Wettability as Related to Capillary Action in Porous Media

Melrose, J.C.

doi:10.2118/1085-pa

Cited by 137 publications

(68 citation statements)

References 16 publications

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“…(6) erroneously predicts spontaneous water uptake when  < 90, when in fact spontaneous imbibition of liquids in porous media has been shown to require contact angles less than 40 to 50° [51,52]. When describing effects of wettability on capillary pressure of porous media, it is necessary to distinguish between systems of strong (hydrophilic/hydrophobic) and neutral (intermediate) wettability.…”

Section: Assessment Of Gdm Wettabilitymentioning

confidence: 99%

Wettability and capillary behavior of fibrous gas diffusion media for polymer electrolyte membrane fuel cells

Gostick

Ioannidis

Fowler

et al. 2009

Journal of Power Sources

148

162

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The relationship of capillary pressure to liquid saturation for the water-air fluid pair in two different types of gas diffusion media (GDM) used in polymer electrolyte membrane fuel cell (PEMFC) electrodes is elucidated. It is experimentally demonstrated that GDM samples with and without treatment with poly(tetrafluoroethylene) (PTFE) ubiquitously display permanent capillary pressure hysteresis. Water does not imbibe spontaneously into a dry GDM, neither is it ejected spontaneously from a water-saturated GDM.Rather, positive displacement pressure is required to force both water and air into GDMs, whereas the main effect of adding PTFE is to increase the amount of work required for forcing water into the GDM, and to decrease the work required for water removal.Irrespective of PTFE content, the GDM samples tested are generally shown to behave as materials of intermediate (neutral) wettability. The US Bureau of Mines (USBM) wettability index nevertheless shows that water is the preferentially non-wetting phase in PTFE-treated GDMs and the preferentially wetting phase in untreated GDMs. Water-air capillary pressure curves are found to depend on sample thickness, clearly demonstrating that finite-size effects are important. Finally, compression of the GDM is found to increase the capillary pressures for water injection and decrease the capillary pressures required for water withdrawal. These results should aid the design of GDMs with improved water management properties and the modeling of PEMFC electrodes in general.3

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Section: Assessment Of Gdm Wettabilitymentioning

confidence: 99%

Wettability and capillary behavior of fibrous gas diffusion media for polymer electrolyte membrane fuel cells

Gostick

Ioannidis

Fowler

et al. 2009

Journal of Power Sources

148

162

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“…Rao [25] suggests that, in general, calcite becomes more water-wet and quartz more oil-wet as temperature is increased, but the evidence is limited. Some intermediate conditions of temperature have also been examined [17,[26][27][28] with contradictory results so that questions regarding the influence of pressure and especially temperature on wetting properties of crude oils must be regarded as unresolved.…”

Section: Crude Oil Brine and Initially Water-wet Surfacesmentioning

confidence: 99%

“…[26,27] This approach raises the problem of measurement of contact angles in porous media and expression of their likely variability. Aside from this, a broad range of phenomena involving wettability and its effect on capillary action in porous media, such as the effect of convergent/divergent pore throats and initial water saturation [28], have direct impact on imbibition.…”

Section: Wettability and Imbibitionmentioning

confidence: 99%

Wettability and Imbibition: Microscopic Distribution of Wetting and Its Consequences at the Core and Field Scales

Buckley¹,

Morrow²,

Palmer³

et al. 2003

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The main objectives of this project are:(1) to quantify the microscopic distribution of altered wetting that occurs in oil reservoirs as crude oil components adsorb on rock surfaces, and (2) to apply quantitative descriptions of wetting at the microscopic level to interpretation of imbibition in mixed-wet porous media. AbstractThe questions of reservoir wettability have been approached in this project from three directions. First, we have studied the properties of crude oils that contribute to wetting alteration in a reservoir. A database of more than 150 different crude oil samples has been established to facilitate examination of the relationships between crude oil chemical and physical properties and their influence on reservoir wetting. In the course of this work an improved SARA analysis technique was developed and major advances were made in understanding asphaltene stability including development of a thermodynamic Asphaltene Solubility Model (ASM) and empirical methods for predicting the onset of instability. The CO-Wet database is a resource that will be used to guide wettability research in the future.The second approach is to study crude oil/brine/rock interactions on smooth surfaces. Contact angle measurements were made under controlled conditions on mica surfaces that had been exposed to many of the oils in the CO-Wet database. With this wealth of data, statistical tests can now be used to examine the relationships between crude oil properties and the tendencies of those oils to alter wetting. Traditionally, contact angles have been used as the primary wetting assessment tool on smooth surfaces. A new technique has been developed using an atomic forces microscope that adds a new dimension to our ability to characterize oil-treated surfaces.Ultimately we aim to understand wetting in porous media, the focus of the third approach taken in this project. Using oils from the CO-Wet database, experimental advances have been made in scaling the rate of imbibition, a sensitive measure of core wetting. Application of the scaling group to mixed-wet systems has been demonstrated for a range of core conditions. Investigations of imbibition in gas/liquid systems provided the motivation for theoretical advances as well.As a result of this project we have many new tools for studying wetting at microscopic and macroscopic scales and a library of well-characterized fluids for use in studies of crude oil/brine/rock interactions.iv Table of , where v p is precipitant molar volume. Fits to these linear trends are summarized in Table I relationship used is that for A-93+ α-MN (Fig. I-3.5) with a temperature adjustment of -0.0008 RI units/°C. Solution gas is estimated to be xiii composed of methane, ethane, and propane with mole fractions of 0.5, 0.4, and 0. Figure I-3.27. Measured and predicted onset conditions for flocculation from crude oils induced by precipitants from n-pentane to n-pentadecane. Asphaltene molar volume = 2500 ml/mol. Other model parameters are given in Figure II-2.8. Example of the "memo...

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“…However, it has been discovered 19,20,21 that neither phase will spontaneously imbibe nor displace the other at contact angles roughly between 60° to 120°1 2 . Another limitation is the dependence of the value of the limiting contact angle above which spontaneous imbibition will occur on the initial saturation of the core.…”

Section: Amott-harvey Wettability Testmentioning

confidence: 99%

“…However, care must be taken in interpreting the observed optimal recovery at the neutral-wet condition given by the Amott-Harvey index since it has been shown 19,20,21 that this index is relatively insensitive to neutral wettability at contact angles between 60 o and 120 o .…”

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confidence: 99%

Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)

Dandekar¹,

Patil²,

Khataniar³

2008

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Numerous early reports on experimental works relating to the role of wettability in various aspects of oil recovery have been published. Early examples of laboratory waterfloods show oil recovery increasing with increasing water-wetness. This result is consistent with the intuitive notion that strong wetting preference of the rock for water and associated strong capillaryimbibition forces gives the most efficient oil displacement. This report examines the effect of wettability on waterflooding and gasflooding processes respectively. Waterflood oil recoveries were examined for the dual cases of uniform and non-uniform wetting conditions. Based on the results of the literature review on effect of wettability and oil recovery, coreflooding experiments were designed to examine the effect of changing water chemistry (salinity) on residual oil saturation. Numerous corefloods were conducted on reservoir rock material from representative formations on the Alaska North Slope (ANS). The corefloods consisted of injecting water (reservoir water and ultra low-salinity ANS lake water) of different salinities in secondary as well as tertiary mode. Additionally, complete reservoir condition corefloods were also conducted using live oil. In all the tests, wettability indices, residual oil saturation, and oil recovery were measured. All results consistently lead to one conclusion; that is, a decrease in injection water salinity causes a reduction in residual oil saturation and a slight increase in water-wetness, both of which are comparable with literature observations. These observations have an intuitive appeal in that water easily imbibes into the core and displaces oil. Therefore, low-salinity waterfloods have the potential for improved oil recovery in the secondary recovery process, and ultra low-salinity ANS lake water is an attractive source of injection water or a source for diluting the high-salinity reservoir water.As part of the within-scope expansion of this project, cyclic water injection tests using high as well as low salinity were also conducted on several representative ANS core samples. These results indicate that less pore volume of water is required to recover the same amount of oil as compared with continuous water injection. Additionally, in cyclic water injection, oil is produced even during the idle time of water injection. It is understood that the injected brine front spreads/smears through the pores and displaces oil out uniformly rather than viscous fingering.iii The overall benefits of this project include increased oil production from existing Alaskan reservoirs. This conclusion is based on the performed experiments and results obtained on lowsalinity water injection (including ANS lake water), vis-à-vis slightly altering the wetting conditions. Similarly, encouraging cyclic water-injection test results indicate that this method can help achieve residual oil saturation earlier than continuous water injection. If proved in field, this would be of great use, as more oil can be recovered through...

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Wettability as Related to Capillary Action in Porous Media

Cited by 137 publications

References 16 publications

Wettability and capillary behavior of fibrous gas diffusion media for polymer electrolyte membrane fuel cells

Wettability and capillary behavior of fibrous gas diffusion media for polymer electrolyte membrane fuel cells

Wettability and Imbibition: Microscopic Distribution of Wetting and Its Consequences at the Core and Field Scales

Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)

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