If there is one positive aspect to this day and age, it is the ability to form solid working relationships even when people are living at opposite ends of the world; Martin enjoys the French sun near Montpellier, whilst Lukasz makes the most of Adelaide’s moderate climate. Both grew up in Germany though, but they never met each other.
It was at a conference that they shook hands for the first time. It was 2019, and the AAPG had organised what we now know as the last Hedberg Conference in Houston. It was attended by the world’s leading basin modellers and petroleum systems analysts.
“There were a lot of big names around,” says Martin. “Seasoned experts were celebrated for their lifetime achievements in organic geochemistry, and basin modelling experts presented the future of basin modelling. It was a highly specialised conference, but it was very theoretical and, in my eyes, it was lacking pragmatic and decision-focused approaches.”
A PUB AND A NAME
The name top-down PSA as a methodology was coined in a pub by industry stalwarts Zhiyong He and Andrew Murray, two passionate members of the petroleum systems analysis community. Zhiyong is the driving force behind the Zetaware software, and Andrew Murray has been consulting for more than ten years following a career as Woodside’s principal advisor on petroleum systems.
Top-down and bottom-up
“It was the first time I attended a conference focusing exclusively on petroleum systems, meeting the gurus,” adds Lukasz. “The majority of workflows presented were very labour-intensive, focusing on fully coupled 3D basin models. I was mentored by Zhiyong He and Andrew Murray, advocates of a more practical approach to petroleum systems analysis (PSA) with a strong focus on “top-down” PSA.”
“Bottom-up petroleum systems modelling is the classic approach that comes with reconstructing the 4D structural, depositional and thermal evolution of sedimentary basins. Combining this with source rock parameters, hydrocarbon generation, expulsion, migration and retention is subsequently predicted, as part of a process-based numerical simulation,” explains Lukasz.
Top-down PSA starts at the other end of the spectrum, relying much more on studying the hydrocarbon PVT, geochemistry and seal properties of fields and discoveries… those workflows are much faster, allowing for quick scenario testing and probabilistic predictions
“Top-down PSA starts at the other end of the spectrum, relying much more on studying the hydrocarbon PVT, geochemistry and seal properties of fields and discoveries. Modelling is not necessarily part of the study, and if it is, it is mostly done in a very pragmatic way, using 1D simulation or map-based workflows. This allows people to make predictions on the type of hydrocarbons without the need to create a basin-scale model. And because we do not rely on large grids or complex algorithms, those workflows are much faster, allowing for quick scenario testing and probabilistic predictions,” adds Lukasz.
Papua New Guinea
Lukasz presented his top-down PSA study in the Papuan Basin in Papua New Guinea. Without trying to reconstruct the 3D basin history, Lukasz was able to make a case for oil discoveries being primarily associated with structures that have undergone thin-skinned deformation, whereas condensate/gas discoveries seem to be linked to thick-skinned deformation. Doing it this way, he had arrived at a quantitative and predictive model explaining the variation in observed reservoir fluids in a much faster and yet scientifically sound way.
Eye-opening
When Martin saw Lukasz’s presentation, he saw someone proposing a fresh approach to petroleum system analysis. “It opened my eyes,” Martin says. “I had just left Schlumberger after ten years, where we always pushed for the classical bottom-up simulations as being the only solution. I picked it up immediately and saw the potential of this approach to bring oil versus gas predictions into the very heart of prospect assessment, and with that decision making.”
“Standard prospect assessments deal very poorly with fluids,” adds Lukasz. “You are expected to know if your prospect holds oil, or gas, or both, and the respective column heights. I saw people coming up with far too optimistic scenarios, some of which were physically not possible. Bottom-up basin modelling is very limited in that perspective. Top-down PSA fills that gap between petroleum systems and prospect assessment.”
Developing ideas
Coming back from the Hedberg conference, Martin started developing the concept further. “Quickly surpassing the capabilities of spreadsheets, I started to learn to code.”
Within months, Martin created 20,000 lines of code that performed a “source to trap” probabilistic risk and volume assessment. He then showed his prototype to colleagues and friends. “There was no ambition to make it a real product initially – I just did it by passion,” he adds. But without being aware at the time, Martin had set the foundation for Ariane, a new prospect assessment software.
Lukasz was one of the early adopters and supporters of the software. He worked for Australia-based Santos, where he was involved in basin modelling for petroleum systems and carbon storage projects. When he saw early versions of Ariane, he was impressed and encouraged Martin to turn Ariane into commercial software.
A team effort
But Martin could not do this alone. He was joined by Ben Kurtenbach, who led the development of Schlumberger’s basin modelling software, and Ian Bryant, who did all the strategic acquisitions for Schlumberger’s exploration software portfolio. Together, they founded Germany-based ArianeLogiX.
…it’s not about bottom-up versus top-down PSA. Both have their place in the workflows. The type of project determines whether you choose one or the other. Ideally, bottom-up meets top-down; this is where you have the greatest confidence
Today, five years later, and with the assistance of advisors such as Lukasz, Andrew Murray, Jan de Jager and other very experienced E&P professionals, Ariane is a prospect assessment platform for oil and gas, carbon storage and natural hydrogen which has been adopted by major international E&P companies.
“Ariane has gone a long way since its inception at the Hedberg conference,” Martin reminisces, “and despite the fact that we have added many modules, fluids are still at the heart of it.”
Still a lot left to explore
“When I left Santos last year,” Lukasz says, “I did not need to think long about the name of my own consultancy business – Top Down Petroleum Systems.” In that capacity, he continues working with Martin on the development of Ariane, whilst also working closely with Andrew Murray on other projects.
“Don’t get me wrong, it’s not about bottom-up versus top-down PSA. Both have their place in the workflows. The type of project determines whether you choose one or the other. Ideally, bottom-up meets top down; this is where you have the greatest confidence.”
“We link the various PSA approaches to quantitative and probabilistic prospect assessment and solid decision making,” concludes Martin. “There is still a lot to explore, also beyond hydrocarbons.”
