Conical-Diamond-Element Technology

Smith Bits, a Schlumberger com­pany, has introduced its Stinger conical-­diamond technology. The polycrystalline-diamond element enables high point loading, to fracture rock more efficiently during drilling to increase the rate of penetration (ROP) and durability. Developed with proprietary ­synthetic-diamond-manufacturing technology, the conical-diamond element has an ultrathick polycrystalline-diamond layer that is significantly thicker than that of conventional polycrystalline-diamond-­compact (PDC) cutters. The element’s shape is optimized for strength in axial compression. When centrally positioned in a PDC-drill-bit cutting structure (Fig. 4), the new element improves performance by crushing the formation core at the borehole center, increasing drilling speed. Using the company’s IDEAS integrated-drillbit-design platform, extensive simulations were conducted showing ROP increases in several rock types, including shale, limestone, and sandstone. The virtual drilling environment demonstrated that central placement of this element would yield an ROP increase of at least 18%. In the Williston basin, an 8¾-in. PDC bit typically is used to drill the vertical hole before the curve and the lateral section in the Bakken oil-bearing sands. In field tests, centrally placed conical-diamond-element technology was added to the baseline vertical-section-drill-bit design. Average ROP was increased by more than 46% compared with the next-best performance in offset wells, with a record ROP increase of 77%.

Fig. 4: Smith Bits’ Stinger conical-diamond element is centrally positioned in a PDC-drill-bit cutting structure

 


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