The Quantec Force is a new line of polycrystalline diamond compact (PDC) bits featuring newly engineered stabilization technology and new-generation wear-resistant cutters that have delivered unprecedented performance in the Barnett Shale, Travis Peak, Granite Wash, Pinedale, and similarly demanding drilling environments. The design best practices and new technologies that have resulted from significant research and development are now being introduced to the market as the latest generation PDC technology fit to drill in a variety of different applications.

When drilling in hard-rock applications or through the hard stringers of interbedded formations, penetration rates drop, leading to a low depth of cut. With conventional PDC bits, this frequently results in highly destructive whirl. When bit whirl occurs, the cutters are not engaging the formation uniformly, leading to highly inefficient drilling and dramatically reduced penetration rates (ROPs). This phenomenon often leads to premature cutting structure breakdown as well. The end result is slow and short bit runs that increase the cost of drilling the well.

This chart shows the penetration rate achieved and the depth-in and depth-out of the bit run in the Barnett through new PDC bit technology. (Image courtesy of Baker Hughes)

This latest technology advancement employs a proprietary bit dynamics model that optimizes the force distribution to enhance stability and deliver penetration rates that in many cases have been 40% faster than offsets. With the new design methodology, the entire cutting structure is loaded more consistently, thereby optimizing efficiency and stability at progressively higher penetration rates. This increase in energy efficiency makes the newer-generation bits drill faster in soft and hard formations alike. In a variety of demanding applications, the new product line is consistently exhibiting durability and high ROPs unparalleled for a PDC bit in comparable downhole environments. It is now a viable alternative to highly durable but much slower impregnated drill bits, realizing the higher ROPs as well as lower costs without the need for a motor or a turbine.

The new PDC line also incorporates a new generation of application-specific cutters that have been shown to be substantially more wear-resistant than previous designs, providing longer, faster runs. Created with the latest in diamond manufacturing technology, these cutters feature an optimized carbide substrate interface that is critical for balancing cutter stress. Through the use of finite element analysis, residual stresses were reduced considerably, while primary stresses were relocated away from the vulnerable cutting edge

This new generation of cutter technology offers a choice of cutters to address the challenges associated with the needs of various drilling applications. One cutter type is geared specifically for abrasive formations, while another is engineered more to meet the needs of drilling environments where both abrasion and impact resistance are required.

In some applications, strategically placed rows of backup cutters provide the hydraulic and mechanical efficiency of a low blade-count PDC bit but retain the durability of one with a higher blade count, resulting in consistently higher penetration rates.

Providing this design flexibility has allowed the technology to be used in

numerous applications across the US, with those cited above as only a few of the more than 1,800 runs to date as well as a growing number in international markets.

Performance throughout the US

Of the more than 1,800 runs that have been achieved in various well bores across the US, the performance of the first 50 runs was tracked very closely and proved to be extremely strong in comparison with offset performance averages. The new-generation PDC technology drilled 30% farther and 25% faster. Substantial savings have been delivered to operators throughout the US by dramatically reducing the time required to drill wells. The application-specific process and technology is delivering significant improvements in drilling performance in a variety of applications throughout the US. The vast majority of runs have shown either substantial improvement in the distance drilled, ROP, or both aspects of the bit run. This has been a very consistent and pervasive trend as this technology continues to be deployed in other US and international applications.

Specific application — the Barnett

As an example, this case study addresses the first bit run under surface casing in Johnson County, Texas. The objective of this interval was to drill out from surface casing and maintain a tangent angle on a steerable motor assembly at a high ROP. Engineers from the service provider assessed the key obstacles for the application. The challenge was to enhance bit stability such that the impact damage that is often observed while drilling with a steerable motor was reduced. Additionally, it was necessary to provide the required bit steerability for the application while not losing axial aggressiveness to drill ahead at a strong penetration rate. The solution delivered performed as illustrated in Figure 1. This chart shows the penetration rate achieved and the depth-in and depth-out of the bit run. The new technology bit delivered on the promise of drilling efficiently, retaining durability, and providing toolface control to achieve the directional program. More importantly, the run saved the operator 17 hours of drilling time and more than US $28,000 in drilling costs based on a fully burdened spread rate of $40,000 per day.