be used to assess field-wide leakage risk. Existing data are not sufficiently focused (multiple wells in the same field) and there has been no satisfactory method of accelerating laboratory experiments to create realistic wellbore leakage conditions.Similarities between wells in the same fields were examined as part of a project to study the baseline condition and leakage risk of existing wells. Five wells were analyzed. The wells were split between two fields in the state of Wyoming, USA. The investigation used a combination of wellbore logging and sampling tools to analyze well conditions. Logging tools were selected to provide the maximum information on the materials that were used to construct wells and provide zonal isolation. The logging suite included sonic mapping tools, ultrasonic mapping tools, dynamic testers, and sidewall coring tools. Initial results show that there are similarities between wells within the same fields.