Schlumberger

Technical Paper: Risk-Based Reliability Engineering Enables Improved Rotary-Steerable-System Performance and Defines New Industry Performance Metrics

Society: SPE
Paper Number: 98150
Presentation Date: 2006
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Abstract

Rotary Steerable directional drilling and logging assemblies deliver significant value to operators through improved drilling efficiency, precise well placement and effective formation evaluation. System failure is associated with a high cost and a high pain factor. Non-productive time (NPT) is used to re-run the failed bottom-hole-assembly (BHA); hole section objectives may be compromised and there is even the potential for loss of hole section, requiring a re-drill.

This paper describes a risk-based approach to quantify and improve the reliability and performance of directional drilling bottom hole assemblies. Extensive field data gathered while drilling fifteen million feet of hole between 2003 to 2005 has been used to drive a reliability centered design and maintenance program with the objective of improving drilling performance, improving system reliability, increasing average rates of penetration and reducing NPT. All aspects of service delivery are considered, including mechanical and electrical system component performance, repair and maintenance procedures, job design and field operating practice.

The approach has yielded measurable improvements in rotary steerable and logging while drilling bottom hole assembly reliability and performance. Industry metrics such as mean time between failure (MTBF), feet drilled per circulating hour (FPCH), feet drilled between failure (FBF), failure free runs and operating efficiency (ratio of NPT to operating time) are considered, benchmarking current performance and setting performance expectations for existing and future downhole systems. The industry has a need to standardize the method of evaluating downhole drilling system performance and to understand and quantify the benefits and risks associated with the application of a specific downhole system in a given downhole environment.

This paper proposes such a standard approach, using novel BHA performance measures and an assessment of BHA complexity and well difficulty.

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