Development of Work Flow To Manage Fatigue of Bottomhole Assemblies

Fig. 1—S/N curve.

A new fatigue-management work flow provides drillers with a tool to simulate and predict the life expectancy of bottomhole assemblies (BHAs) before fatigue causes problems. This new feature allows engineers to calculate and monitor the fatigue life. It also helps engineers to take appropriate action before a failure occurs downhole or to provide information to the maintenance team for preventive maintenance. Overall, this new approach allows engineers to manage drilling risks related to fatigue before any negative consequences.

Introduction

The oil and gas industry continues to drill wells that are deeper, more complex, and have greater extended reach and dogleg severity. These wells expose drillstring elements to higher loads and several kinds of cyclic stresses. The success of drilling operations relies on maintaining the integrity of the BHA and the drillstring. One of the more common catastrophic events related with BHA integrity is twistoff, where the BHA component parts from the drillstring downhole. Twistoff can be caused by the load exceeding the collar strength or by high shock, vibration, or corrosion, but the primary cause of twistoff is fatigue failure. With fatigue failure, the drillstring fails downhole despite the stress being below the material-strength specification. This is caused by fatigue accumulated over time. According to some reports, fatigue failure contributes to more than 60% of total drillstring failures. Fatigue failure can occur under a wide range of conditions and environments; however, a higher risk of fatigue failure always exists when rotating drill collars and tools through high-dogleg intervals during the drilling.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper IPTC 18682, “Development and Utilization of BHA-Fatigue-Management Work Flow,” by Hendrik Suryadi, SPE, and Phan Van Chinh, SPE, Schlumberger, prepared for the 2016 International Petroleum Technology Conference, Bangkok, Thailand, 14–16 November. The paper has not been peer reviewed. Copyright 2016 International Petroleum Technology Conference. Reproduced by permission.
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Development of Work Flow To Manage Fatigue of Bottomhole Assemblies

01 December 2017

Volume: 69 | Issue: 12

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