What does a specialist geomodeller do, exactly?
The answer sounds simple on the surface – they bring together data from wells, geology and geophysics to create a 3D subsurface model of an asset.
But when you look a little closer, you find that geomodellers are a unique kind of technical expert, bringing together expertise in the art of creating models and using modelling software with a broad understanding of technical disciplines and the commercial aspects of interpreting an asset.
We spoke with Ingrid Demaerschalk, Expert Geomodeller at Rockflow with 25 years of experience in geomodelling consulting and building reservoir models, to unpack the subject.
Every good model starts with a question
Although geomodelling is dependent on data and deep technical knowledge, the most important aspect of making a model is understanding what it’s supposed to achieve.
You might hear modellers talking about it as “framing a model”, or even “finding the why”. You need a plan for how to proceed before you start loading up data.
The right model isn’t the one that can answer any and all questions you can think to throw at it. It’s the one that can answer the specific questions your organisation has. Any modeller who has been at this game long enough will force you to identify these questions so they can build the model accordingly.
Ingrid recalls interviewing a more junior geomodelling candidate and asking what their first step was in building a model. Their response was to start pulling up all the data they had and inputting it to the software.
“As a follow-up I asked if they would do exactly the same thing independent of what they needed the model for,” Ingrid says. “They said yes, but if you don’t know the ‘why’ behind the model, how can you know what data you’ll need to build it?”
Ultimately a model will be far more effective if it’s focused on answering a single, vital question. If you have limited time, and you usually do, it’s better to quickly make several models that each answer a question brilliantly, rather than one master model that inevitably won’t be masterful at all.
An eagle eye across multiple disciplines
We’ve all heard the phrase, “A jack of all trades is a master of none”. But what’s often forgotten is that the full saying is, “A jack of all trades is a master of none, but still better than a master of one”.
In other words, while a master will excel in their own chosen discipline, a complex task that touches on multiple areas of expertise will call for a broader, jack-of-all-trades perspective. Geomodelling is exactly that kind of complex task.
It’s perfectly possible for a geologist or a petrophysicist to open the software and make a model themselves, but a core part of geomodelling is being able to pull together all the elements that make up a field rather than focusing on one specialism.
“Geophysics, petrophysics, structural geology, sedimentology – they all feed into modelling and you have to be able to make sense of that,” Ingrid says. “An expert geomodeller has to be a kind of pseudo engineer to know what’s important to the engineers consuming the model, for instance.”
The expertise to know which details matter – and which don’t
The importance of being a jack of all trades also plays into one of the most common problems that derails geomodelling – getting stuck in rabbit holes.
“Usually when people start going down a rabbit hole with modelling, it’s because they’re focusing on one thing that’s important to their specialism,” Ingrid says.
“You might have sedimentologists saying they need 20 facies represented in the model when three will do fine, or structural geologists making sure every fault is present even if they don’t have any bearing on what the model is trying to achieve.”
This is where having a geomodeller with a broad spectrum of expertise really comes into play.
As well as knowing what’s important to each individual discipline, a master geomodeller will have the bigger picture view, and will know what’s really needed to answer the project’s questions, and what’s just adding detail for detail’s sake. They know what questions need to be answered, and which techniques are going to get as close to the answers as possible, in the most efficient way.
For example, a company might need a model to answer the question of whether they should drill six wells in a field. Once you have the framing of the model settled, a geomodeller can use their expertise to understand whether the details the geologists and sedimentologists want to include will have any bearing on that question. And if more segmentation of facies won’t change the number of wells drilled, it’s not needed in the model.
“An expert geomodeller isn’t necessarily going to avoid every rabbit hole in the first place,” Ingrid says. “But they will recognise when you’re in one, and how to back out of it before you get too far.”
Automation, efficiency and commercial focus
In the oil and gas industry, it’s rare to find any project that isn’t time-bound in one way or another. And with that in mind, part of the role of a master geomodeller is to find the most efficient path forward.
Part of that comes down to the geomodelling tools themselves. The software we use is loaded with automation to speed up certain parts of the modelling process, but not everyone is aware of what those functions are or how to use them.
“If you’re only using the tools once every five years because geomodelling isn’t your speciality, you’re not going to know how to get the most out of it,” Ingrid says. “People don’t use the automation because they don’t know it’s there, or because writing ‘if’ statements and ‘while’ loops in Petrel sounds scary.”
But making the best use of automation is only part of it. Geomodellers also have to bring their experience of past projects to balance the need for detailed models with the commercial aspects of not holding a project decision up.
“The 80/20 rule is a classic in geomodelling,” Ingrid says. “What you want to find is 80% of the solution in 20% of the time. 80% of the solution might not sound ideal but it’s usually enough to answer the uncertainties you have.”
Sometimes that might mean building more than one model. When a project has different questions that need to be answered at different stages, an experienced geomodeller is able to break down which questions have priority, and where there is an opportunity to build quick models for each question rather than one all-encompassing model.
For more on the value a specialist geomodeller’s experience can bring to the decision-making process, read more about Ingrid or take a look at our article on when to call in external expertise.
