Eliminating Human Error During Coiled-Tubing Operations
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 100164, "Eliminating the Human Error During Coiled-Tubing Operations," by R. Burgos, SPE, M. Allcorn, SPE, R. Mallalieu, SPE, and J. Vicens, SPE, Schlumberger, prepared for the 2006 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 4-5 April.

A study of coiled-tubing (CT) pipe-failure causes over a 5-year period indicates that a substantial percentage of incidents can be attributed to human error. The full-length paper presents an effective means to reduce human error in CT failure. Incorporating a specialized system into the CT-unit (CTU) controls provides a shutdown feature when specific job set-points are exceeded. The full-length paper discusses the features and capabilities of such a system and cites details of recent experiences demonstrating the benefits of the device in actual CT interventions.

Introduction

During the last decade, the oil and gas industry has witnessed continued technology innovation in conjunction with CT use. Primary drivers for these innovations include tougher wellbore conditions and more-complex intervention objectives. The effect of operating failures (OFs) during execution of these high-technology CT interventions becomes more critical. These OFs can be the direct result of equipment failure, procedural inadequacy, product incompatibility, failure in the service organization, and human error. Seldom can the root cause be attributed to a single factor, and often it is a combination of these factors. Overall systems improvement and better service quality can be achieved only through investigation of all failures associated with CT well interventions.

CT-string failures continue to be a recurring issue whenever the subject of OFs is discussed. A study of operating data found human error to be a common cause, although there are other contributing factors. To mitigate the human error element, a specialized control system (CS) has been incorporated into CTUs. Statistics gathered over a 5-year period, from 2001 to 2005, are presented to determine if this CS has been effective in reducing the number of OFs attributed to human error.

CT-String Failures

Use by a major service company of a service-quality statistical database to identify problem areas was the subject of an industry paper in 2001. OF severity was determined by nonproductive time (NPT) and financial loss and is categorized as follows where NPT is total client and service-provider downtime and loss is total client and service-provider losses.Catastrophic operational failure (COF), where NPT is greater than 48 hours and/or loss is greater than U.S. $1,000,000.Major operational failure, where NPT is greater than 12 hours and less than 48 hours and/or loss is between U.S. $100,000 and $1,000,000.Serious operational failure, where NPT is greater than 4 hours and less than 12 hours and/or loss is between U.S. $10,000 and $100,000.Light operational failure, where NPT is less than 4 hours and/or loss is less than U.S. $10,000.