Effect of total organic carbon (TOC) content on shale wettability at high pressure and high temperature conditions

Pan, Bin; Li, Yajun; Zhang, Mingshan; Wang, Xiaopu; Iglauer, Stefan

doi:10.1016/j.petrol.2020.107374

Cited by 67 publications

(36 citation statements)

References 85 publications

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“… 27 However, the effect of the content of total organic matter (TOC) on the water contact angles is more complicated. 28 In the air/brine/shale system, the contact angles were found to decrease first (TOC<1.5%) and then increase (TOC>1.5%) with the increase of the content of TOC. 21 The tendency to decrease first and then increase was mainly controlled by the development and distribution of migratory organic matter and the illite/smectite mixed layer.…”

Section: Introductionmentioning

confidence: 92%

Experimental Study of the Wettability Characteristic of Thermally Treated Shale

Yang

Gu²,

Chen

et al. 2020

ACS Omega

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Extraction of shale gas from shale reservoirs is significantly affected by shale wettability. Recently, thermal recovery technologies (e.g., combustion) have been tested for shale gas recovery. This requires an understanding of the wettability change mechanism for thermally treated shale samples. In this study, the effect of combustion on shale wettability was investigated. Shale samples were first processed to obtain smooth surfaces and then combusted at temperatures of 200, 400, and 800 °C. The initial contact angles and dynamic behavior of water droplets on shale surfaces were recorded using the sessile drop method. It was found that pores and fractures were generated on the shale surfaces following high-temperature combustion. The pore volume and diameter increased with increasing combustion temperature, which improved the connectivity of hydrophilic pore networks. Compared to a raw shale sample, the shale sample combusted at 400 °C showed a smaller initial water contact angle and a more rapid decrease in the contact angle because of the oxidation of organic matter and generation of pore structures. Water droplets were found to completely spread over the surface of the shale sample combusted at 800 °C because of the generation of fractures. Moreover, the van der Waals potential between water droplets and combusted shale samples was determined to be stronger. However, the initial contact angle and dynamic behavior of water droplets did not show a significant change for the shale sample combusted at 200 °C. As a result, high-temperature combustion (≥400 °C) can be used to significantly improve the hydrophilicity of shale.

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Section: Introductionmentioning

confidence: 92%

Experimental Study of the Wettability Characteristic of Thermally Treated Shale

Yang

Gu²,

Chen

et al. 2020

ACS Omega

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“…Mokhtari et al found a positive correlation between the air/water contact angle and TOC in samples from some well-known oil and gas shale reservoirs. Samples with a lower clay content, higher TOC content, and higher quartz content have more significant water-repellant properties. , Furthermore, gas shale wettability shifted from water-wet to methane-wet with the TOC content increase . Hence, in gas shales, as the TOC content is increased, water-wetting affinity is decreased.…”

Section: Effect Of the Organic Matter Content On Shale Wettabilitymentioning

confidence: 99%

“…Some researchers found that the water contact angle increases in shales at higher temperatures, , while others decrease. , In a recent study, Pan et al showed that the quartz mineral, as one of the major minerals in gas shales, becomes more water-wet at a high temperature when coated by clays, while it became more methane-wet at low temperatures. Kaolinite had a more substantial influence on quartz wettability than montmorillonite regarding temperature variations.…”

Section: Effect Of Reservoir Conditions On Shale Wettabilitymentioning

confidence: 99%

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

et al. 2021

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Wettability is a challenging property of oil and gas shale reservoirs, which are geologically and geochemically intricate formations. Furthermore, the mineral composition, organic matter content, generated pore types, pressure, temperature, and saturation conditions significantly affect the observed wetting affinity. Hence, a deep understanding of the complexities facing the researchers is needed. This review analyzes the most relevant published research on the wettability evaluation of shales for a better understanding and delineation. Here, the effects of shale composition, organic matter content, maturity, pore types, and reservoir conditions are addressed. It also focuses on the unconventional and emerging approaches to the wettability evaluation of shales. At last, future perspectives, concluding remarks, and recommendations are presented.

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“…Furthermore, Ma et al, Ji et al, and Tohidi et al reported that hydrate is formed in the center of both large and small pores, leaving a liquid film coating the water-wet surface, implying non-hydrate wettability. Pan et al − discussed CO 2 and CH 4 wettabilities of organic-rich shale and quartz. They reported wettability shift from hydrophilic to hydrophobic; however, their study did not measure the effect of wettability on hydrate formation and dissociation.…”

Section: Introductionmentioning

confidence: 99%

Influence of Rock Wettability on THF Hydrate Saturation and Distribution in Sandstones

et al. 2021

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Natural gas trapped in hydrate deposits is a potentially enormous source of energy which can in principle be extracted from the underground reservoir structures. These reserves can potentially also catastrophically release very large quantities of greenhouse gases to the atmosphere. One key parameter which is well known to strongly influence fluid distribution, saturation, and production is rock wettability. However, the effect of wettability on gas hydrate in sediments has not been investigated yet. We thus used nuclear magnetic resonance (NMR) spectrometry to measure relaxation times (T 2 and T 1 ) and the corresponding surface relaxivity of tetrahydrofuran hydrate during the formation and dissociation in water-and oil-wet Bentheimer sandstones. We also measured the NMR porosities and hydrate saturations at different temperatures during hydrate formation/dissociation for both water-wet and oil-wet sandstones. Significantly higher hydrate saturation was observed in the water-wet sandstone (when compared to the oil-wet sandstone) at all stages of hydrate formation and dissociation. Furthermore, the T 2 spectra moved from the lower relaxation domain (before hydrate formation) to the fast relaxation domain (after hydrate formation) in both water-wet and oil-wet sandstones. However, the water-wet sandstone generally had a T 2 relaxation range due to the higher water affinity to the water-wet rock and the associated faster demagnetization of the water molecules. These results demonstrate that low-field NMR can be used to quantify the rock wettability and observe hydrate behavior in geologic sediments. This fundamental information thus aids in the development of gas extraction from hydrate reservoirs and the assessment of potential greenhouse gas emissions from such reservoirs into the atmosphere.

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Effect of total organic carbon (TOC) content on shale wettability at high pressure and high temperature conditions

Cited by 67 publications

References 85 publications

Experimental Study of the Wettability Characteristic of Thermally Treated Shale

Experimental Study of the Wettability Characteristic of Thermally Treated Shale

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

Influence of Rock Wettability on THF Hydrate Saturation and Distribution in Sandstones

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