Complexities Driving Wettability Evaluation of Shales toward Unconventional Approaches: A Comprehensive Review

Sharifigaliuk, Hamid; Mahmood, Syed Mohammad; Al-Bazzaz, Waleed; Khosravi, Vahid

doi:10.1021/acs.energyfuels.0c03661

Cited by 22 publications

(23 citation statements)

References 102 publications

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“…There was no meaningful relationship between the measured properties of subsurface and outcrop samples. It is worth noting that abundant nanopores are generated in the OMs during thermal maturation of subsurface shale 106 which increases the gas sorption.…”

Section: Comparison Based On Geochemicalmentioning

confidence: 99%

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Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

et al. 2021

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Full coring in shale reservoirs is challenging, time consuming, and risky due to fragility. Therefore, shale outcrop analogs are often used as an alternative to enhance the understanding of corresponding subsurface reservoir formation multifaceted mineralogy and rock characteristics. As consequence, many researchers perform their fundamental experimental studies on the core samples collected from outcrops when the subsurface unconventional shale samples are scarce. An assumption is often made that the rock composition and properties of outcrop and subsurface samples remain the same which raises some serious concerns and demands a thorough review of published research to check the validity of this approach to characterize shale reservoirs. The high degree of lateral and vertical heterogeneity and anisotropy, weathering, contamination, and postdepositional tectonic activities further add to the major challenges. In this literature-based study, the authors revisit the current understanding and challenges of using shale outcrops to complement the available subsurface samples and use them for the preliminary evaluation of underexploration and undeveloped unconventional shale reservoirs. The similarities and discrepancies of mineralogical, petrophysical, geochemical, and geomechanical properties are discussed. Finally, some concluding remarks and recommendations are presented.

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Section: Comparison Based On Geochemicalmentioning

confidence: 99%

“…108 Wettability is not solely dependent on the TOC content of the rock. 106 In a study, Hu 109 constructed kerogen with varying degrees of maturity and compared it with a molecular dynamics approach. He observed a close relationship between water contact angle and kerogen maturity.…”

Section: Comparison Based On Geochemicalmentioning

confidence: 99%

Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

et al. 2021

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“…e pore composition and connectivity of shale are complex [25][26][27][28]. Generally speaking, pores composed of inorganic minerals are hydrophilic, and pores distributed in organic matter are lipophilic [29]. e higher the maturity of organic matter, the stronger the lipophilicity [30].…”

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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“…Although numerous researches have been done on the pore structure, interphase interaction, and flow mechanisms in macroscale [22][23][24][25][26], mathematical models capable of accurately characterizing the pore deformation, dynamic capillary force phenomenon, and oil-water two-phase transport at the nanopore scale for shale oil are still missing [27][28][29][30][31]. To solve this problem, Gassmann's method is modified to describe the change of pore radius and roughness in the dynamic pressure field for elastic deformation.…”

Section: Introductionmentioning

confidence: 99%

Study on Two-phase Flow Mechanisms in Nanopore Considering Microcosmic Deformation and Dynamic Capillary Force

et al. 2022

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Coring experiments show that nanopores are extensively distributed in shale oil reservoirs and tend to be deformed when a significant pressure variation exists, and thus the dynamic capillary force phenomenon and flow mechanisms in nanopores can be significantly changed. To characterize the two-phase flow mechanisms in nanopores influenced by the synergistic effect of microcosmic pore deformation and dynamic capillary force, models based on Gassmann’s theory are established to describe the variations of pore radius and roughness in a dynamic pressure field. And then, innovative methods to quantify the dynamic capillary force phenomenon under comprehensive influence of pore size, roughness, and pressure are developed. Meanwhile, mathematical models, considering the effect of the pore deformation and dynamic capillary force, are furtherly derived to characterize the water-oil two-phase flow behavior for relatively large nanopores in shale oil reservoir, which can be used to investigate the influence of the vital parameters. The results indicate that the dynamic capillary force phenomenon turns out to be more significant when variations of pore structure and pressure are considered simultaneously. Moreover, the pore deformation and dynamic capillary force caused by pressure change can exert remarkable synergistic influence on the transport capacity for typical flow modes. Bulk modulus is one of the key factors to determine the degree of influence. An optimal pressure can be obtained to coordinate the competitive effect of seepage channel and capillary force for water-drive-oil mode with limited driving force. Based on that, emphasis should be placed on pressure control during the shale oil development process. This work theoretically underpins the quantitative characterization and the analysis of two-phase flow in shale reservoirs at the nanopore scale.

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Complexities Driving Wettability Evaluation of Shales toward Unconventional Approaches: A Comprehensive Review

Cited by 22 publications

References 102 publications

Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

Study on the Wettability and Spontaneous Imbibition Characteristics of Lacustrine Shale

Study on Two-phase Flow Mechanisms in Nanopore Considering Microcosmic Deformation and Dynamic Capillary Force

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