When Baker Hughes first introduced its EZCase casing bit system, operators were able to combine drilling with casing/liner running operations for the first time using a polycrystalline diamond compact (PDC) drill bit mounted on the end of a section of casing or liner. The technology, which can be used to guide casing to an existing total depth (TD) or to drill new formation, won the drill bit category of Hart Energy’s 2008 Meritorious Awards for Engineering Innovation.

Since then, the EZCase casing bit system has set multiple world records by drilling some of the longest and deepest intervals in multiple casing sizes while decreasing nonproductive time (NPT), according to Phillip Pavelka, Baker Hughes’ product manager for casing and liner bits. “Baker Hughes successfully combined a specialized steel alloy body and 100 years of Baker Hughes’ drill bit design and manufacturing expertise,” he said. “The resulting EZCase casing bit enabled casing and liner systems to be drilled down over longer intervals and harder formations while avoiding the need for a dedicated drill-out run. Previously, the needs for performance and drill-out were considered by many to be mutually exclusive.”

When an operator in the Asia-Pacific region decided to drill a section with 9 5/ 8 - in. casing to improve performance and reduce safety and operational risks, Baker Hughes provided a 12?-in. EZCase casing bit designed with hard facing, premium PDC cutters, and backup cutters for added durability. Drilling a total of 1,710 m (5,610 ft) to TD at 1,905 m (6,250 ft), the bit set a world record for longest interval drilled with a nonretrievable casing bit. “The EZCase bit maintained exceptional stability and an average on-bottom ROP of 64.3 m/hr [210 ft/hr] and was drilled out without incident,” Pavelka said. As a result, the operator saved 46 hours of NPT and US $800,000 compared with the previous best conventional drilling performance.

Since introducing the technology, Baker Hughes has made several improvements, including increasing hydraulic efficiency through proprietary computational fluid dynamics software. This has resulted in less balling and erosion. The company replaced the fixed port design with easy-to-change nozzles, allowing total flow area to be adjusted in the field to match application requirements. “Stability has been significantly improved through changes to the cutting structure layout and bit profile,” Pavelka said. “The combined hydraulic and cutting structure optimizations have tremendously improved the overall durability, integrity, and performance of the product.”

The company also introduced EZCase heavy-duty bits for use in more challenging applications, with features like hard facing to protect against erosion-related cutter loss, backup and application-specific PDC cutters, and increased blade standoff to further reduce erosion and guard against balling. In addition, the company’s TORXS expandable liner hanger has seen improvements, with higher torque and RPM capabilities and larger bypass areas. “Now both the liner system and casing bit are capable of performing liner drilling over longer, deeper intervals and in more complex wells,” Pavelka said. The EZCase casing bit system’s many improvements have enabled it to become economical in more applications and allow it to remain a key technology. The company has placed additional focus on development of both nonsteerable and steerable liner drilling systems. Steerable systems that involve retrievable BHAs, though, are still new, complex, and cost-prohibitive in a majority of applications, Pavelka said, so it has not yet eclipsed the need for more “simple” nonretrievable systems. “We are continuously working to improve performance, functionality, and versatility of the EZCase casing bit system,” he added.

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