Gravity Segregated Flow in Surfactant Flooding

Lohne, Arild; Purwanto, Eko Yudhi; Fjelde, Ingebret

doi:10.2118/154495-ms

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…Study showed that the residual oil saturation ranged between 15% for the mixed-wet samples and nearly 50% for the strongly water-wet samples [60], and it was also shown that weakly water-wet and mixed-wet water samples produced more oil, although at slower rate during spontaneous imbibition than strong water-wet samples. Recent studies showed that positive effect of decreasing IFT was larger in mixed-wet formations than in water-wet formations [61]. Spontaneous imbibition tests at water-wet and mixed-wet conditions indicated that the spontaneous imbibition rate at mixed-wet conditions was slower and the oil production was much smaller than at water-wet [44].…”

Section: Wettability Effectsmentioning

confidence: 95%

Proper Use of Capillary Number in Chemical Flooding

Guo

Wang

et al. 2017

Journal of Chemistry

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Capillary number theory is very important for chemical flooding enhanced oil recovery. The difference between microscopic capillary number and the microscopic one is easy to confuse. After decades of development, great progress has been made in capillary number theory and it has important but sometimes incorrect application in EOR. The capillary number theory was based on capillary tube bundles and Darcy’s law hypothesis, and this should always be kept in mind when used in chemical flooding EOR. The flow in low permeability porous media often shows obvious non-Darcy effects, which is beyond Darcy’s law. Experiments data from ASP flooding and SP flooding showed that remaining oil saturation was not always decreasing as capillary number kept on increasing. Relative permeability was proved function of capillary number; its rate dependence was affected by capillary end effects. The mobility control should be given priority rather than lowering IFT. The displacement efficiency was not increased as displacement velocity increased as expected in heavy oil chemical flooding. Largest capillary number does not always make highest recovery in chemical flooding in heterogeneous reservoir. Misuse of CDC in EOR included the ignorance of mobility ratio, Darcy linear flow hypothesis, difference between microscopic capillary number and the microscopic one, and heterogeneity caused flow regime alteration. Displacement of continuous oil or remobilization of discontinuous oil was quite different.

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Section: Wettability Effectsmentioning

confidence: 95%

Proper Use of Capillary Number in Chemical Flooding

Guo

Wang

et al. 2017

Journal of Chemistry

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“…Study showed that the residual oil saturation ranged between 15% for the mixed wet samples to nearly 50% for the strongly water-wet samples (Humphry et al, 2013), and it was also shown that weakly water and mixed water samples produced SPE-175172-MS more oil, although at slower rate during spontaneous imbibition than strong water wet samples. Recent studies showed that positive effect of decreasing IFT was larger in mixed-wet formations than in water-wet formations (Lohne, Purwanto, & Fjelde, 2012).…”

Section: Wettability Effectsmentioning

confidence: 96%

Review of Capillary Number in Chemical Enhanced Oil Recovery

Guo

Ma²,

Wang

et al. 2015

All Days

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After decades of development, great progress has been made in capillary number theory and it has important but often incorrect application in EOR. Investigation into progress on capillary number theory and some misuse of capillary number theory helps to make better use of it. Latest progress concerning with capillary number theory and its application in chemical EOR is reviewed by studying the experiments data and checking its model hypothesis. Classic Capillary Desaturation Curves (CDC) are summarized and new CDC is introduced. Typical classical CDC showed larger capillary number lead to lower residual oil saturation and when capillary number increased to a certain critical value(first critical value), the residual oil saturation could drop to a minimum value even zero. CDC shapes were different in water-wet and oil-wet media. Recovery can be improved by increasing flooding rate, though invalid and impractical, displacement phase viscosity or/and reducing oil/water interfacial tension, which are actually adopted by chemical flooding. Guided by this theory and also first critical capillary number value requirement, it lead to the pursuit of low interfacial tension to largest extent and the requirement of ultra-low interfacial tension (10 -3 mN/m) in surfactant screening. However, experiments data showed that residual oil saturation was not always decreasing as capillary number increased. After capillary number increased to a certain value (second critical value), the residual oil saturation may increase or decrease as capillary number increase. What was more, the final residual oil saturation was quite more than zero and this CDC was regarded as the new CDC. Experiments in heavy oil laboratory tests showed that smaller injection rate lead to higher recovery which seemed contrary to capillary theory.

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Surfactant Flooding in Heterogeneous Formations

Lohne

Fjelde

2012

All Days

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The potential for surfactant flooding of oil fields can be obtained using field-scale surfactant simulation model with capillary number (Nc) dependent relative permeability, k r . Typically, k r (N c ) is solely based on core flood experiments. In this paper, surfactant recovery mechanisms in presence of heterogeneities smaller than the field simulation grid block are investigated. Effects of reducing the interfacial tension, IFT, are investigated in various models by numerical simulation of the displacement process and by steady-state upscaling. It is demonstrated that measured core-scale results should go through appropriate averaging before they are used in a field-scale surfactant model.Macro-scale effects of IFT in presence of small-scale heterogeneities are examined separately. Capillary trapping of oil in heterogeneous formations depends on the geometric distribution of permeability and wettability and on IFT. In general, reduced IFT has little or possibly negative effect on production from water-wet, low-permeability inclusions embedded in a mixed-wet background. Production from mixed-wet, low-permeability inclusions will in general be increased at reduced IFT.The IFT level needed to mobilize capillary trapped oil is proportional to the heterogeneity scale. At normal field flow rates, it was found that oil recovery was sensitive to variation in IFT at scales less than approximately 10 m. IFT reduction down to 1 mN/m was found sufficient for heterogeneities of length scale 10 cm. It is shown that the effect of capillary trapping in heterogeneous formations can be represented as N c -dependent relative permeability function at the larger scale and that the larger-scale functions can be obtained from rate dependent steady-state upscaling. The macro-scale effects described here comes in addition to the measured core-scale effects, and may increase the potential for surfactant flooding. IntroductionMechanisms that might be important in surfactant flooding of an oil field are:1. Micro-scale mechanisms a. Reduced residual oil saturation, S or . b. Altered relative permeability. 2. Macro-scale mechanisms a. Capillary trapping due to the presence of heterogeneities. b. Segregated flow due to gravity. 3. Wettability alteration (affects flow on both scales). This list is not complete, e.g., large scale volumetric sweep efficiency will normally be reduced when the micro-scale mobility is increased by the surfactant. Typically, polymer would be used to reduce the mobility of the surfactant slug, and thus the effect of polymer should also be evaluated before implementation of the method in a field.The micro-scale mechanisms (1) as well as the wettability alteration (3) would be natural targets for experimental investigations. The reduction in S or is known to be a main mechanism in surfactant flooding of water wet formations [1,2] . The potential for surfactant flooding at water-wet conditions is typically represented by a measured capillary desaturation curve (CDC), which is a plot of S or versus the capillary number,...

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Gravity Segregated Flow in Surfactant Flooding

Cited by 3 publications

References 16 publications

Proper Use of Capillary Number in Chemical Flooding

Proper Use of Capillary Number in Chemical Flooding

Review of Capillary Number in Chemical Enhanced Oil Recovery

Surfactant Flooding in Heterogeneous Formations

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