IOGP Well Control Incident Lesson Sharing
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New technologies (e.g. MPD) & Human Factors vs. well control basics

Recently there has been a succession of well control events for which root causes were associated with lack of understanding of the technology and associated procedures, leading individuals to forget basic rules such as shutting-in a well at the right moment in time.

This Well Control Lesson sharing is another example of risks induced by the introductions of new technology.

A number of lessons learnt from similar incidents have been contemplated and a thorough analysis captured in IOGP info sheet ‘Managing the introduction of new technology in well operations’. This document can now be downloaded at Managing the introduction of new technology in well operations | IOGP Publications library.

In this case the lack of communication between Geologist and Drillers did exacerbate the issue.

The IOGP Wells Expert Committee/Well Control Incident Subcommittee believes that this incident description contains sufficient lessons to be shared with the industry. We further encourage the recipients of this mail to share it further within their organization.


The incident occurred while drilling ahead a 12-1/4” section with MPD in a high angle well (MW 11.2ppg / static underbalance + Continuous Surface Back Pressure). A change in cuttings was observed and the shakers began blinding off. A gas spike at the shakers occurred and the well was Shut In.

Gain detected only when at surface, thanks to shaker overload & gas peak (postmortem gain evaluation to 80bbls).

Well control was properly managed:

  1. Control influx being in the riser first
  2. Then performed 1st circulation Driller Method though BOP & Choke. Used MPD to evaluate required Equivalent KMW
  3. Displace 11.7ppg heavy mud through BOP
  4. Isolate kick zone with cement plug through BHA (managed pressure cementing) - abandoned BHA

What Went Wrong?:

Several factors contributed to the well control incident:

  • Unexpected pressurized reservoir in an intermediate section of the well
    Lack of communication between Geologists & Drillers. Realtime monitoring Sonic was indicating an increase in PP for several hours, data not shared.
  • Continued to drill with significant RCD bearing leakage. Volume of mud leaking was routed to trip tank, jeopardizing the monitoring of the active volume & EKD flow in / out measurement. Contributing to the volume of gain.
  • The potential implications of drilling ahead while LWD indicators suggested pore pressure at ESD/ECD were not identified or considered.
  • Significant RCD Bearing leakage contributed to the incident.
  • Interviewees indicated that well monitoring with MPD is challenging compared with conventional drilling.

Corrective Actions and Recommendations:

PPFG trends to be plotted in real time against the PPFG prognosis used during the planning of the well. Any deviations from the plan need to be communicated to the operation team in a timely manner. Communication protocols need to be established and tested to allow this to happen effectively. Any changes in PPFG need to be evaluated against the design assumptions, and the implications understood by the operations and engineering teams.

The vendor to proceduralize requirements for RCD bearing usage including installed hours before a hard redress and maximum leakage rate.

Document MPD Strategy, including the following:

  • Agree volume monitoring procedures, including alarm settings and monitoring, while the MPD system is in use. The use of an MPD system does not override normal PVT practices and needs to be agreed and communicated ahead of starting drilling operations that utilise an MPD system.
  • Develop a well control training plan to address well control while using an MPD system including competency assessment criteria.
  • Conduct an engineering/HF review of MPD-related HMI i.e. how well monitoring data is presented to stakeholders.
  • Verify that the Drilling Contractor's MPD Fingerprinting and Tuning procedure is updated with fingerprinting requirements with an emphasis on the training purposes of fingerprinting.

Reference IOGP info sheet Managing the introduction of new technology in well operations | IOGP Publications library

safety alert number: 326
IOGP Well Control Incident Lesson Sharing


Whilst every effort has been made to ensure the accuracy of the information contained in this publication, neither the IOGP nor any of its members past present or future warrants its accuracy or will, regardless of its or their negligence, assume liability for any foreseeable or unforeseeable use made thereof, which liability is hereby excluded. Consequently, such use is at the recipient's own risk on the basis that any use by the recipient constitutes agreement to the terms of this disclaimer. The recipient is obliged to inform any subsequent recipient of such terms.
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