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Multiphase relative permeability is a key parameter in reservoir simulation. Typically, end-point based correlations are employed in order to obtain such curves for reservoir simulation purposes. However, those correlations are not capable of capturing micro-scale physical phenomenon which can significantly affect flow pattern at larger scales. Consequently, it is necessary to obtain a scale-up methodology in order to transfer the micro-scale physics to reservoir-scale. The objective of this research is developing a scale up procedure which can be applied to multi-phase flow properties obtained by micro-scale flow simulation to compute the equivalent macro-scale and core-scale flow properties having the micro-scale flow properties. Two different sets of media are employed: media representing unconsolidated oil sands and media based on experimental data obtained from the Mesaverde formation located in the Poweder River Basin. The former is used for validating the scale up methodology since not all the required information is available in the experimental data set. Pore scale network modelling is used for calculating micro-scale multi-phase flow properties such as porosity, and absolute and relative permeability. Then the generated subsegments are populated in space to reconstruct the macro scale medium. Flow properties of such medium are then obtained by network modelling and the proposed scale-up methodology and the results are compared. Furthermore, macro-scale media are distributed in space in layers and stacks of increasing and decreasing permeability to form a core-level medium. Single and multi-phase flow properties are then calculated by applying a pressure drop across the core. Permeability and relative permeability curves are calculated using the combination of mass balance, equation of state, and Darcy equation assuming steady-state flow while capillary pressure curve is obtained using the modified Leverett-J function procedure used in micro-to-macro scale up section. Results show good agreement between the expected and calculated properties for both unconsolidated and consolidated media. Finally, physical behavior observed at micro and macro scale is transferred to the core scale.
DTS/DAS applications provide key advantages in surveillance and better understanding of both unconventional and thermal operations in terms of key attributes including but not limited to conformance, wellbore integrity in better spatial and temporal terms. This study investigates the effects of CO2 and Naptha in enhancing the steamflood process while incremental benefits are achieved through improved monitoring of the steamflood injection process using DTS/DAS applications.
A full-physics simulator is used to model the process. The technical as well as economic details of deployment of DTS/DAS as well as the steam-additive process are outlined in detail. Sensitivity study carried out on the model indicates the key attributes along with their significance. Athabasca bitumen properties are used. CO2 additive increases the steam chamber size but lowers the steam temperature while naptha/CO2 additives lower the viscosity, thus optimization study carried out the optimum operating levels of the additives not only in physical production/injection terms but also in terms of economics.
The results indicate better reservoir management with DTS/DAS applications compared to the base case and injection can be monitored and adjusted better with such tools. The objective function built with economic parameters helped to maximize the NPV for the project, providing a more realistic perspective on the projects. DTS/DAS applications prove useful not only in terms of production performance but also in terms of economics. Physical properties of CO2 and naptha indicate that the two have different dominant modes of improving recovery of steam only injection. CO2 increases the extent of the steam chamber while lowering the steam temperature significantly.
This study approaches the delicate process of additive use in steam processes while coupling the additional benefits of use of DTS/DAS applications in optimizing the recovery and the economics outlining the key attributes and the challenges and best practices in operations serving as a thorough reference for future applications.
Mohammadmoradi, Peyman (University of Calgary) | Bashtani, Farzad (University of Calgary) | Goudarzi, Banafsheh (University of Calgary) | Taheri, Saeed (University of Calgary) | Kantzas, Apostolos (University of Calgary)
Due to the computational simplicity and time efficiency, pore network and morphological techniques are two practical approaches for characterization of pore-scale microstructures. The methods are quasi-static and exploit pore space spatial statistics to simulate pore invasions. Here, both procedures are evaluated applying the workflows to pore-level micro-scale subdomains of Sandstone, Carbonate and Shale formations. A statistical approach is also utilized to improve the accuracy of Shale characterization by spatial restoration of fragmentary parts of organic matter. Post-processing results include relative permeability and capillary pressure curves, absolute permeability, formation factor, and thermal connectivity. The results appear to suggest that the accuracy of pore network modeling in the characterization of subdomains of micro-CT images is compromised by the presence of limited number of network elements, ignoring the resistance of pore elements, multi-scale structures, and tight/weak connections represented by an inadequate number of voxels. Pore network extraction negatively affects the accuracy of petrophysical predictions and ignores solid matrix and its thermal and electrical properties. The pore morphological approach accurately reproduces the fluid occupancies, efficiently deals with a variety of rock configurations and resolutions, and preserves connectivity and details of original images having more geometrical features than the pore network modeling. However, it predicts limited step-wised data points and realizations sourcing from its voxel-based nature. In addition, direct simulations confirm that stochastic conditional reconstruction of organic matter inside shale sub-volumes remarkably boosts the pore space connectivity and improves the accuracy of predictions.
Yegane, Mohsen Mirzaie (Sharif University of Technology) | Bashtani, Farzad (PERM Inc) | Tahmasebi, Ali (Digital Core Analysis Laboratory, University of Calgary) | Ayatollahi, Shahab (Petroleum University of Technology) | Al-wahaibi, Yahya Mansoor (Sharif University Of Technology)
The application of the renewable energy sources, especially solar energy, for thermal enhanced oil recovery methods as an economical and environmental valuable technique has received many attractions recently. Concentrated Solar Power systems are capable of producing substantial quantities of steam by means of focused sunlight as the heat source for steam generation. This paper aims to investigate viability of using this innovative technology in fractured reservoirs to generate steam instead of using conventional steam generators.
A synthetic fractured reservoir with properties similar to those of giant carbonate oil reserves in the Middle East was designed by using commercial thermal simulator. The dual porosity model was used to account for differences in matrix and fracture parameters. Different cyclic and continuous steam injection scenarios using combination of both solar energy and fossil-fuel to generate steam were designed. The cyclic scenarios were different in terms of contribution of solar energy in steam generation and in case of 100% solar scenario a small nightly steam injection using fossil-fuel was suggested to prevent flow back into the wellbore.
It was assumed that total amount of injected steam in 10 year time period is the same for all the scenarios regardless of how steam was generated. Simulation results showed that nightly injection of insignificant amount of fossil-fuel-generated-steam in a 100% solar-generated-steam injection process increases the cumulative oil production compared to 100% solar-generated-steam injection system with no nightly injection. Furthermore, there was no significant difference between the final oil recoveries for all the designed cyclic injection scenarios. Although continuous steam injection scenario had the highest final oil recovery among all scenarios, a detailed economical study showed that net present value for 100% solar-generated-steam scenario is the highest. An environmental analysis on all scenarios also indicated significant reduction of CO2 emission into the atmosphere for the latter scenario.
Therefore, hybrid steam generators which utilize solar energy instead of traditional fossil-fuel for steam generation is proposed for Middle East fractured reservoirs where there is abundance of sunshine during day time. The findings illustrate high economic efficiency of solar-generated steam injection and highlight it as a green EOR method.
Application of solar energy compared to conventional gas-burning boilers for steam generation in thermal Enhanced Oil Recovery processes is a newly attended technology, which brings significant benefits to the petroleum industry through environmental and economical aspects. This technique is especially designed for the regions in which gas-burning steam generation is not viable in large scale. The objective of this study is to investigate about viability of using solar energy to generate steam instead of using conventional steam generators in a Venezuelan extra heavy oil reservoir. Limited gas production policy of the Venezuelan government is the major challenge for utilizing gas steam generators for extra heavy oil reservoirs in this country. Besides, the efficient daylight duration, economic and environmental advantages, are the main features to propose solar-generated-steam injection in Venezuelan extra heavy oil reservoirs. In this study, various scenarios of steam injection on Hamaca-Venezuelan heavy oil reservoir-have been investigated using commercial thermal simulator software and the main results of oil production for similar time periods (5 years) are compared. To compensate the energy needed for the steam generators during the night time, dual types steam generators were proposed to utilize solar and fossil energies during day-time and night time respectively. The simulation results for this extra heavy oil reservoir indicated that the oil production was not significantly improved when solar method is used regardless of the amount of the nightly injection of fossil-fuel generated steam for flow back prevention. This finding illustrated high economic efficiency for solar-generated steam injection compared to dual type (solar and fossil-fuel) steam generator method. Furthermore, the results indicated that in typical imposed cyclic steam injections in integrated solar thermal projects, there is no significant difference in oil productions in various scenarios with different pattern and rate of steam injection if the total amount of injected steam is constant. In addition, this study shows the significant reduction of CO2 and Sulfur Oxides emissions if this new technology is implemented. Besides, various scenarios (with and without natural gas backup) were designed for exact day light duration profile in vicinity of the reservoir in order to optimize the oil production as well as accurate economic and environmental evaluation for each scenario.