Abstract
A drill-bit supplier provided mills and bits for drilling out fracturing plugs for a new project in the Vaca Muerta formation in Argentina; however, it was difficult to locate information on similar experiences elsewhere. This paper presents the experience gained during execution of a completions project that included fracturing plug drillouts.
Several technologies were used, and their performances are reviewed, including mills, roller-cone bits, and polycrystalline diamond compact (PDC) bits. Drillout times, size and shape of debris, hole cleaning, and tool dull grades are analyzed. All operations were performed with coiled tubing (CT) equipment. Other parameters considered in the analysis include drilling parameters, number of runs to complete a well, plugs per run drilled, and tolerances with respect to casing drift. Some problems that occurred during project execution are discussed, such as motor stall and casing deformation.
The operations were performed in a combination of horizontal and vertical wells. More than 500 fracturing plugs were drilled out in more than 60 wells, gaining sufficient experience to derive significant conclusions. To help reduce drilling time, improve economics, minimize risks, and reduce CT system fatigue, the five to six-blade PDC bit was verified as the best option in this context. This drill type has an acceptable rate of penetration (ROP), does not risk losing moving parts, and minimizes motor stall. When tolerance with respect to casing drift is correct, the five to six-blade PDC bit also minimizes debris size, which helps reduce stuck-in-hole risks and improves subsequent well production.
Several statistics, images, and resolved issues are presented to advise future CT and well intervention projects. Conclusions regarding various plug types, materials, and drillout procedures are also explained to aid similar projects.
