Oil mobilisation by subcritical water processing

Abstract

As water approaches the critical point, the dielectric constant lowers enabling solution of heavy oil components. Simultaneously, enhanced water dissociation enhances cracking to lighter fractions. We evaluated this effect for three heavy oils concentrating on the effect of processing on feed viscosity. Reductions of up to 90 % were observed and these could be achieved in a few hours. Although more applicable to surface processing of oil sands in the short term, ultimately this technique could also be applied to immature oils for in situ processing and recovery. This may already be happening in some steamassisted gravity drainage scenarios. In situ application would be limited to reservoirs where formation pressure is higher than the pressure required to generate these subcritical effects.

Enhanced viscosity reduction in heavy oils by subcritical water

“…10 -14 . The resulting higher H?/OHconcentration enhances cracking potential (Ryan et al 1997;Patrick et al 2001;Akiya and Savage 2002;Golombok and Ineke 2013). By contrast, supercritical water relies solely on its increased thermal cracking potential (Ogunsola and Berkowitz 1995;Kamimura et al 1998;Deng et al 2011;Park and Son 2011;Deng et al 2012;Golombok and Ineke 2013).…”

“…SCW has several potential applications, including extracting oil from oil shale lumps (Deng et al 2011), sulphur removal (Kamimura et al 1998;Park and Son 2011), tar sands (Park and Son 2011) and the cracking of heavy hydrocarbons into lighter fractions (Duan et al 2013;Golombok and Ineke 2013), thereby reducing the viscosity. The use of catalysts to enhance near critical effects has recently been extensively reviewed (Tumanyan et al 2015).…”

Investigation of Asphaltene under Subcritical Water Treatment

“…Thus subcritical water can convert AS and coke into valuable MA. Golombak and Ineke [27] in 2013 disclosed that the hot water can pyrolytically crack the long molecular weight structures. Literature revealed that the hydrothermal reaction mechanism depends on water density: the reaction is controlled by the ionic reaction mechanism at high water density and low temperature; whereas the free radical reaction mechanism is prevalent at low water density and high temperature [28]- [30].…”

“…The respective subscripts (l) and (aq) refer to the hydrocarbon components present as pure water-insoluble liquid as found at ambient condition and dissolved in water under subcritical conditions. The ions, [H + ] and [OH -], are the respective concentrations of hydrogen and hydroxide ions arising from dissociation of water as [27]:…”

Comparison Study of Heptylbenzene and Hexylbenzene Decomposition under Supercritical Water

“…Golombak and Ineke [25] in 2013 disclosed that the hot water can pyrolytically crack the long molecular weight hydrocarbon structures. Literature review revealed that the hydrothermal reaction mechanism depends on water density: the reaction is controlled by the ionic reaction mechanism at high water density and low temperature; whereas the free radical reaction mechanism is prevalent at low water density and high temperature [26], [27].…”