Integrated Work Flow Mitigates Drilling Vibrations
Authors: Wilson Adam 
Published: August 2017

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 183550, “An Integrated Work Flow To Mitigate Drilling Vibrations and Increase Daily Footage,” by J.R. Bailey, SPE, and P.E. Pastusek, SPE, ExxonMobil Development Company; H. Al Junaibi and M. Al Awadhi, National Drilling Company; Y. Al Katheeri, SPE, M.R. Niznik, and K.S. Akyabi, Zakum Development Company; and C.G. Page, Exxon Neftegas, prepared for the 2016 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 7–10 November. The paper has not been peer reviewed.

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. Torsional string modeling provides the capability for real-time stick/slip detection on the basis of monitoring the surface torque variation.

A drilling advisory system (DAS) is, first and foremost, a real-time dysfunction-recognition and response tool. The DAS provides the driller with diagnostic data and charts illustrating the drilling-performance map in a stoplight format to select the best operating parameters.

Rig-control systems, in particular the autodriller, may generate a certain amount of dysfunction as a result of the way they are implemented and operated. Significant changes in drilling line feed rate result from on/off control systems, high control-system gains, and unstable feedback mechanisms in certain situations. These line-feed-rate perturbations may exacerbate other vibration modes, such as stick/slip, resulting in dysfunction and reduced drilling performance.

Efforts to mitigate these effects contribute to the reduction of nonproductive time. Taken together, they have yielded improved drilling results, increasing the number of single-bit runs to section depth in fewer days.