New Cutter Technology Redefining PDC Durability Standards for Directional Control: North Texas/Barnett Shale

Abstract

AbstractThe Bamett Shale play in the Fort Worth basin has become a substantial source of natural gas development and production in the United States. However, successfully drilling to the producing horizontal section requires an ever increasing amount of directional control. It's critical to optimize borehole placement and maximize total lateral footage within the producing horizon to enhance project economics. Additionally, in the vertical/build and hold section the operator must drill the sharp, abrasive Atoka sandstone and Bend conglomerate. These formations usually require several bits/trips to complete the entire section. These formations have historically been drilled with roller cone bits because standard polycrystalline diamond compact (PDC) bits/cutters do not have the required wear and impact resistance to withstand the punishment of the downhole environment without sustaining dramatic penetration rate (ROP) reductions. The operator required new cutter technology to efficiently drill the hardest, most abrasive sections of the Pennsylvanian Atoka sandstone and Bend conglomerate (~80% sandstone). The PDC bit body also needs to provide superior directional control to efficiently deliver the complex borehole geometries.To solve these issues, the service provider initiated a research and development effort to analyze the levels of frictional heat generated at the rock/cutter interface. The resulting high temperature at the cutting tip is a major factor limiting PDC application in challenging hard/abrasive formations. Additionally, PDC's are now expected to drill longer intervals at deeper depths further intensifying thermal degradation and micro-chipping. The multifaceted analysis was aimed at increasing the three key functional properties that dictate PDC cutter life including thermal stability, wear resistance and impact strength. Generally, wear resistance and thermal stability are required for drilling sandstone, siltstone and other abrasive formations, while formations with higher rock strength and interbedded sections require a more impact resistant cutter.