Geomechanical Assessment of Leakage through Oil Wellbores

  • Author / Creator
    Alsayed, Ahmad Nabih A.
  • Carbon capture and storage (CCS) is an approach to reduce carbon dioxide (CO2) emissions. The approach involves three main steps; capturing, transporting, and storing of CO2. Storing is done by injecting CO2 directly into underground deep geological formations such as depleted oil and gas reservoirs, un-minable coal seams, saline formations, and declining oil and gas reservoirs. Safe storage of CO2 into oil and gas reservoirs depends mainly on the caprock sealing that provide a physical natural barrier for leakage to the surface and/or a strata where other energy, mineral and/or groundwater resources are present. Storage integrity assurance is controlled by two mechanisms; geological leakage mechanism and wellbore leakage mechanism. In all problems, dealing with CCS, safety assessment of wellbore integrity is a major challenge. Researchers’ main objective is to gain more information and knowledge to understand wellbore behavior under different states and/or conditions. However, all of these efforts are scattered and dispersed due to either the various approaches of the study and the multi-disciplinary nature of the problem. There is no unified and universally accepted procedure to investigate wellbore leakage mechanism. There is a need for a methodology to standardize the assessment of wellbore integrity in a more regulatory manner. To be a standard code of practice, key elements of the methodology must be gathered, recognized, classified, and systematically ordered. Such considerations necessitate an appropriate procedure that can be standardized and considered as a sound practical tool to check the safety evaluation of wellbores with respect to wellbore leakage mechanism. Wellbore sealing efficiency index is introduced to assess wellbore leakage mechanism with engineering rigor. It can be used as a quantification index to assess wellbore leakage failure mechanism. The index is proposed to be a criterion to rank different wellbore elements in the same formation, to compare with different elements within the same wellbore, and/or to check the safety condition of wellbore. Two indices, storage index and permeability index, are found to govern wellbore leakage mechanism and facilitate the creation of wellbore performance charts that monitor and check wellbores’ leakage mechanism and their lifecycle performance.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Civil and Environmental Engineering
  • Specialization
    • Geotechnical Engineering
  • Supervisor / co-supervisor and their department(s)
    • Chalaturnyk, Rick (Civil and Environmental Engineering, University of Alberta)
  • Examining committee members and their departments
    • Kumar, Aloke (Mechanical Engineering, University of Alberta)
    • Hendry, Michael (Civil and Environmental Engineering, University of Alberta)
    • Schmitt, Doug (Physics, University of Alberta)
    • Sego, David (Civil and Environmental Engineering, University of Alberta)
    • Nygaard, Runar (Petroleum Engineering, Missouri University of Science and Technology)