DIAGNOSTIC AND PERFORMANCE ANALYSIS OF DRILLSTRING VIBRATIONS IN ZUBAIR FIELD

Abstract

In order to improve the drilling performance and prevent the drillstring damage, it is required to reduce the drilling vibrations of wells. Consequently, the main aim of paper is to diagnose and analyze the drilling vibrations for Zubair field wells. Types of the vibration modes are identified, their relative causes, and mitigated actions are then recommended. Further, these vibration are degreed and classified in order to determine the severity degree of each run in drilled wells. Drilling parameters are also plotted and their trend-lines are constructed so as to predict the best ones in future activities. It was found that most of wells' runs were subjected to a severe stick-slip due to highly torsional vibrations and they were required an intermediate reduction of these vibration by reducing the surface WOB and increasing RPM. Additionally, ZB-311 Run 400 and ZB-349 Run 600 were subjected to highly stick-slip and BHA whirl, and BHA whirl respectively. Finally, drilling parameters' plots showed non-uniformity and irregularity fitting between themselves.

Keywords

• drillstring vibrations
• stick-slip
• diagnostic study
• mitigations
• drilling parameters