The Sustained Casing Pressure: Periodical Annuli Pressure Survey Campaign Findings in Mature Offshore Oil Field

Abstract

Sustained pressure in oil and gas wells remains a serious challenge that directly impacts the well integrity. This phenomenon commonly appears in aged wells. Well completion elements provide the required isolation to protect the well. Cement prohibits fluid movement between the subsurface formations. Additionally, mechanical isolation packers are employed to alleviate the probability of tubing/annulus communication. In the Arabian Gulf, it is attributable to the presence of a shallow-depth aquifer that contains corrosive water, carbon dioxide, and hydrogen sulfide gases. Surveillance campaigns are performed to ensure the safety and healthiness of well completion components in addition to the reservoir management requirements. The Annuli Pressure Survey (APS) is deemed to be important to identify well integrity problems, especially the sustained casing/casing annulus (CCA) or tubing/casing annulus (TCA) pressure. Wells with sustain pressure are recommended for bleed-off/buildup test to check the communication between the casing sections. The annuli pressure survey campaign is run periodically in a Middle Eastern Mature Offshore Oil Field. Oil producers and water injection wells are surveyed at least twice per year. The most recent campaign for 229 wells revealed that 8.3% of the surveyed wells exhibit sustain casing pressure (SCP), and most of these wells age +20 years. This paper aims to illustrate the findings of the APS on this field. It includes the identification of the attributable factors that might lead to the SCP. It also provides a best practice to monitor the casing strings pressures and ensure well integrity in addition to diagnostic test should be followed to confirm the SCP.