Material Science Innovation Improves Strength and Erosion Resistance of Steel-Body PDC Bits

Published: 07/31/2020

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In the PDC bits market, drillers have two bit body options: Tungsten carbide matrix PDC bits and steel-body bits. While steel-body bits incorporate geometries that are more conducive to efficient cuttings evacuation, they are less resistant to erosion when compared to matrix PDC bits. Even with the addition of hardfacing, steel-body bits lack the durability needed to withstand the harsh downhole environments of most drilling applications. In 2019, Schlumberger introduced a solution that combines the benefits of steel-body and matrix PDC bits: Aegis armor cladding.

Smith Bits product champion Wiley Long explains the development of Aegis cladding and the material science innovation behind the technology that is not only improving the strength and erosion resistance of steel-body bits but also laying the groundwork for emerging fit-for-basin bit technologies from Schlumberger.

What was the motivation behind Aegis armor cladding?

Our research and engineering departments have been exploring the use of additive manufacturing to improve material properties and manufacturing processes over the past several years. Using this innovative manufacturing approach, we focused on enhancing the construction of PDC bit bodies to overcome two key PDC bit challenges. These include the manufacture of components that require ultrahard materials to operate in hostile environments and the highly variable and customized nature of the designs that drillers request. Of the tens of thousands of bits sold and run each year, these consist of thousands of different sizes and types. A key to ensuring our customer’s performance is being able to quickly customize products to meet the application-specific challenges present in their drilling operation.

Through additive manufacturing, we were able to develop Aegis cladding comprising a new tungsten carbide matrix material that is 40% higher strength and 400% more erosion resistance than tungsten carbide matrix materials created with traditional casting techniques used in matrix body PDC bits. Once we developed this new material, the question was just a matter of identifying a practical way of using it that also addresses the market need. We looked at the traditional hardfacing technique used on steel-body PDC bits and determined that Aegis cladding could offer several advantages.

What gap does Aegis cladding fill in the PDC bits market?

By protecting a steel-body PDC bit with the Aegis armor cladding we ensure that customers can get a PDC bit that provides the benefits that both legacy PDC bit body constructions have to offer. The use of a steel base ensures maximum hydraulics performance of a PDC bit design with tall and thin blades that allow cuttings to more effectively be removed from the bit face. And by armoring the blades with an ultraerosion-resistant tungsten carbide matrix material we configure the orientation of nozzles to ensure that fluid energy is directed at the cutter face where it is most needed to enable efficient PDC cutter cleaning and cooling. With the Aegis armor cladding PDC bit construction, customers no longer need to sacrifice drilling performance due to the limitations of traditional bit body constructions.

What differentiates Aegis cladding from conventional manufacturing approaches such as hardfacing?

One of the greatest limitations of conventional hardfacing is that it is typically applied with a manual process by a skilled welder. This means the quality of the finished product will be highly subjective to the competency of the welder. The Aegis armor cladding strips are printed to their desired, finished shape and attached to a precision-machined position on the face of each blade. But even after eliminating the human factor, the real key is all about the erosion resistance of the Aegis cladding material. Even the best hardfacing will still lag in erosion resistance compared with the tungsten-carbide matrix materials used in matrix-body PDC bits. The Aegis cladding material is 400% more erosion resistant than tungsten-carbide matrix. By combining the superior erosion resistance with eliminating the reliance on a manual process we can put the Aegis armor cladding in a class of its own when compared with other hardfacing techniques.

How does Schlumberger verify performance of Aegis cladding in real-world drilling environments?

The validation and verification (V&V) processes are incredibly extensive, even before we pursue field testing in real-world applications. A core value in Sclumberger’s product development process is to ensure that we have first completed rigorous laboratory testing for any new technology before it reaches a customer’s operation. The V&V plan for Aegis cladding included tests that confirmed the strength and erosion resistance of the new material, and most importantly, we validated the attachment technique used was strong enough to mitigate the risk of losing any components downhole. Only after the V&V plan was completed and all hazards properly de-risked did we move forward to field testing.

Aegis cladding has undergone extensive field testing, accumulating more than 150 runs worldwide. The technology has been field tested across all major shale basins in North America, as well as runs in Europe, the Middle East, Russia, Southeast Asia and South America for both on- and offshore applications. With these runs we’ve seen significantly improved erosion resistance when compared with traditional steel-body bits.

A crucial proof point of the technology’s performance was a multiwell field test in Oklahoma for BP. Read the full case study: BP Uses Armor Cladding to Increase Average Bit ROP 36% and Reduce Drilling Time 179 Hours over 8 Runs

How will Schlumberger leverage this new manufacturing approach used to develop Aegis cladding for emerging bit technologies?

Aegis armor cladding represents just a first step in our efforts to realize the abundant benefits available to construct drill bits with the assistance of additive manufacturing. We see great opportunities in leveraging the technology to address how quickly we can respond to our customers’ application-specific requests as well as continuing to explore how we can make stronger materials that can outpace the requirements for drill bits to survive and outperform in the harsh drilling environments around the world.

Wiley Long, Smith Bits Product Champion
Wiley Long, Smith Bits product champion
Article Topics
Bottomhole Assemblies Modern Manufacturing
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