A Structured Approach to Benchmarking Bit Runs and Identifying Good Performance for Optimization of Future Applications

Abstract

Performance analysis of large numbers of bit runs is often anecdotal and uses historical cost data. To this end, there are numerous problems with this approach.  There is no uniform approach to identifying good performance.  At best, the analysis provides an imprecise picture of overall performance.  Large datasets need to be condensed into runs of interest.  Difficulties arise when comparing multiple runs through long intervals with variable thicknesses of hard stringers.  Since BHA, rig, and other costs change over time, it is problematic using historical cost per foot (CPF) data for the current target well.  Finally, how does one determine if long slow runs or short fast ones are better since both could have the same CPF?

In this paper, the authors discuss a structured benchmarking method that can be applied regardless of the application or area studied.  The basic process is simple and can be tailored to the requirements of different applications.  The goal is to deliver a statistical benchmarking process that helps filter large sets of data and facilitates a consistent approach to bit performance analysis that is independent of historical cost data.  A process flow chart is developed to guide engineers step-by-step through the benchmarking method.  Good offsets are identified and included in the benchmarking population.  Eligible bit runs are then ranked by a new key performance indicator (KPI): ROP*Distance Drilled. No historical cost data is included in the analysis.  A detailed engineering study is then carried out on the identified best runs to develop recommendations for future applications.  As the last step of the process, a financial analysis is carried out using cost data for the current well.

The paper will describe the use of this process to analyze bit performance in the operator's gas drilling operation and show how it allowed the identification of ‘true' unbiased top performance. The benchmarking process standardizes performance analysis and ensures sound engineering principles are applied resulting in a better understanding of past performance and better recommendations for future applications.

Introduction

The complexity and variability inherent in the drilling process magnify the difficulties in developing global benchmarking approaches for evaluating performance.  Accordingly, performance comparisons primarily have been undertaken on a well-by-well or actual-versus-plan basis. ^{1, 2, 3}  While a number of industry service-quality programs have been implemented to address trends involving multiple drilling projects, they have been only marginally successful.  Most of those initiatives have sought to correlate drilling costs with key performance indicators (KPIs), individual drilling metrics, and parameters that integrate several KPIs and metrics into a single index. ⁴ For example, the Dodson Mechanical Risk Index (MRI) is a de facto standard that considers well depths, drilling fluid density, the number of casing strings, and various key drilling factors (KDFs) weighted by their projected impact on drilling difficulty.⁵

The Cambridge Online Dictionary defines benchmarking as a method "to measure the quality or performance of something by comparing it with something else of an accepted standard.??  In the exploration sector, drilling engineers try to analyze the performance of bits that drill more or less in the same application.  Within one operator's drilling office, several different approaches can result in varying perceptions of bit performance, thus leading to possible misunderstandings about how performance should be measured.