This paper describes an innovative concept for the smallest polycrystalline diamond compact (PDC) cutter size with non-planar diamond table used on a fixed cutter drill bit. This unique PDC cutter significantly increases durability, enhancing the bit life to drill more footage in multi-lateral applications driven by motor or turbine in two different challenging formations. Collaboration between a national oil company and a drill bits provider resulted in achieving consistent records in footage while maintaining good rate of penetration (ROP). This 8.2 mm diameter PDC cutter equipped with unique geometry was used on a 3.625 in. fixed cutter (PDC) drill bit design. Main objective of the unique geometry on this non-planar diamond table is to improve cooling efficiency compared to the standard diamond table of a PDC cutter. Traditionally, PDC cutter technology relies on the cutter's thermal stability and abrasion resistance. Often, those two properties may not provide sufficient durability in abrasive formations. Initially, this unique geometry was used on bigger PDC cutters including 13 mm and 16 mm where a performance improvement was achieved, leading to the decision to scale-down to the smallest PDC cutter size. Two different 3.625 in. fixed-cutter drill bit designs were used with non-planar diamond table PDC cutters and successfully passed the client requirement and trial testing criteria. Based on the field deployment results, drilling performance in the field was monitored and compared to standard diamond table PDC drill bit designs also used in the past as the benchmark. Shaped non-planar diamond table bit designs surpassed the footage of standard diamond table PDC cutter bit designs by 12% and 36% respectively with two different bit designs. Other performance aspect including dull condition were also monitored and showed similar wear progression as seen with other bit designs used in the application. This innovative concept demonstrates that the non-planar diamond table PDC cutter successfully delivers more footage per bit run. This led to increase overall performance with deployments on coiled tubing drilling rigs across this difficult drilling environment in the challenging wells drilled in the Middle East. The novel technology achieves all drilling objectives with fewer drill bits and fewer trips, delivering the target footage at improved ROP.

Drilling operations in the Middle East contain many applications where extended reach laterals target hard and interbedded carbonate reservoirs. Such applications are associated with elevated levels of drilling dysfunctions resulting in tool reliability and bit durability issues. These challenges include lateral and torsional vibrations that impact the drilling system longevity and premature cutting structure damage resulting in multiple drilling trips and an increase of nonproductive time (NPT). To address the lateral stability and loss of drilling efficiency challenges of drilling hard carbonates, this paper explores three new concepts applied to drill polycrystalline diamond compact (PDC) bit design. The 5.875′ Slimhole section through hard carbonate of the Middle East was identified as the target application. A study of existing PDC drill bit performance in this section was conducted to determine current design limitations and set objectives. After optimizing the cutting structure and overall PDC bit frame, three new design concepts were also incorporated. Targeting lateral stability, a "chisel" shaped diamond element (SDE) was placed trailing the cutting structure to provide a stable drilling response. Multiple iterations were studied to optimize the bit lateral stability without compromising bit efficiency. The iterations included changing the radial position, the count and orientation angle of these elements. Non-planar faced PDC inserts were strategically placed on the bit cutting structure to reduce the cutting temperatures during rock cutting, and increase the drilling efficiency. Depth of cut control (DOCC) rubbing elements are commonly used to mitigate stick-slip dysfunctions, but standard DOCC elements wore down too quickly to maintain their function. An impregnated blade based DOCC rubbing element was implemented to maintain the stick-slip protection throughout the length of the run. The new PDC bit design completed six successful field trials in the target section and achieved an average increase of 39% in footage and 11% in rate of penetration. Validation of the design concepts via comparing surface data, downhole vibrations data and the bit dull condition showed marked improvements in the desired metrics. A step change improvement of 50% in the level of lateral vibrations and torsional stability was achieved due to the combination of the SDE and the impregnated DOCC elements. The bit drilled consistently smoother protecting the bit & BHA. Final dull conditions also improved with a reduction in broken or chipped cutters across the cutting structure due to MCE inserts. Combination of innovative geometries and materials targeting stability and efficiency significantly increased performance, reduced NPT and lowered tool maintenance costs in one iteration.