Maximizing Capital Efficiency by Expanding the Limiter Redesign Process to Flat Time Operations

Abstract

The operator's drilling efficiency program has been expanded to a Limiter Redesign Process that seeks to optimize all rig time, including flat time. As drilling efficiency gains have been achieved, flat time now accounts for roughly 80% of the total rig time and approximately 70% of the total cost of drilling and completions operations; leaving 20% of rig time for drilling. This fact led to the generation of a comprehensive Flat Time Reduction (FTR) program.The Fast Drill Process has become a well-known workflow to identify hole-making limiters and mitigate them through "relentless redesign to the economic limit of performance". Efforts to increase drilling efficiency continue, and this process has yielded a continuous increase in the overall footage per day and a reduction in flat time within individual hole sections.To address operations that do not include drilling of rock, the operator has launched a similar effort and workflow process which focuses on "flat time" portions of the well construction process. This has become a key focal point in the organizations approach to maximize capital efficiency. The Flat Time Reduction process provides an environment in which operations are optimized while further enhancing a workplace where "Nobody Gets Hurt."This process is yielding significant savings globally and has been accomplished through planning, "real-time" recognition and response, collaboration with service providers, and a focus on Non-Productive Time (NPT) reduction while continuously improving safety performance. Field applications of limiter redesign are discussed in this paper. The purpose of this paper is to present the current status and specific approaches being used to reduce flat time and share the workflow process.In 2004, the operator started a pilot program to determine if drilling performance could be improved by analyzing and reacting to trends in Mechanical Specific Energy (MSE) 1, 2, 3 by rig site personnel on a real time basis. MSE is a performance measurement parameter that approximates the bit's drilling efficiency and is a function of the weight-on-bit (WOB), surface torque, bit rotation per revolution (RPM) and the rate of penetration (ROP) for a given hole size. When the bit is drilling efficiently, MSE will be steady and will approximate the rock's confined compressive strength. When dysfunction occurs, MSE increases

Mitigating Drilling Dysfunction Using a Drilling Advisory System: Results from Recent Field Applications

“…This example was previously reported in Refs. [5,6] in the context of an early field trial of DAS in an offshore environment. The lithology for the section of interest for this previous DAS trial was comprised of carbonates, siltstones, and claystones in an interbedded calcite-cemented abrasive formation.…”

“…The goal of this DAS application was to facilitate drilling through the abrasive sandstone (2,360 -2,460 ft) without pulling the PDC bit, as illustrated in Figure 18. Figure 19 shows the results of applying limiter redesign principles [1,6] to this operation, along with effective management of drilling parameters using DAS. Significant gains were made in the footage of hard-rock interval drilled (abrasive sandstone) and overall average ROP of the hole section.…”

“…An example of such a workflow that has been used by the operator is real-time bit stick-slip surveillance monitoring (see for example Refs. [4][5][6]), which enables virtual real-time observation of stick-slip severity based on surface torque and RPM and a drilling mechanics model of the drilling assembly. Reacting to several interdependent (and sometimes conflicting) performance metrics (MSE, ROP, stick-slip severity) in real-time is a significant challenge.…”