Building a Better Bit

Date: 01/20/2012

Designing bits for formation-specific challenges

Successful drilling operations rely heavily on bit selection. The right bit matched to the formation plays a crucial role in optimizing the rate of penetration (ROP), thus reducing rig time and shortening the time between project commissioning and first production. In addition, the combination of a well-chosen bit, bottomhole assembly (BHA), and drillstring make it possible for operators to drill more-complex extended-reach wells that tie together several formations—rendering otherwise uneconomic reserves profitable.

Bits designed to meet unique challenges

Bringing the bit design process to the laboratory saves significant time and cost compared with iterative field-based methods. Moreover, a digital-based design consistently delivers a bit more suited for the task at hand. Engineers develop dynamic models to recreate and analyze bit behavior over time, pinpointing risks and testing virtual prototypes made with specific challenges in mind.

Dynamic modeling helps increase footage and ROP

Dynamic modeling was used to identify the optimal polycrystalline diamond compact (PDC) bit design for a particularly challenging formation in a deepwater field offshore West Africa. The final design resulted in 165% footage increases per PDC bit run, and 122% increases in ROP achieved. In another example, dynamic modeling helped in the construction of a drillstring that minimized the effects of vibrations created when parts of the BHA and bit drilled formations with different characteristics. A third instance of digital-based design involves a revolutionary PDC bit whose design overcame the most challenging problems associated with hole cleaning in horizontal sections drilled through shale formations.

A recent Oilfield Review article, “Bit Design—Top to Bottom,” details these examples and describes the processes by which today’s scientists and engineers are able to match the bit, BHA, and drillstring to the formation to be drilled.

Visit the Oilfield Review Web site. 

Reference

Centala P, Challa V, Durairajan B, Meehan R, Paez L, Partin U, Segal S, Wu S, Garrett I, Teggart B and Tetley N: “Bit Design—Top to Bottom,” Oilfield Review 23, no. 2 (Summer 2011): 4–17.