Abstract

The most traditional polycrystalline diamond compact (PDC) cutter technology is composed of a flat surface that contacts the rock to be sheared and removed throughout the drilling process. The necessity to overcome engineering limitations related to PDC capability drove the industry to innovate cutter shapes and 3D surfaces to interact with the rock.

A new hyperbolic diamond element (HDE) bit has been developed to improve drilling efficiency in soft formations compared with conventional polycrystalline diamond compact (PDC) cutters. The design concept and bit utilization theory, laboratory validation, including full-scale drilling simulator testing, implementation of the time-based dynamic bit and drillstring modeling system, as well as the operator's field drilling results from the Niobrara shale play of the DJ Basin, Colorado, USA are presented.

The HDE development, from concept to validation and field deployment, consisted of a multidisciplinary approach that combined proprietary knowledge, manufacturing, and computational analysis. Creating the HDE concept required an overall understanding of shaped diamond elements (SDEs), their applicability, field results, and mechanical properties and outputs.

After creating the concept, proprietary manufacturing processes, single cutter-rock experiments, and full-scale bit-rock testing were used to validate the innovative new SDE. Based on success with the baseline drill bit design—a PDC bit with a different SDE—as well as results from implementing HDEs into a time-based dynamic modeling system used to predict field performance improvements, a DJ Basin operator agreed to test the new HDE bit.

After the first 10 field tests, the HDE bit resulted in a 20% improvement in overall ROP compared with the baseline PDC bit design. The HDE drill bit improved drilling efficiency and lowered mechanical specific energy (MSE) in both the rotating and sliding drilling modes. These results were in line with full-scale bit-rock testing, which indicated a 10 to 20% ROP improvement for the same weight-on-bit (WOB) in various formation types. Furthermore, the results were obtained without increasing bit torque, which is a performance parameter important for positive displacement motor (PDM) -driven bottomhole assemblies (BHAs).

Field testing also indicated that the cutting structure durability was improved, which increased drilling system reliability for the operator. Insignificant or no damage was observed over the HDE bit cutting structure after field tests. The new HDE drill bit efficiently transfers drilling system energy into formation removal without increasing reactive torque to uncontrollable or catastrophic levels. Due to rock-cutting efficiency and cutter durability improvements, SDEs are quickly replacing PDC cutters in various drilling applications worldwide. The concept and laboratory validation delivered a unique and innovative cutting technology for soft formations. Field experience and software modeling combined BHA and nonbit factors during the HDE bit design process to achieve the field performance using the new technology.

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