Mathematicians from the University of Leicester and geologists from Weatherford, which provides technologies and services to the oil and gas industry, have developed a new software tool for visualising the structure of the Earth deep underground.
Deep down into the Earth geologists send probes to uncover secrets that have been hidden for millions or billions of years.
Mineral and organic deposits kilometres under the crust have provided the raw materials for the development of human society for hundreds of years. As time goes on, and the upper layers lose their treasure, the ability to measure and visualise what is deeper becomes more important.
Mathematical modelling has become a fundamental tool for creating plausible explanations for that which is hidden, and industry is becoming ever more aware of its extraordinary potential for illuminating that which is dark to us.
The pseudo-outcrop visualisation of borehole images created by the software transforms data into a solid 3D volume which can be sliced to simulate how rocks might look in a natural outcrop setting.
The result is more immediately interpretable by the non-expert because it more closely honours the actual shapes of geological features. Moreover, the steps used to create the 3D volume also allow individual sets of dips to be isolated from one another in the commonplace situation of multiple dip patterns existing in the same volume.
Professor Alexander Gorban, leading the University of Leicester team from the Department of Mathematics, including Professor Jeremy Levesley and Dr Evgeny Mirkes, said: “It is great and stimulating for our academics and students when our research meets practical industrial needs!
“Collaboration with Weatherford has helped us to develop our research in many areas: in data visualisation, new numerical methods for calculating of multi-phase flows in complex porous media, new methods for remote identification of the position, size and shape of corrosion-related defects in steel, and in many other directions and projects.
“We hope with this project that we will make a difference to Weatherford’s service delivery, making them the best in the sector. This is one step on the way to a more automated way of helping practitioners integrate diverse data into their decision making.”
One of the interpretational challenges facing researchers is translating the shapes observed in the circumferential scans to the shapes as they exist in the rock itself i.e. in the Earth’s frame of reference.
Dipping planar geological boundaries, for example, appear in the circumferential scans as sinusoids when the image is unwrapped for display on a computer monitor, and although expert image interpreters are able to make the mental leap between reference frames, non-experts often need help.
Data acquired along the length of a borehole during or shortly after drilling provide information about the physical and chemical properties of the rocks through which it is drilled.
As well as allowing the materials of interest to be identified, data also provides clues to nearby geological structures which can become the targets for future drilling, and the most useful data for this application comes from high resolution borehole image logs.
The software can create high-resolution scans of the borehole wall, commonly made using arrays of electrodes which respond to the electrical resistivity of the rock.
The paper ‘Pseudo-Outcrop Visualization of Borehole Images and Core Scans" is published in Mathematical Geosciences, the flagship journal of the International Association for Mathematical Geosciences.
A joint patent application is filled.