Fate of Organic Liquid-Crystal Domains during Steam-Assisted Gravity Drainage/Cyclic Steam Stimulation Production of Heavy Oils and Bitumen

Abstract

The fate and impacts of hydrocarbon-based amphotropic liquid-crystal-rich domains (a recently identified material class found in hydrocarbon resources) during production transport and refining are unknown. New materials and process knowledge on this topic will contribute to parsing impacts currently attributed to asphaltenes or other crude oil fractions. In this qualitative work, the fate of liquid-crystal-rich domains in steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) production environments is surveyed, using a combined laboratory and field study. In the laboratory, a fraction of liquidcrystal-rich domains present in Athabasca bitumen is shown to transfer to the water-rich phase under simulated SAGD and CSS conditions and transfer mechanisms are discussed. In the field study, liquid-crystal-rich domain transfer from Peace River and Athabasca bitumen to process water during SAGD production is demonstrated. Transferred liquid-crystal-rich domains are subsequently captured in surface facilities (primary separation, secondary separation, and water treatment processes) and do not impact steam generator operation, under normal operating conditions. Most of the liquid-crystal-rich domains are returned to the hydrocarbon-rich phase during primary separation. Impacts of liquid-crystal-rich domains on hydrocarbon resource transport and refining and SAGD surface facility optimization comprise foci for future study.

Influence of High-Molecular n-Alkane Associates on Rheological Behavior of the Crude Oil Residue

“…However, it is possible to find some studies, , where heavy crude oil rheological behavior differed from the Newtonian flow even in the temperature ranges of 70–90 °C. The supramolecular structures and microscopic and larger phase domains (including liquid crystal domains − ) impact bulk fluid densities, − transport properties (diffusivity and Newtonian and non-Newtonian rheological behaviors) . A similar behavior is true for the most natural bitumen samples. ,, Despite the fact that deviations from the Newtonian behavior of oil residues at 70–90 °C are small, they still indicate the heterogeneity of the studied oil dispersed system and the ongoing destruction of the oil dispersed system structures as a result of shear thinning.…”

“…A stabilizing effect on such emulsions can have such oil components as naphthenic acids, , asphaltenes, and its subfractions. Such like amphiphilic compounds can form liquid crystal layers and domains in crude oil. − Indeed, asphaltene and its subfractions are considered as well-appreciated stabilizers of water-in-oil emulsions due to their active surface that forms asphaltenic films at the oil–water interface. − The asphaltenic films depending on the concentration of dissolved asphaltene particles can be a monolayer or a layer of aggregated asphaltenes with 40–90 nm thick . Aggregated asphaltenes comprise a porous gel-like 3D network with viscoelastic properties.…”

Composition and Formation of Liquid Crystal Domains in Hydrocarbon Resources

“…Liquid crystal domains have also been observed at oil–water interfaces, , where they influence the stability of water-in-oil emulsions . Transfer of liquid crystal domains from Athabasca to a water-rich phase has been demonstrated in steam-assisted gravity drainage (SAGD) facilities and laboratory measurements . Liquid-crystal-like behavior has also been observed in model rag layers associated with a naphthenic froth treatment process for mined Athabasca.…”

“…Naphthenic acids (C n H 2n+z O 2 ), also a common constituent in hydrocarbon resources, assemble cooperatively to form liquid crystal lamellae. 22 As we have already shown that liquid-crystal-rich domains transfer from Athabasca-rich to water-rich phases in both the laboratory and the field, 30 our objective is to isolate and analyze the chemical composition of produced water samples obtained at the outlet of the free water knockout drum at the industrial-scale Nexen Energy ULC Long Lake SAGD Facility. Sufficiently produced water was available from this source to permit the extraction of large enough samples, so that quantitative composition measurements could be made.…”

Treatment Technologies for Organics and Silica Removal in Steam-Assisted Gravity Drainage Produced Water: A Comprehensive Review

“…Also, there is a trend showing that bitumen production by in situ technology will increase faster than that by surface mining by 2029 . Steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) are two primary in situ thermal recovery processes used for bitumen production . In the SAGD process, the bitumen is extracted through three typical processes with a pair of parallel horizontal wells: (i) Hot steam is injected from the upper well to form a steam chamber so that the bitumen can be heated up, and its viscosity can be reduced.…”