Long Term Integrity – Well Abandonment (GHG07/51) Risk assessment studies completed so far have all highlighted wells as a high potential risk for seepage Range of wells involved Injection, production abandoned wells Ultimately, all wells will need to be closed so they do not pose a future seepage source Expect injection and production wells to be completed to best practise Studies identify problems with well completions and gas seepage Recognised by Industry as an issue New API code developed

Long Term Integrity – Well Abandonment Abandonment procedures for wells in regions Developed and reinforced over time Likely that the CO 2 plume will spread over are that includes wells completed at different times Abandonment standard of old wells will be to a lower technical standard than newer ones Regions like Texas and Alberta there may be technical issues and significant financial costs involved to remediate all wells before a project starts Need to help guide future practise on well abandonment

Study Aims and Objectives Aim of study is to review well abandonment practises in regions where CCS will be deployed Objective: Highlight areas of concerns over long term integrity in current abandonment practises Help develop new guidelines Identify how best to remediate old abandoned wells

Outline Scope of the Study - 1 Well abandonment status Establish a high level regional data set to allow ease of assessment of issues such as: Good/bad record keep Good/bad abandonment procedures High/low population density Screening tool to highlight regions of concern Review of Abandonment Practise Examine potential problems with long term sealing potential in existing procedures

Outline Scope of the Study - 2 Guidelines/recommended practise for new abandonment practise Issues to consider include: Use of CO 2 resistant cements Plugging only across permeable zones or completely to surface Area of Influence Areal extent of plume in different formations will impact on different numbers of wells Can we develop a risk ranking methodology for wells to assess which to remediate first and those to monitor?

Study Outcomes Recommendations on reinforcement of current regulations on well abandonment Feed into Well bore Integrity network Peer review Will need close co-operation with industry and regulatory bodies to be successful Achieve this through network

Long Term Integrity – Well Abandonment Committee is asked to: Approve proceeding with the study Suggest possible contractors Suggest expert reviewers for the study report Resources: Financial – Average Management – Average