Abstract In oil and gas workover operations, maintaining the integrity of well barriers is important to prevent potential well control incidents. These barriers incorporate mechanical well barrier and fluid barrier (kill fluid), collectively ensuring safe operational conditions. Historical drilling cases face the challenges posed by high permeability reservoirs, which have necessitated prolonged effort to cure the losses and activation of Pressurized Mud-Cap Drilling (PMCD). To mitigate such risks, incorporating retrievable nippleless plugs as mechanical barriers emerges as a viable strategy to safeguard against total losses during operations. This abstract discusses a case of workover high temperature carbonate well with high formation losses and challenge to mechanically isolate the reservoir through restricted ID in the well. This one well in Sarawak water, operating at 365°F, encountered tubing-casing communication issues, which led to the well-being suspended due to concerns of well integrity. As a short-term solution, an expandable steel patch was installed across the tubing leak, which reduced the internal diameter (ID) clearance. This constraint posed a significant challenge for deploying standard intervention tool or plugs capable of passing through the restricted ID. To address these challenges, a novel approach was proposed: developing a customized high expansion retrievable nippleless plug with a smaller outer diameter capable of withstanding high temperatures. Additional features included a junk catcher with funnel design connected at the top to prevent debris accumulated around the plug element and a junk extension to capture debris falling into the plug, mitigating any risk on retrieving the plug later. This plug was also equipped with a multi-cycle interventionless glass barrier at the most bottom, serving as a temporary solution for plugging, providing bi-directional barrier capabilities. The glass component was designed to shatter after a pre-defined number of pressure cycle which can eliminate the need to run a prong to equalize the plug before retrieving it and fasten up the equalising process. This innovative solution represented a pioneering effort, necessitating rigorous testing to ensure it complied with international standards (ISO 14310 V0) for barrier integrity, load and pressure, as well as operational reliability in extreme thermal conditions (ISO 14998:2013/V0). The customized high expansion retrievable plug successfully isolated the production zone, enabling subsequent workover operations to proceed smoothly without encountering losses. This outcome not only prevent the need for costly PMCD but also demonstrated cost savings and operational efficiencies in similar high-temperature well scenarios. In conclusion, this case study shows the importance of adaptive engineering and innovation in addressing complex challenges in oil and gas operations. By utilizing advanced materials and design principles, operators can minimize operational risks, and optimize costs associated with well control and intervention measures. This abstract encapsulates where technical achievements meet practical implications for safe and efficient workover practices on high-temperature and high producer well.
Redzuan et al. (Mon,) studied this question.
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