Cyclic Solvent Injection (CSI) and Cyclic In-situ Upgrading Technology (CISUT) in Tight Oil Reservoirs
Date
2020-09-04
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Abstract
Due to increasing energy demand and fast depletion of conventional oil resources, a strong interest exists in unconventional oil production; namely, light oil from shales and extra-heavy oil from naturally fractured carbonates. The heterogeneous nature of these class of reservoirs, along with their low matrix permeability and porosity, have been known as major constraints for implementing conventional enhanced oil recovery (EOR) techniques. Huff and puff mode or cyclic injection has been recognized as one of the promising recovery techniques in which the injection and production occur in a single well. In this dissertation, we present results from comprehensive simulation of cyclic CO2 injection(CCI) in Bakken ultra-tight oil reservoir and both experimental and numerical modeling of cyclic gas injection in Ayatsil extra-heavy oil carbonate. For the first time, application of extra heavy oil in situ upgrading using ultra dispersed catalysts is investigated in a cyclic mode. Numerical simulations have been paired with the experimental design method in order to identify the parameters that could control oil recovery, CO2 utilization, and CO2 retention factors of the cyclic CO2-EOR process. Impacts of rock heterogeneity and dependency of relative permeability on saturation history during CCI in various operational constraints, are studied. Through conducting sets of huff’n’puff experiments, effective molecular-diffusion coefficient of gases in Ayatsil oil is determined based on pressure-decay theory for CO2-oil, ethane-oil, CO2-C2-oil and mixture CO2-C2-C3-oil at constant temperature. In extra-heavy oil, hydrogen deficiency and high carbon content, sulfur, and metals necessitate upgrading procedure to obtain proper feedstock for a normal refining. In this study, the feasibility of nano-catalyst in-situ upgrading technology (ISUT) in a cyclic mode is investigated for carbonate saturated with Ayatsil oil. In setup, hydrogen and catalyst dispersed in vacuum residue are co-injected to be transferred through the fracture medium. After the catalysts are located in the matrix oil in place, the catalytic reactions and hydro-conversion process take place. Useful analytical methods are utilized to prove the effectiveness of the proposed cyclic in-situ upgrading in heavy oil. Our numerical simulations are capable of regenerating our laboratory results by capturing combination of hydroprocessing reactions, heat transfer and mass transfer phenomena.
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Keywords
Enhanced oil recovery, Ultra-tight reservoirs, Heterogeneity, Permeability Hysteresis, Cyclic solvent injection, In-situ upgrading technology, Nano-catalyst, Hydroprocessing
Citation
Assef, Y. (2020). Cyclic Solvent Injection (CSI) and Cyclic In-situ Upgrading Technology (CISUT) in Tight Oil Reservoirs (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.