The editors and staff of E&P Magazine presented the Schlumberger BDT team with a 2018 Special Meritorious Award for Engineering Innovation during OTC this past May. This recognition honors the StingBlock advanced stabilization conical element cutter block design, which is the product of continuous innovation and engineering domain expertise in bits and drilling tools.

The StingBlock cutter block is engineering artwork, designed to solve one of the most common issues during borehole enlargement operations—cutter block stabilization. Vibration is extremely hostile toward cutter block stabilization, particularly in high-impact applications. Hard and interbedded formations cause conventional cutter blocks to experience higher levels of vibrations during drilling operations, which then decrease stability and steerability. That instability not only decreases ROP, but it also increases damage risks to the entire BHA. Intrinsic to the StingBlock cutter block design is an advanced cutter block profile that incorporate pioneering 3D cutting elements to lower vibrations during hole enlargement while drilling (HEWD) operation.

Distinctive features of the StingBlock cutter block include an increased area on the main gauge pad, as well as additional staged gauge pads. Each terrace on the staged profile efficiently distributes cutter block forces during drilling. And while the cutter block has an optimized set of 2D premium PDC cutting elements, the StingBlock cutter block gets its name and its rock-crushing performance from Stinger conical diamond elements, which are placed in key positions along the main and staged gauge pads.

Schlumberger pioneered 3D, unique-geometry cutting elements, beginning with the Stinger element. Initially used as a center cutting element on PDC bits, the Stinger element has since become the primary cutting insert on StingBlade conical diamond element bits. In either application, this conical element delivers substantial improvement on bit stability and steerability, which is ultimately measured in longer footage, increased ROP, and higher bit durability.

Building on the success of the StingBlade bit, the BDT team incorporated the Stinger element into a cutter block design, aiming to provide the same stability previously seen on PDC bits. The combination of the Stinger element with the staged gauge pad design were proven through several engineering design iterations, along with FEA modeling using the IDEAS integrated dynamic design and analysis platform and extensive lab testing.

The StingBlock cutter block is specifically for use with the Rhino integrated borehole enlargement system. The staged gauge pad design enables optimization for each Rhino system tool size. Depending on factors such as the type of enlargement operation (underreaming while drilling or underreaming only) and the formation intended for enlargement, simulations during the BHA design phase reveal the ideal positioning of the cutter blocks on the Rhino system reamer, as well as the optimum profile adjustment to the pads.

Field tests worldwide demonstrated that the StingBlock cutter block substantially increased tool stability, provided longer footage, and improved ROP by reducing shock and vibration levels. Improved cutter block durability was also recorded, based on evaluating dull grade condition after each run, which included ratings from acceptable to optimal, even while enlarging through stringers or interbedded formations that were highly prone to higher levels of vibrations during HEWD operations.

The StingBlock cutter block earning a Special Meritorious Award not only reinforces Schlumberger as a leader in providing customer-driven solutions, but also reflects the enormous intellectual capacity of its people, including the BDT team, who set the bar in developing efficient and unique tools and innovative services for the oilfield.