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Multi-Scale Fluid Flow in DYNamically FRACtured Porous Reservoir

Periodic Reporting for period 2 - MSFF-DYN-FRAC-PR (Multi-Scale Fluid Flow in DYNamically FRACtured Porous Reservoir)

Reporting period: 2017-01-01 to 2018-12-31

In order to solve the current energy crises there are a couple of options. In this project we consider two of them: better use of current oil and gas reservoirs and the underground storage of CO2 in empty oil/gas reservoirs. In both applications there are a number of challenges. We will describe these challenges in the next paragraphs.

It is well known that in current oil reservoirs only 20-30% of the oil and gas is exploited. The remainder of the content can not be obtained with standard techniques. In order to obtain also the remaining part, Enhanced Oil Recovery methods are used. One of them is the fracking of the reservoir. However in this technique problems occur: there can be a significant increase in the costs, the surrounding environment can be damaged (including contamination of ground water, risks to air quality etc.), and dangerous gases can escape.

With respect to CO2 storage, it is important to know that CO2 has a higher density than air. This implies that if CO2 is leaking from the reservoir into the atmosphere the air in the neighborhood of the CO2 storage is replaced by CO2. This is very very dangerous because without air both humans and animals will die in a couple of minutes. This danger was one of the reasons that an experiment of CO2 storage in the Dutch city of Barendrecht has to be stopped because the population of the city was afraid of the phenomenon and organized a big protest such that the experiment is canceled.

In this project the aim is to help the oil and gas industry, government and the population by increasing our knowledge of porous media flow when the reservoir contain many fractures. The current knowledge (physics, mathematics and computer science) is able to understand oil flow in reservoirs with a small number of large fractures. However we are not able yet to simulate the flow of fluids in a fractured reservoir (including many small fractures). In order to solve this problem a couple of scientific domains have to be developed.

During the project a literature study of the newest mesh free methods has been done. After that also the most modern iterative methods for solving a large set of (non) linear equations have been studied. The results of these studies have been partially published in progress reports. A start has been made to investigate the mesh free methods. The aim was to presents this at the ECMOR 2018 XVI conference in Barcelona. However due to a slow progress of the PhD student we miss the deadline to deliver the proceedings, so we were not able to attend this conference and present our results.
From the beginning of the project the following work has been done:

- A new mathematical model based on mesh free methods has been developed. This model will be used to obtain solutions that can be used in engineering and numerical code verification.

- Extended thermodynamics is developed in order to describe the connections between the variables that characterize the dynamically fractured reservoirs.

- We started the implementation of the extended irreversible thermodynamics theory in a computational framework. The matlab implementation in combination with the MRST package is ready for use.

- The literature study for extreme scale solvers has started at the end of 2016, and has been finished in June 2017.

- During the stay of Owen Clark at Schlumberger (July-December 2017) discussions and research has taken place to see what are suitable solvers to be included in INTERSECT and what are good benchmark problems for the problems considered by Schlumberger. Due to slow progress the report to describe this research has not been finished.

In order to tackle this important problem we have formed a consortium of the following partners:

- Delft University of Technology (TU Delft Institute of Computational Science and Engineering) This is a world class University (and Institute) in this field. A long time collaboration with Stanford and Shell oil industry has lead that knowledge on this subject is mostly concentrated in these institutes. Many world class iterative methods have been developed (and are developed) in our institute.

- Schlumberger (Abingdon Technology Center (AbTC) and Schlumberger-Doll Research SLB-SDR in Boston, USA) Schlumberger is the world's leading provider of technology for reservoir characterization, drilling, production, and processing to the oil and gas industry.

This is an ideal consortium to solve these important problems for mankind and it is an optimal environment for young people to be trained both in academic research and industrial applications. We know that finding a job after finishing this project is very easy.
The potential impact of the research is very high. The developed method are used to predict in which reservoirs it is safe to use fracking and when not. Another application is the storage of CO2. As mentioned before if the CO2 leaked through a fracture to the atmosphere the population at that spot will die due to the lack of oxygen.

The currently developed mesh free method is already better than the methods known before (see figure). However it appears time consuming to find the solution with current iterative solvers. We have developed new iterative solvers. The results are good. We had presented our work at the SIAM GS 2017 SIAM Conference on Mathematical and Computational Issues in the Geosciences, Germany, 11-14 September 2017. A thorough investigation of the studied meshfree methods for relevant benchmark problems should have led to a presentation at the ECMOR XVI conference: 16th European Conference on the Mathematics of Oil Recovery, 2018 in Barcelona. We had submitted an abstract which has been accepted. However due to slow progress we were not able to submit the full paper before the deadline, so we had not given a presentation at this conference.