Viscous oil recovery and in-situ deasphalting in fractured reservoirs – Part 2: Effect of solvent type and temperature

Sie, Chao-yu; Nguyen, Bradley; Díaz, O. Castellanos; Verlaan, Marco; Nguyen, Quoc P.

doi:10.1016/j.fuel.2019.03.044

Cited by 16 publications

(6 citation statements)

References 38 publications

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“…The dominant bitumen recovery methods are surface mining and in situ recovery (e.g., cyclic steam stimulation or steam-assisted gravity drainage, SAGD), with mining operations accounting for over 50% of the bitumen extracted in Alberta. Some current and proposed bitumen recovery processes use solvent to reduce the density and viscosity of the bitumen; for example, solvent-assisted SAGD, paraffinic froth treatment in mined oil sand processing, − nonaqueous extraction of bitumen from mined oil sand, − and partial deasphalting processes. − Many of these processes involve precipitation, aggregation, and settling of asphaltenes from solvent-diluted bitumen, sometimes along with mineral solids and water droplets. In these processes, the solvent acts as a precipitant.…”

Section: Introductionmentioning

confidence: 99%

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

et al. 2019

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The settling rate of asphaltene aggregates is a key design parameter for partial deasphalting processes, and yet few data and models are available for these systems. The settling rates of asphaltene aggregates were measured in two Western Canadian bitumens diluted with n-heptane or n-pentane at 21 °C and atmospheric pressure. The density and viscosity of the mixtures, the size distributions of the aggregates, and the fractal dimensions of the aggregates were also measured. The asphaltene aggregates settled as a zone, that is, all aggregates settled at the same rate. The settling rates increased with increasing n-alkane content, reached a maximum at approximately 75 wt % n-alkane and then decreased at higher dilutions. The maximum settling rate corresponded to the maximum aggregate diameter and fractal dimension. The maximum settling rate in n-pentane diluted bitumen was 2 orders of magnitude greater than in the same bitumen diluted with n-heptane. The difference was attributed to the lower density and viscosity of the medium, larger aggregates, and higher fractal dimensions in n-pentane versus n-heptane. The settling rates were modeled with Stokes' law modified to include the fractal dimension of the aggregates. Since zone settling was observed, the settling rate was determined from a single average diameter applied to all of the aggregates. The Sauter mean diameter was found to provide the most consistent results for the diluted bitumen systems in this study. No other form of hindering was required to match the data. The model matched the measured settling rates to within 20% of the maximum settling rate. The model is sensitive to the fractal dimension of the aggregates, and therefore precise determination of the fractal dimension is critical or it must be tuned to match the settling data.

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Section: Introductionmentioning

confidence: 99%

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

et al. 2019

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“…These solvents are only partially miscible in bitumen and can precipitate asphaltenes above a threshold solvent content. Asphaltene precipitation leads to an upgraded product oil and can inhibit both the gravity drainage and mass-transfer mechanisms. − Condensing solvent processes have not yet been implemented on a commercial scale, but an N-Solv pilot test was conducted on the Dover lease from 2014 to 2017 and showed promising bitumen production rates and high solvent recovery. More than 125,000 bbl of 8° to 14° API-upgraded bitumen was produced, and 80% of solvent injected was recovered.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Solvent-Assisted Gravity Drainage in a Packed Hele-Shaw Cell with Liquid Toluene over Bitumen

2022

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The condensing solvent process is a heavy oil (or bitumen) recovery method where the injected vapor solvent condenses when it contacts the colder bitumen and the bitumen diffuses into the condensed liquid. The process has been piloted, but field implementation is impeded by the absence of a reliable model to upscale laboratory measurements to the field scale. In order to better understand and represent the mechanisms controlling the process, a glass-bead-packed Hele-Shaw type apparatus was partially filled with bitumen with a sloped interface, and liquid toluene was flowed on top of the bitumen layer at a fixed flow rate. Bitumen and solvent recoveries were measured over time, and the change in the bitumen profile was tracked with a camera. The key mechanisms of the process were verified to be the diffusion of bitumen into solvent through convective mass transfer and convective flow of the resulting mixture in the drainage layer by gravity. An approximate analytical solution was derived for dilute conditions (high solvent flow rates) and used to identify the transition from a finite to a semi-infinite mass transfer boundary condition in the drainage layer. A numerical model was fitted to the experimental data, and a correlation was established for the convective mass transfer coefficient of bitumen into the solvent in porous media. The correlation has only one adjustable parameter which was constant for steady-state mass transfer in the semi-infinite acting regime.

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“…Since its conception, much effort had been expended to understand and model SAGD, while many innovations have been made to improve the process. Much research has been conducted on the use of solvents for heavy oils and SAGD (Haghighat and Maini 2013;Sie et al 2018Sie et al , 2019. Recently, however, studies done on non-solvent chemistries that possess potential for improving SAGD performance have become available.…”

Section: Introductionmentioning

confidence: 99%

Organic bases as additives for steam-assisted gravity drainage

Brame

Mukherjee

et al. 2019

Pet. Sci.

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Steam-assisted gravity drainage (SAGD) is a mature technology for bitumen recovery from oil sands. However, it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen. The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives. The research is approached from three focus areas that supplement and guide each other: characterization tests, sand-pack floods, and computational simulation. A number of key mechanisms for enhancing oil recovery were identified, high-temperature additive characterization tests were developed, and promising alkalis were tested in porous media. Simulation was employed to history-match sandpack flood production data, in order to demonstrate the effect of an additive on the oil-water relative permeability. Based on these results, it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil-water interfacial tension (IFT) by increasing the pH of the system. These organic bases favorably modify the interfacial energies between the immiscible oil-water phases and enable them to flow easily through the porous media during production. Sand-pack flood tests have successfully demonstrated a 10%-15% improvement in bitumen recovery, over baseline, in the presence of IFT-reducing additives. Simulation results further showed that an IFT reduction had a positive impact on SAGD performance. This work demonstrates the potential of organic bases to improve not only SAGD, but other steam injection processes. Furthermore, a number of experimental methods were developed, tried, and tested during the course of this work. Keywords Heavy oil • Steam flood • Low interfacial tension • Wettability • Enhanced oil recovery • Organic bases List of symbols k rw Water relative permeability at S w k row Oil relative permeability at S w k rwro Water relative permeability at residual oil k rocw Oil relative permeability at connate water S w Water saturation S wc Connate water saturation S orw Residual oil saturation in the presence of water Z w Water Corey exponent Z ow Oil Corey exponent

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Viscous oil recovery and in-situ deasphalting in fractured reservoirs – Part 2: Effect of solvent type and temperature

Cited by 16 publications

References 38 publications

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

Settling of Asphaltene Aggregates inn-Alkane Diluted Bitumen

Investigation of Solvent-Assisted Gravity Drainage in a Packed Hele-Shaw Cell with Liquid Toluene over Bitumen

Organic bases as additives for steam-assisted gravity drainage

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