Sherlock Holmes and the Adventure of the Reservoir Rock

Where can we find hydrocarbons such as natural gas? And how? The work of Cameron Sheya revolves around these questions. As an exploration geoscientist at OMV, he is responsible for identifying, analyzing and maturing opportunities that may contain potential hydrocarbons. As part of a multi-disciplinary team, he investigates a wide range of factors to provide the best assessment of the subsurface in the search for economically feasible resources like crude oil and natural gas. This then serves as the scientific rationale for future business decisions. 

We feel a little like Sherlock Holmes,” says Cameron. “Our work is similar to assembling a puzzle. The overall picture isn’t clear until we have a good overview of all the data, mixed with plenty of patience.
Cameron Sheya, Exploration Geoscientist at OMV Norge

A dozen or more experts from disciplines like geoscience, geophysics, chemistry, engineering, and economics, to name but a few, work closely together to solve this complex puzzle. It can sometimes take a decade from the initial analysis before actual production can begin. In well-explored areas like the Vienna Basin in Austria, this process can be much faster, sometimes needing as little as six months from drilling the appraisal well to actual production. 

Seismic data - the clue to solve the riddle

The daily work of exploration geoscientists includes the analysis of an array of technical data and interpretations. One example is seismic data, which provides an indirect image of the subsurface. It involves sending harmless vibrations below the earth in order to paint a kind of acoustic picture. Now common throughout the industry, it wasn’t until the 1940s that seismic data was advanced enough to be implemented on a large scale. “In the past, people picked drilling locations in areas where they had a reasonable suspicion that gas or oil could be found based upon the surface geology, among other factors,” Cameron explains. 

With the increase of new and novel datasets and methodologies, it has been possible to carry out more precise interpretations in the subsurface, leading to an increase of discoveries worldwide. Huge datasets are always examined in detail before a drill bit ever touches the ground. Even then, the success rate of exploration wells across the industry is between 20 and 25 percent. Although it may seem low, this range of probability it is understandable considering the technical challenges that nature can present. 

The secret of the subsurface

The prerequisite for future business decisions is expertise on the processes occurring deep in the subsurface. Geoscientists know that specific criteria must be met for natural gas to accumulate: it needs a source (precursor of hydrocarbons), a reservoir rock (the place where the hydrocarbons are stored), a trap (where the gas is contained) and a seal that ensures that the gas accumulation does not escape. 

Another factor analyzed is migration, i.e. how the hydrocarbons may have travelled from the source rock (where hydrocarbons are generated) into the reservoir rock. All of these parameters must be present and correct to have a good chance of hydrocarbon accumulation. Moreover, while it is essential to narrow down the area that may contain hydrocarbons, it is also important to understand the quantity and quality of the potential resources available. 

If the exploration well proves successful and is also economically profitable, the field can then move on to the appraisal and production phase. When it comes to production itself, it is crucial to use reliable technologies in order to recover as much gas as possible from the field. “OMV happens to be one of the best in recovery rates, especially from (super) mature fields” says Cameron. Here, the expertise of the geoscientists is needed yet again, every step of the way. 

Technological advances: like an AI Watson to Sherlock Holmes knowledge

Returning to geologic interpretation and assessment: with the improvement of computing power, the experts are able to analyze larger datasets as data becomes more complex. Just as modern forensics underwent a technological revolution with DNA analysis which led to a higher understanding of crime evidence, the world of oil and gas exploration is beginning to be further shaped by machine learning and artificial intelligence which are being integrated more and more into the processes and workflows.

Methods are constantly improving, and knowledge of certain regions is growing in parallel. “Comparing the data available in past decades to the present situation is somewhat like comparing an old, blurry black-and-white photo to a high-resolution gigapixel image,” says Cameron. But despite the technological advances, the experience of the experts will always play an invaluable role. “Data only makes up one half; the other half is knowledge,” he adds.