Open data enthusiasts rejoice! There’s a large new openly licensed subsurface dataset. And it’s almost awesome.

The dataset has been released by Dutch oil and gas operator Nederlandse Aardolie Maatschappij (NAM), which is a 50–50 joint venture between Shell and ExxonMobil. They have operated the giant Groningen gas field since 1963, producing from the Permian Rotliegend Group, a 50 to 225 metre-thick sandstone with excellent reservoir properties. The dataset consists of a static geological model and its various components: data from over [edit: 6000 well logs], a prestack-depth migrated seismic volume, plus seismic horizons, and a large number of interpreted faults. It’s 4.4GB in total — not ginormous.

Induced seismicity

There’s a great deal of public interest in the geology of the area: Groningen has been plagued by induced seismicity for over 30 years. The cause has been identified as subsidence resulting from production, and became enough of a concern that the government took steps to limit production in 2014, and has imposed a plan to shut down the field completely by 2030. There are also pressure maintenance measures in place, as well as a lot of monitoring. However, the earthquakes continue, and have been as large as magnitude 3.6 — a big worry for people living in the area. I assume this issue is one of the major reasons for NAM releasing the data.*

In the map of the Top Rotliegendes (right, from Kortekaas & Jaarsma 2017), the elevation varies from –2442 m (red) to –3926 m. Major faults are shown in blue, along with seismic events of local magnitude 1.3 to 3.6. The Groningen field outline is shown in red.

Can you use the data? Er, maybe.

Anyone can access the data. NAM and Utrecht University, who have published the data, have selected a Creative Commons Attribution 4.0 licence, which is (in my opinion) the best licence to use. And unlike certain other data owners (see below!) they have resisted the temptation to modify the licence and confuse everyone. (It seems like they were tempted though, as the metadata contains the plea, “If you intend on using the model, please let us know […]”, but it’s not a requirement.)

However, the dataset does not meet the Open Definition (see section 1.4). As the owners themselves point out, there’s a rather major flaw in their dataset:

This model can only be used in combination with Petrel software • The model has taken years of expert development. Please use only if you are a skilled Petrel user.

I’ll assume this is a statement of fact, as opposed to a formal licence restriction. It’s clear that requiring (de facto or otherwise) the use of proprietary software (let alone software costing more than USD 100,000!) is not ‘open’ at all. No normal person has access to Petrel, and the annoying thing is that there’s absolutely no reason to make the dataset this inconvenient to use. The obvious format for seismic data is SEG-Y (although there is a ZGY reader out now), and there’s LAS 2 or even DLIS for wireline logs. There are no open standard formats for seismic horizons or formation tops, but some sort of text file would be fine. All of these formats have open source file readers, or can be parsed as text. Admittedly the geomodel is a tricky one; I don’t know about any open formats. [UPDATE: see the note below from EPOS-NL.]

Happily, even if the data owners do nothing, I think this problem will be remedied by the community. Some kind soul with access to Petrel will export the data into open formats, and then this dataset really will be a remarkable addition to the open subsurface data family. Stay tuned for more on this.

References

NAM (2020). Petrel geological model of the Groningen gas field, the Netherlands. Open access through EPOS-NL. Yoda data publication platform Utrecht University. DOI 10.24416/UU01-1QH0MW.

M Kortekaas & B Jaarsma (2017). Improved definition of faults in the Groningen field using seismic attributes. Netherlands Journal of Geosciences — Geologie en Mijnbouw 96 (5), p 71–85, 2017 DOI 10.1017/njg.2017.24.

UPDATE on 7 December 2020

* According to Henk Kombrink’s sources, the dataset release is “an initiative from NAM itself, driven primarily by a need from the research community for a model of the field.” Check out Henk’s article about the dataset:

Kombrink, H (2020). Static model giant Groningen field publicly available. Article in Expro News. https://expronews.com/technology/static-model-giant-groningen-field-publicly-available/

UPDATE 10 December 2020

I got the following information from EPOS-NL: