Application-Specific Bit Technology Leads to Improved Performance in Unconventional Gas Shale Plays

Abstract

Unconventional gas plays in Texas, Oklahoma, and Louisiana have become increasingly important. Operators have produced unconventional gas in these shale formations through better well profiles and completion/fracture technology. One key to the fields' continued success is reducing drilling cost even with the current depressed pricing of natural gas. The two general types of drilling programs are vertical/curve/horizontal profiles and more complex wells drilled from a pad. Each of these well types challenges bit designs. A new application-specific bit design package has been developed for these applications. This new design includes features such as improved stability, steerability, optimized hydraulics, depth-of-cut control, diamond volume management and wear-and durability-optimized cutters.Over the last couple of years, operators and service companies have developed a three-bit program to successfully drill in the Barnett play. The challenge of this vertical/curve/horizontal program is combining two intervals into one bit run, thus reducing the number of bits from three to two and improving the economics in drilling the well. In complex well profiles, steerability and durability are critical. Until recently, many intervals were drilled exclusively with roller cone bits. The advent of the application-specific bit designs has enabled the operators to replace multiple roller cone bits with one polycrystalline diamond compact (PDC) bit. This paper will present case studies from multiple independent operators showing the drilling performance improvement, leading to significant cost savings through reduced drilling time and fewer trips. Similar case studies include those in the Haynesville shale play. Runs in the Barnett play have shown up to 91 % faster rate of penetration (ROP) with run lengths of up to 92% longer footage. In the Haynesville play, bits have shown above average ROP with footage increases of 39%.Operators are rapidly adopting this technology and strategy throughout these fields and similar fields in other markets.