A work flow that combines optimization of the drillstring and bottomhole-assembly (BHA) design during well planning and then applies advanced surveillance tools to a well-trained drilling crew yields reduced vibrations and higher drilling rates. This methodology is based on the premise that an efficient drilling operation requires optimized tool designs, advanced diagnostics using real-time drilling parameters, and on-site training of efficient drilling practices and the proper use of rig-control systems.
Introduction
In recent years, as part of a limiter-redesign process and rate-of-penetration (ROP) optimization effort, the operator has sought to develop and validate in the field a suite of tools specifically directed toward drilling-operations support. Vibration-mitigation efforts are a subset of the entirety of this broader program.
BHA redesign involves planning to change the downhole tools. Once a BHA has been selected and its rotary-speed sweet spot is known, there is a real-time component as the driller determines how good the sweet-spot prediction might be or if an alternative operating condition is preferred.
Drillstring modifications on the basis of torsional string modeling typically involve drillpipe-outer-diameter selection and understanding or optimizing the equivalent-circulating-density (ECD) profile, typically resulting in the largest pipe that satisfies the ECD criteria being desired, provided that torque-and-drag modeling do not indicate rig limitations or buckling concerns.
