Improving Marcellus Shale Performance Using PDC Bits with Optimized Torque Management Technology, Cutting Structure Aggressiveness and Unique Roller Cone Steel Tooth Cutting Structures

Abstract

Abstract The low formation unconfined compressive strength (UCS) and low abrasiveness in build and horizontal sections of a Marcellus shale well, relatively green PDC and roller cone dull bits, and the desire to drill fast at high build rates with one bottomhole assembly (BHA) facilitate the use of PDC bits with aggressive cutting structures and new torque management technology. Aggressive PDC cutting structures that inherently drill at higher ROP generate high differential torque and erratic toolface leading to insufficient build rates. If lower energy input to the PDC or less aggressive bits are employed to manage torque, instantaneous rate of penetration (ROP) can be lower. Along with this, drillstring friction can result in less consistent and lower weight on bit (WOB), or high differential torque requiring lowered operating parameters and additional toolface resetting. Due to these issues, instantaneous ROP and feet per day will be lower. This can also affect downhole tool loading and reliability and also toolface control, which can reduce build-up rate (BUR) capacity. In build sections where PDC bits do not demonstrate planned build rates, roller cone bits are run to achieve the planned well path. The roller cone bit is used to manage torque and a unique tooth design is used to increase ROP over traditional bits. This paper investigates the implementation and optimization of new torque management technology combined with the use of managed cutting structure aggressiveness of PDC bits and a unique roller cone bit cutting structure to determine the effects on operating parameters, toolface control, build rates, well path trajectory, cutting structure efficiency, feet drilled per day, instantaneous ROP and time savings. Employing the new torque management technology on optimized, aggressive PDC cutting structures can result in faster drilled sections due to higher instantaneous ROP and less time spent in non-productive steering operations.