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Repsol and digital rocks

Tuesday, March 21, 2017

Oil and gas operator Repsol is developing 'digital rocks' - digital models of rocks - to better understand the reservoirs. By Carlos Santos, Repsol Technology Center researcher.

During the exploration and production process, oil and gas companies have to consider a great number of unknowns in order to determine the reservoirs' potential and economic viability, which will help to optimise the production plan for each exploration project.

Some of the most critical areas on which to have as much information as possible are the properties of the subsoil, the properties of the rock, as well as the interactions occurring within its structure.

For almost 15 years, Repsol scientists have been at the forefront of developing exploration technology at the company's own R&I centre, the Repsol Technology Centre.

Through a number of different research projects, Repsol scientists have developed the necessary expertise to offer innovative solutions in all areas of the energy process, from the exploration of hydrocarbons to their transformation into products with greater added value for society. The aim is to create energy systems that are safer, more efficient and environmentally sustainable.

The processing and analysing of large sets of data is one of the areas on which Repsol's scientists have been focussing for many years.

One of those technologies is the Sherlock Project, which was launched in 2009 with the intention of reducing geological risk and raising the exploration success rate.

This operational area comprises of several related, but very different disciplines: the Geology Laboratory, which mostly contains techniques for geological classification; the Petrophysics Laboratory and the Fluids Laboratory, which combines techniques for fluids classification and flow assurance.

By taking different samples of rocks from various geographic locations, Repsol scientists are able to learn everything possible from the samples, and to determine when, how and where the oil was formed in order to understand certain migration patterns.

Sherlock enables Repsol to develop and implement a methodology based on petrographic microscopy and high-resolution geochemical analysis techniques, which is necessary for characterising the different elements of oil systems such as reservoir, seal, source rock and migration paths. Ultimately, this reduces geological risk and increases the exploration success rate.

Repsol's researchers have been eager to learn more about the properties of rocks, including porosity and permeability, as well as the interaction between the rock and fluids within it, in order to determine the profitability of the reservoir in question, and find out the best way for a potential oil and gas extraction. Digitalisation can simplify this task and help to analyse rocks anywhere in the world, without having to be transported to the closest research facility.

In January 2016, after several years of research and further development of Sherlock, Repsol successfully launched Sherlock II, which combines data science and physics as well as numerical methods in order to create digital representations of subsoil rocks. With researchers trying to obtain trustworthy information without the need to extract hundreds of rocks, they turned their attention towards rock fragments.

How it works

By using very high-resolution imaging, petrophysics can reconstruct the properties of reservoir rocks.

By taking 3-dimensional x-rays, Sherlock II is able to create a 3D model, or a 'digital rock', in a virtual laboratory. This cuts down decision time and reduces geological uncertainty in the exploration and production of hydrocarbons.

In doing so, Sherlock II saves Repsol a significant amount of time as experiments that used to take three months can now be done ion three weeks, and on a much cheaper scale. Another benefit of Sherlock is size and storage - transforming stones into data also makes it easier to store than physical stones.

With the help of Sherlock II, rock fragments can be scanned with a resolution that is between a thousand and a million times higher than CAT scans used in medicine. The data is then sent to the Repsol Technology Center in Madrid, where it is analysed virtually by the supercomputer which is also able to create an exact representation of the rock as a 3D model.

Sherlock II's software is based on the use of numerical methods, a type of mathematics that translates the laws of physics into a numerical language. The computer can then use this data to translate the images into petrophysical properties.


Sherlock II also aims to improve knowledge of unconventional reservoirs or those with more complex geological properties, where a large portion of yet unexplored resources reside. The physical processes of these reservoirs are much more complex than traditional fields. For example, rock types where the connections between the pores are key to understanding how to extract hydrocarbons contained within, are of nanometric scale.

Repsol researchers use an electron microscope, ion beams and electron scan in order to capture these nanoscale structures, allowing them take images dozens of nanometres thick. These are superimposed like slices of a cheese until they build the 3D image.

Sherlock II has generated three patents and the technology has been applied progressively. In addition, Repsol has been able to generate operational savings through continuous development at various exploration projects and field developments through several pilot projects. This has helped Repsol to fund the entire research project within a short period of time.

Exploration success

One of the main advantages of Sherlock II is its ability to reduce uncertainty, thus speeding up the exploration process and increasing the knowledge of the reservoir. Ultimately, this has increased the exploratory success rate.

Repsol's investment in digital petrophysics has turned the Repsol Technology Center into a pioneer at the European level in this field. During the development phase, the research had been tested with good results in pilots in South America and the Caribbean. During the testing, up to 70% of the operating costs were saved, compared to using alternative commercial technologies.

Processing large sets of data is one of the areas in which Repsol is becoming increasingly active as this can improve the evaluation of exploration projects, speed up the decision making process and therefore reduce exploration costs. Repsol remains committed to continuing the development of technological solutions, enabling scientists and researchers to make better decisions about future reservoirs by obtaining the same amount of oil with fewer wells and less disturbance to the environment.

Associated Companies
» Repsol S.A.
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