Successful Operation of Fluid-Loss Isolation Barrier Valves in Debris

Abstract

This paper demonstrates the importance of wellbore cleanliness during lower, intermediate, and upper completion installations that lead to both successful installation and operation of an isolation barrier valve. This should result in bringing the well into production or injection in a timely and efficient manner. Excessive debris remaining in the wellbore can complicate and delay production or injection and also compromise well productivity by causing damage and preventing installed equipment from operating properly. Post-production/injection debris in the well can also impact and affect production and injection rates. Downhole tools in deepwater environments not operating remotely as designed because of debris can result in a complex and costly intervention. Typically, when this occurs, a drift or bailer run is conducted to establish holdup depth. In some cases, these have tagged up to 50, 80, and 100 ft (in extreme cases, 150 ft) above the valve expected to operate. Sometimes, slickline, electric line (e-line) bailers, coiled tubing (CT), or a work string with a Venturi junk basket are used, and then the valve is either functioned open or the debris is milled out and the valves remotely functioned cycled open once all the debris is removed. Additionally, cases have occurred where the debris is cleaned out, enabling the tool to function and open, depending on tool design. The tools can be designed and qualified to industry standards and tested at downhole conditions, pressure, and temperature with applied tubing and simulated hydrostatic pressure; however, this does not mean functionality cannot be impaired. The importance of wellbore and surface equipment cleanup should not be undervalued. Wellbore cleanout, circulation, displacement, and correct conditioning of fluid are important during the final stages of the operation. If executed properly, these can result in the well entering production or injection on time and without issue. The criticality of robust procedures cannot be overlooked. Not only is it important to condition and displace drilling fluid with clean completion fluid, it is also important to ensure that all debris is removed, including jetting the blowout preventer (BOP) and wellhead cavities before running the completion. Additionally, particular attention should be given to the landing string, tubulars, and drillstrings used to land and lock the completion. All surface lines and pump cavities should also be cleaned before pressure testing. Due diligence during initial cleanout can enable successfully bringing the well on-stream and help prevent costly interventions.