This paper discusses the effective application of a Combination Technologies and Processes that allowed successfull abandonment of wells with Sustained casing pressure (SCP), on the Karachaganak field. The planning and execution processes of SCP elimination are examined.
Previous experience in the abandonment of wells with SCP using existing procedures and methodologies for cement and bridge plug placement, on the Karachaganak field, has not always been successful. In some instances sustained casing pressure reappeared, resulting inadvertently in re-entry for intervention.
In 2015 several SCP wells were successfully abandoned using a combination of technologies. The processes will be described in detail in this paper, including:
Image log to enable selection of the interval for section milling
Section milling - removal of a section of casing
Under reaming to remove remaining cement sheath from the wall of the outer casing
Inflatable Bridge Plug - mechanical barrier for placement in the opened window interval.
Karachaganak is a giant gas-oil condensate field with presence of H2S and CO2. Due to that, during well abandonment SCP issue must be eliminated to comply with Republic of Kazakhstan regulation and oil industry standards. SCP, regardless of its value can pose hazards not only to the environment but also be a source of formation of man-made deposits. To ensure industrial safety, environmental expediency and to meet regulatory requirements, the wells with SCP require regular monitoring.
The above mentioned technologies and processes were successfully implemented in wells abandonment and elimination of SCP on wells in the Karachaganak field. All wells were monitored throughout the year, considering the huge variance in the severe ambient weather conditions throughout, and it was proved that no issues with SCP have reoccurred so far.
This paper provides well construction and integrity teams’ information on a solution that could be used in many other wells around the world. The benefits achieved by the Kazakhstan operator open up opportunities to solve SCP problems and prevent future intervention.