The Nation faces simultaneous challenges from increasing demand for energy coupled with depletion of conventional oil and gas resources. It is expected that the advanced research described in this proposal will lead to sustainable, safer, environmentally clean and more efficient unconventional oil resource recovery techniques. These attributes will be critical to the economy, environment, and security of the United States in the 21st century.
This research proposal brings together random field theory and finite element methods, also known as the Random Finite Element Method RFEM, which will be developed and applied to the unique geotechnical conditions encountered in the unconventional oil resource recovery industry. The industrial partners at Shell have developed advanced deterministic modeling technologies for exploration and production of unconventional oil resources such as heavy oils and oil shale. This proposal enables Shell to work with academic collaborators at the Colorado School of Mines to include advanced probabilistic based numerical simulation methods into their modeling capabilities. In addition, the practical applications and data made available by the industrial partners will greatly enhance the usefulness of software developed predominantly in an academic environment.
This collaborative project will improve industry-university research linkage in the design and implementation of unconventional oil resource recovery techniques. The aim is to set a high industry standard for unconventional oil resources extraction which will undoubtedly be under close public scrutiny due to the important environmental implications. It is also anticipated that this research will lead to an understanding and recognition of the importance of risk and reliability methodologies among the public, including engineers of the industrial partner.
Developments made in this research will also lead to improved understanding and implementation of risk and reliability methodologies into more routine geotechnical design.
This project was focused on the development of probabilistic analysis tools directed at geomechanical applications, with particular focus on unconventional hydrocarbon resources such as oil shales and tight gas formations. The computational developments ranged from First Order Reliability Methods (FORM) to more computationally intensive Random Finite Element Methods (RFEM). All the software is available to the General Public through the P-I's home page. For example: 1) A FORM analysis of wellbore stability is available at http://inside.mines.edu/~vgriffit/wellbore as shown in Figure 1. This analysis enables the user to predict the probability of wellbore instability based on probabilistic input (rock strength, in-situ stresses etc.) 2) The RFEM developments for a wide range of geomechanical applications can be downloaded from www.mines.edu/~vgriffit/rfem as shown in Figure 2. A typical simulation from an RFEM analysis of oil shale following heating, hydrocarbon removal and subsequent subsidence and settlement is shown in Figure 3. Stresses caused by such movements may result in damage to the cap rock seal. The analyses enable probabilistic estimates to be made relating to this type of damage. In addition to the probabilistic tools developed for petroleum geomechancis applications, the project has also contributed to knowledge in the areas of parallel processing of pre-conditioners and large systems of equations, improved 3D mesh generation and graphical visualization using ParaView software, improved understanding of load and resistance factors and thei relationship to target reliability levels. Broader impacts are potentially far-reaching. Due to the inherent variability of geomaterials typical in oil-shale deposits as shown in Figure 4, combined with a shortage of detailed knowledge of the site, probabilistic methods offer one of the few ways forward for scientific predictions. The research performed in this project has been reported in several publications in journals and conferences. Under the PI's supervision, two post-docs (Chinese and Greek), three grad students (2 American, 1 Korean) and 4 REU (3 American, 1 Korean) students have been involved in the project. Three of the REU students (one female) have since graduated and are either already in, or actively considering Grad School. The research project has also provided materials for short courses offered by the PI for practitioners in Risk Assessment in Geotechnical Engineering. These courses have been offered under the auspices of a number of professional organisations including the American Society of Civil Engineers.