Utilizing Electronic Data Captured, at the Bit, in Combination with Automated Bit Dull Grading, to Improve Bit Design Features, Dull Condition, and Ultimately, Drilling Performance

Historically, downhole vibrations at the drill bit have been difficult to determine and measure. In addition, oilfield personnel has dull graded bits through visual inspection, which introduces subjectivity into the assessment of the dull condition. Tools to measure dysfunctions at the bit to help understand the root cause of bit failure, and a digital bit imaging system for reliable dull grading, have been a gap in understanding drill bit performance. This paper presents a field study where downhole measurements and automated dull grading were utilized in tandem to improve performance. In the Permian Basin, one of the most challenging applications is the production Vertical+Curve+Lateral section, due to interbedded transitions while drilling, the inability to track tangents, and building curves. The type of vibrations at the bit and their sources were unknown, and determining bit wear location and the type of cutter damage was also a challenge in this case. A sensor at bit to measure downhole dysfunctions, in combination with a digital imaging system that calculates the bit damage, was used to carry out a comprehensive engineering analysis to determine the bit design changes needed for enhanced drilling efficiency. The high-frequency data recorded at the bit showed lateral events of high magnitude that indicated formation-related issues. The automated dull grading system showed catastrophic damage in the cone, along with breakage and delamination of the cutters in the lower shoulder and gauge areas, due to cutter overloading during the lateral vibration events while drilling through hard stringers. The vibrations at the bit were studied to understand how they were generated and how we can mitigate them. The recorded electronic bit data and the outputs of the digital bit dull grading system were analyzed together to determine drill bit features that need to be improved. Based on the bit data recorded and digital dull bit analyses, an advanced bit profile and cutting structure layout with a more impactful placement of depth-of-cut (DOC) control elements were used to develop a fit-for-purpose drill bit design combined with a new generation of PDC cutters. As a result, a complete drill bit design solution was developed to drill longer runs with better dull condition and very consistent performance across the basin. This paper describes the nature of downhole vibrations at the bit and their consequences of damaging the bit through poor drilling performance. A new digital, automated dull grading system accurately determined the detailed location, on the bit, and type of wear produced by the vibrations, and it offered practical recommendations for improving performance. Detailed field data from different runs, showing where bit design changes reduced the failures and resulted in longer intervals drilled, will be presented.