Versatile Intelligent Circulating Tool to Mitigate Drilling Risks in Highly Depleted Formations

Abstract Drilling in depleted formations presents unique challenges, including differential sticking, and poor hole cleaning due to reduced carrying capacity of the drilling fluid. Wellbore stability issues can arise from changing fracture gradients, causing collapsed formation. Therefore, balancing mud weight is critical to prevent this from happening. Other uncertainty includes losses, which may trigger well control situation. This paper discusses the value presented to overcome these challenges by utilizing a versatile remotely activated downhole tool for flow diversion into the annulus to combat losses efficiently. One of the drilling operations in a challenging well offshore Sarawak, Malaysia, considered utilizing an intelligent circulating tool to help mitigate the risk of losses, well control, and poor hole-cleaning issues. Unlike conventional circulating tools, the intelligent tool does not require any type of drop ball, dart, or tag from the surface to cycle the tool open. The tool can be activated on the fly within 5 minutes, without the need for the string to be stationary or breaking of connections, which generally consume hours of rig time before Loss of Circulation Material (LCM) can be pumped through the string. This is a valuable feature, especially while combating severe losses or in well-control situations. The intelligent tool is powered by battery and electronics and can last up to 4 weeks downhole. Therefore, the intelligent tool can be cycled between opening and closing as many times as required, without the need to pull out of hole to empty the ball catcher. During the drilling of the 12-1/4″ section, 2 activations were done to cure losses by pumping 60 bbls of 65 ppb coarse-sized LCM, and one activation to circulate through pack-off. In the 8-1/2″ section, 14 activations were done to cure losses by pumping 360 bbls of 80.6 ppb coarse-sized LCM. Further losses required different approach. Therefore, 4 cement plugs, up to 200 bbls of 15.8 ppg G-cement were pumped through the intelligent tool to secure the well. Other operations within this section include 4 activations to boost annular velocity for hole-cleaning, with 50% increase in flow rate. In the 6″ slim section, 4x activations were conducted to boost annular velocity, with 60% increase in flow rate, up to 750 GPM. Throughout the entire drilling campaign, 3 different sizes of tools (8.25″, 7″ & 5″ OD Tool) were utilized for 3 different hole sections (12-1/4″, 8-1/2″, and 6″) with a total of 59 activations to facilitate the drilling operation. To pump high density and high solid content fluid like cement or coarse LCM through small openings imposes a risk of plugging bit and logging-while-drilling (LWD) components. Utilizing the intelligent circulating tool above the Bottom Hole Assembly (BHA) eliminates this risk. The intelligent tool carries a seal system to ensure no debris can pass through, protecting the BHA components below the tool.