Discussion of shale rock wettability and the methods to determine it

Sheng, James J.

doi:10.1002/apj.2263

Cited by 25 publications

(13 citation statements)

References 64 publications

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“…According to the published data, the contact angle for shale rock may vary from 11 to 103 • (Sheng, 2018;Siddiqui et al, 2018). For example, Lower Silurian Longmaxi shale samples are characterized by an 11-39 • contact angle (strongly water-wet).…”

Section: Discussionmentioning

confidence: 99%

Wettability of organic-rich source rocks: case study on Bazhenov Formation (Abalak-Bazhenov group)

et al. 2020

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Abstract. In this work, we have investigated the wettability of Bazhenov Formation rock samples using a nuclear magnetic resonance (NMR), the methods of vapor adsorption, and wetting contact angle. We have conducted the petrographic description of rocks using ultra-thin sections and scanning electron microscopy (SEM). In addition, we used data on the organic content (TOC) obtained by the Rock-Eval method and the results of lithological typing on thin sections for detailed analysis of NMR and contact angle methods results. Thus, for target rock, the groups with a similar rock wettability were highlighted by the lithological description of thin sections. The calculation of the wetting angle provided an initial assessment of the surface wettability of the rock and made it possible to establish the relationship between the wetting angle and the TOC, which is relevant for rocks of the Abalak-Bazhenov group. The NMR method described the core plug wettability proved to be less sensitive to the rock lithotype and organic matter (OM) texture in the rock and, therefore, used for the integral characterization of core plugs. Correlations of calculated wetting angle and adsorption wettability index vs. TOC and OM texture illustrated the dependence of rock wettability behavior on both the lithological specifics and the OM properties.

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Section: Discussionmentioning

confidence: 99%

Wettability of organic-rich source rocks: case study on Bazhenov Formation (Abalak-Bazhenov group)

et al. 2020

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“…It was highlighted earlier that previous investigations of shale hydration under confinement were performed under dynamic imbibition conditions where some injection pressure was used to hydrate the core (Sheng & Sheng, ; Zhang & Sheng, , ). However, in this study, to represent truly SI conditions, the core holder cap was left slightly untightened leaving a small space between cap and the sample surface, Figure .…”

Section: Experimental Methodologymentioning

confidence: 99%

“…Siddiqui et al (2018) recently opined in their comprehensive review that CA-based wettability estimated in an oil-water system is consistent rather than in an air-water system. Later, Sheng (2018) concluded that even SI should be performed in an oil-water system. Despite this, the reasons for inconsistency between air-fluid CAs and air-fluid SI have not been identified yet-which will be explored in this study.…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Study on Shale Wettability: Spontaneous Imbibition Versus Contact Angle

Siddiqui

Xiao

Iglauer

et al. 2019

Water Resources Research

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Environmental and technical issues associated with hydraulic fracturing fluid leak-off and its low recovery in clay-rich shale reservoirs has challenged the energy sector. One of the main hypothesized mechanisms for the uptake of fracturing fluid is fluid imbibition due to capillary forces that are a strong function of the rock's wettability. However, shale wettability estimated by contact angle and spontaneous imbibition experiments are highly inconsistent throughout the literature. It is therefore critical to shed light on the possible reasons for such discrepancies and identify the superior technique. In order to characterize the physical processes from microscale to macroscale, the contact angles and spontaneous imbibition characteristics of shale samples were measured using aqueous ionic solutions (NaCl, KCl, CaCl 2 , and MgCl 2 ) at different concentrations (0, 0.1, and 0.5 M) and oil (Soltrol-130). The internal structure of the samples exposed to deionized water was imaged by three-dimensional X-ray micro-computed tomography before and after spontaneous imbibition at both unconfined and confined stress states. Additionally, the structure of all samples exposed to each ionic solution was analyzed via environmental scanning electron microscopy. Experimental observations were further substantiated by combining digital image correlation with Poisson-Boltzmann analysis to assess the hydration-induced strains. It was shown that while spontaneous imbibition is a more realistic measurement for liquids, results obtained under unconfined condition can be highly biased due to additional forces acting (e.g., osmotic or hydration forces) and also potential microstructural alterations. Thus, spontaneous imbibition measured under reservoir stress condition is strongly recommended for shale wettability estimation.

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“…e higher the maturity of organic matter, the stronger the lipophilicity [30]. e simultaneous appearance of inorganic water-wet macropores and organic oil-wet small pores makes shale have double wettability, which is also where the wettability of shale oil reservoirs is different from that of conventional reservoirs [31].…”

Section: Introductionmentioning

confidence: 99%

Study on the Wettability and Spontaneous Imbibition Characteristics of Lacustrine Shale

et al. 2022

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Wettability plays a significant role in the exploration and development of shale oil. The wettability affects the oil enrichment and restricts the selection of fracturing fluids. Shale is composed of complex minerals and organic matter. The pores composed of inorganic minerals have water wettability, while the pores composed of organic matter show the characteristics of oil wetting. The contact angle experiment and the spontaneous imbibition experiment are the most commonly used methods for characterizing wettability. The Qingshankou Formation in the Songliao Basin has thick source rocks, which is a favorable interval for shale oil exploration and development. Strengthening the wettability research in this area is of great significance for the exploration of shale oil. The wettability of different lithofacies shale in the northern Songliao Basin is seldom characterized, and there is a lack of comparative studies on contact angle and imbibition characteristics. In view of this situation, the shale of the Qingshankou Formation in the northern Songliao Basin has been classified. This article used the method of spontaneous imbibition combined with nuclear magnetic resonance to characterize the wettability of shale and analyze the influencing factors of the wettability of different shale lithofacies. Six samples with different lithological characteristics were used for this experiment. The study found that the imbibition results of samples with different lithofacies are different. The imbibition of sandy interlayer is less affected by the direction, while the imbibition of shale is more affected by the direction. The water imbibition volume of the sample is related to the content of clay minerals. The relationship of water imbibition volume in different lithofacies samples is as follows: low organic matter laminated siliceous shale > high organic matter massive clay shale > sandy interlayer > high organic matter laminated siliceous shale > high organic matter massive siliceous shale. Excessive content of clay minerals will cause shale to absorb water and expand and block pores, which is not conducive to further water imbibition by shale. The volume of oil imbibed is related to the organic carbon content. The relationship of oil imbibition volume in different lithofacies samples is as follows: high organic matter massive clay shale > high organic matter laminated siliceous shale > sandy interlayer > low organic matter laminated siliceous shale > high organic matter massive siliceous shale. The higher the total organic carbon content, the more developed the lipophilic pore network, and the more the volume of oil imbibed by the sample.

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Discussion of shale rock wettability and the methods to determine it

Cited by 25 publications

References 64 publications

Wettability of organic-rich source rocks: case study on Bazhenov Formation (Abalak-Bazhenov group)

Wettability of organic-rich source rocks: case study on Bazhenov Formation (Abalak-Bazhenov group)

A Multiscale Study on Shale Wettability: Spontaneous Imbibition Versus Contact Angle

Study on the Wettability and Spontaneous Imbibition Characteristics of Lacustrine Shale

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