This graph shows drill bit history in the challenging Granite Wash of the Texas Panhandle. Roller cone bits in 2003 averaged about 16 ft/hr (4.8 m/hr). Hughes Christensen’s Genesis PDC was the first PDC bit to consistently drill the section at nearly double this ROP, averaging 30+ ft/hr (9.2+ m/hr). The Quantec line has taken this performance to the next level with ROP averaging nearly 42 ft/hr (13 m/hr) or 156% faster than the roller cone average. (Image courtesy of Hughes Christensen)

Hughes Christensen has designed Quantec polycrystalline diamond compact (PDC) bits capable of drilling through extremely abrasive formations. In developing the Quantec bits, the company invested 4,000 hours of laboratory time and drilled 6,000 ft (1,830 m) of rock in its drilling technology laboratory. The bits underwent full-scale, high-pressure drilling simulating and rig tests. More than 2,400 field runs were made with the Quantec cutters before the design was finalized.

Testing resulted in optimized hydraulics to improve cutter cooling, cleaning, and gauge durability to minimize stick-slip.

Diamond volume management

Quantec PDC bit design uses diamond volume management (DVM) to add diamond at critical locations on the bit based on the target application. In some cases, the refined bit profiles are complemented by strategically placed backup cutters. These profiles have the hydraulic and mechanical efficiency of a low-blade-count PDC while retaining the durability of a high-blade-count PDC.

Enhanced cutting mechanics

The new interface between the diamond and carbide surfaces of Quantec cutters are modeled using finite element analysis (FEA), which simulates the residual stress distributions caused by thermal loads. Using FEA, engineers moved the harmful residual stress away from the cutting edge to reduce cracks, significantly increasing cutter life.

The Quantec cutter’s single-layer diamond table technology delivers abrasion resistance with less potential for chipping or fragmenting along the boundary between the diamond layers and ensures greater cutter integrity.

Operator saves nearly $1 million

Offshore Norway, an operator chose a 121⁄4 in. QD507X bit to drill in hard chalk and limestone. The challenge was to drill an S-shaped well to section total depth, drill a vertical section to 5,036 ft (1,535 m), then kick off to 19°, and drop back to 0°. The Quantec PDC bit drilled the section in one fast run, recording no stick-slip. Rate of penetration (ROP) at 98.4 ft/hr (30 m/hr) was 130% faster than the offset of 42.7 ft/hr (13 m/hr). The operator saved 2.7 days and US $950,000.

Large-diameter PDC

In large-diameter holes, PDC drilling is challenged by high torque and excessive vibration. These problems result in shorter runs at a relatively low ROP and often damage bottomhole assembly components. For 16 in. and larger holes, Quantec steel PDC bits address these challenges with strategically engineered technology, including high-performance, application-specific cutters appropriate for the formation.

DVM optimizes the profile and cutter position for minimal vibration, and EZSteer depth-of-cut control technology offers directional control, reducing bit reactive torque to manageable levels. The Lateral Movement Mitigator delivers secondary stability, and in-house computational fluid dynamics has led to maximized hydraulic performance.

In an application of a 26-in. high-imbalance-designed Quantec steel PDC test bit with EZSteer technology and enhanced hardfacing in a deepwater well in the Gulf of Mexico, the bit drilled 1,822 ft (556 m) (~600 ft or ~183 m of salt) at an average ROP of 45.7 ft/hr (14 m/hr).

This 26-in. PDC bit single-run footage record combined with the same bit’s first run ? without repairs between the runs ? saved the customer more than $1.2 million.