Video: Anticipating Geo-Drilling Hazards by Sharing Geo-Drilling Events Information Nationwide
- Guido Hoetz (EBN B.V.) | Ivo Nijhuis (WellSpec)
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- Society of Petroleum Engineers
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- 2019. Copyright is retained by the author. This presentation is distributed by SPE with the permission of the author. Contact the author for permission to use material from this video.
- Drilling Hazards, Geo Drilling Events, database, best practises, The Netherlands
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Drilling hazards can lead to significant cost overruns during the drilling phase and might cause unsafe situations or potentially harm the environment. Often the local geology, when poorly understood, is the trigger of a drilling incident. By sharing past drilling experience and in particular observations on Geo-Drilling Hazards, via a suitable platform, well planning and risk assessment can be carried out more effectively. After analysing historic drilling reports, observations on drilling incidents have been compiled using a structured approach. Classification schemes allow systematic capture of key information in a format suitable for a database. In this process the observations (facts) during the drilling operation are analysed and classified into a limited number of event types. By interpreting the data in the geological context, the underlying geohazard type has been determined by selecting from a defined (and limited) number of geological causes. The resulting information can be accessed via an online user interface with GIS functionality and advanced analysis options.
The Geo-Drilling Events (GDE) database currently covers some 1000 boreholes from the Netherlands. Around 1400 geo-drilling events have been analysed systematically allowing to identify drilling hazard hotspots in a statistically meaningful sense. Examples of geo-drilling events include stuck tool, gains, losses, H2S. The underlying geological phenomena i.e. the "geo-drilling hazards" include geological conditions such as: fault, swelling clay, or anomalous pressures. By correlating these with other information, in particular seismic data, the risk of geo-drilling hazards in a planned well can be assessed. For example; it appears that 65% of the (strong) overpressures observed in de Zechstein formation are linked to the Platten dolomite member. This unit can often be identified on seismic and this hazard is therefore, to some degree, predictable.
Planned well trajectories can now be screened efficiently for geo-drilling hazards. The GDE Tool based on advanced classification criteria allows to share relevant well information across all operators active in the Netherlands. This includes newcomers, like geothermal operators who carry out a lot of drilling nowadays. The GDE Tool allows everyone to learn from the experience on drilling hazards gathered over the years by oil companies.