Hybrid Bit Technology - Smith BIts/SLB
In a Technical Paper from 2013, Slim Hbaieb and Michael Azar of Smith Bits, a Schlumberger Company explained the advantages of an innovative hybrid bit design that had been tested successfully in Brazil’s pre- salt formations. The main advantages were that the hybrid bit mitigated geological and formation uncertainties, and eliminated the need for several trips to replace damaged bits. Normal PDC (polycrystalline diamond compact) bits can drill pre-salt carbonate rocks effectively until the cutters are damaged by problematic chert inclusions.
The hybrid bit is capable of similar ROP (rate of penetration) and run lengths as standard PDC and allows the operator to achieve a long run at high ROP when no silicate inclusions are present. However, the hybrid bit also provides the added benefit of continued drilling at reasonable ROP when a nodule is encountered with its secondary and tertiary cutting elements. The unique hybrid design utilizes grit hot-pressed inserts combined with alternating PDC shearing elements and wedge shaped TSPs (thermally stable diamond) all set in an impregnated post-on-blade design. Extended bit life is achieved when the cutting mechanism changes from shearing to grinding as the PDC/TSP elements are worn away. When the PDC cutting structure is worn down to 50%, the bit still has 75% of life remaining.
When used with the appropriate BHA (bottom hole assembly) and drilling parameters, the hybrid bit displayed good ROP performance and total footage capabilities. Lower cost/meter was achieved because the hybrid bit had faster initial ROP compared to PDC and stayed on bottom drilling longer due to improved durability with TSP impregnated cutting structures. Engineers are working on a real-time surface/downhole data processing system to detect when the impregnated cutting structure engages formation in order to make changes in operating parameters to maximize drilling efficiency and penetration rates, at this point in time this real-time surface/downhole data processing system should already be operational.