TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractA number of serious well failures in recent years led to investigations of well integrity issues. The Petroleum Safety Authority Norway (PSA) performed a "pilot well integrity survey" based on supervisory audits and requested input from 7 operating companies, 12 pre-selected offshore facilities and 406 wells. The wells were a representative selection of production and injection wells with variation both in age and development categories.The pilot project indicates that 18% of the wells in the survey have integrity failure, issue or uncertainties and 7 % of these are shut in because of well integrity issues. The selection of wells and the companies indicate that the statistics is representative.The well incidents in the past and the results of "pilot well integrity survey" revealed that the industry needs to increase focus on the barrier philosophy. Control of barrier status is an important SHE factor to avoid major incidents caused by e.g. unintentional leaks and well control situations. Knowledge of well integrity status at all times enables the companies to take the right actions in a proactive manner and thereby prevent incidents.The paper presents the results and the conclusions from the pilot survey. In addition a number of technical well failures will be presented, identifying critical elements such as corrosion, leaks and operational factors. In particular, the understanding of barrier regulations, standards and implementation was found inadequate.

Summary A number of serious well failures in recent years led to investigations of well-integrity issues. The Petroleum Safety Authority Norway (PSA) performed a pilot well-integrity survey based on supervisory audits and requested input from seven operating companies, 12 preselected offshore facilities, and 406 wells. The wells were a representative selection of production and injection wells with variation in both age and development categories. The pilot project indicates that 18% of the wells in the survey have integrity failure, issues, or uncertainties, and 7% of these are shut in because of well-integrity issues. The selection of wells and the companies indicate that the statistics are representative. The well incidents in the past and the results of the pilot well-integrity survey revealed that the industry needs to increase focus on barrier philosophy. Control of barrier status is an important health, safety, and environment (HSE) factor to avoid major incidents caused by unintentional leaks and well-control situations. Knowledge of well-integrity status at all times enables the companies to take the right actions in a proactive manner to prevent incidents. The paper presents the results and the conclusions from the pilot survey. In addition, a number of technical well failures will be presented, identifying critical elements such as corrosion, leaks, and operational factors. In particular, the understanding of barrier regulations, standards, and implementation was found to be inadequate.

This paper presents the challenges related to qualification and testing of well barrier elements related to the long-term integrity test, the exposed medium, the temperature, and how the testing and qualification are performed. The paper shows that the International organization for standardization (ISO)/ American Petroleum Institute (API) standards for well barrier elements such as drill pipe, BOP, packers and bridge plugs, subsurface safety valves, casing and tubing connections, gas lift equipment, and cement can be improved in relation to long-term integrity testing, the test temperature and the test medium.NORSOK D-010 is a well integrity standard developed by the Norwegian petroleum industry and available at www.standardnorge.no. The standard defines the well barriers as an envelope of one or several barrier elements preventing fluids or gasses from flowing unintentionally from the formation, into another formation or to surface. The standard states that the permanent well barrier should have long-term integrity properties. The long-term integrity test of well barrier elements is not described in NORSOK D-010 or in any other relevant ISO/API standard. The industry does not perform long-term integrity tests and this paper discusses the factors that need to be considered.The paper illustrates that the industry needs to further concentrate on qualification of the well barrier elements. The well barrier elements will impact well integrity and the possible degradation of the construction of the wells. The control of the well barrier status and quality is an important HSE factor in order to avoid incidents and major accidents caused by unintentional leaks and well control situations. Knowledge of well integrity status at all times enables the companies to take the right action in a proactive manner and thereby prevent incidents from occurring.

The indications of several well integrity failures on the Norwegian Continental Shelf (NCS) was the motivation for a study to investigate the possible involved mechanism of well integrity issues on the NCS. The study will include water injectors, gas injectors and CO2 injectors. This paper describes a number of technical well integrity issues, identifying critical elements such as design failures, corrosion problems, tubing leakage, operational factors and degradation of barrier elements like cement problems, casing issues and elastomeres failures in injection wells. The study includes a selection of new and old injection wells from different facilities and operating companies at the NCS. The paper will also present some production or injection wells in depleted oil and gas fields that are reused as injection wells. Well integrity and control of the barrier status is considered as an important HSE factor that limits integrity incidents, leaks and well control situations. Knowledge of the well status enables the companies to take the right actions in a proactive manner and thereby prevent potential losses and expenses and to ensure "healthy" & safe wells. Introduction Several well integrity failures in injection wells were reported to the Petroleum Safety Authority (PSA) in the "pilot well integrity survey" in 2006 referring to SPE 112535. The result of the referenced survey was the motivation for a study in 2008 to investigate the possible mechanisms of well integrity challenges on the NCS specifically related to injection wells. The data input in this study is based on format of the questionnaire for 2008 injection well study as referenced in appendix A. This study representing six operators includes water injectors, gas injectors and water alternating gas wells (WAG). Challenges regarding connections and CO2 injection are identified.

The Petroleum industry needs a common industry practice related to design of adjacent CO 2 injection wells and plugging & abandonment of CO 2 injection wells. Adjacent wells are defined in this paper as wells that can be exposed to the injected CO 2 . A CO 2 injection reservoir may be penetrated by a number of adjacent wells that can be potential leakage sources. These wells can be abandoned-, production-, injection-and disposal wells. Adjacent wells can have well integrity issues that can lead to leakage of CO 2 to the surroundings. The paper presents some of the potential reservoir-and wellbore-related leakage pathways.Seismic surveys are performed to verify how the CO 2 medium moves within the reservoir. There are identified challenges related to the verification methods of the structural integrity and how the CO 2 medium is spread within the CO 2 injected reservoir. This can have an impact with regards to the well integrity and degradation of the construction of the adjacent wells.Carbon dioxide can occur in the liquid, solid or gas phase depending on temperature and pressure. When the pressure containment of a well is lost, the carbon dioxide can have phase changes which can lead to very low temperatures in the wellbore. This paper presents the challenges related to qualification and testing of well barrier elements related to low temperatures and the exposed medium.The paper illustrates the industry need to further consentrate on well integrity related to CO 2 injection wells as well as to the adjacent wells. The control of barrier status is a crucial HSE factor to avoid major incidents caused by i.e. unintentional leaks and well control situations. Knowledge of well integrity status at all times enables the companies to take the right actions in a proactive manner and thereby prevent incidents.