Organic Matter Pore Characterization of the Wufeng-Longmaxi Shales from the Fuling Gas Field, Sichuan Basin: Evidence from Organic Matter Isolation and Low-Pressure CO2 and N2 Adsorption

Li, Zhuo; Jiang, Zhenxue; Yu, Hailong; Liang, Zhikai

doi:10.3390/en12071207

Cited by 13 publications

(6 citation statements)

References 64 publications

(189 reference statements)

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“…Although shale oil reservoirs have small natural fractures, they are characterized in the order of the nanodarcy formations. The International Union of Pure and Applied Chemistry (IUPAC) classifies pores on a nanometric scale as macropores (>50 nm), mesopores (2–50 nm), and micropores (2 nm) …”

Section: Background Of the Shale/tight Oil Reservoirmentioning

confidence: 99%

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

et al. 2021

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In recent times, particularly in the 21st century, there has been an alarming increase in the demand for global energy, along with continuous depletion in conventional oil reservoirs. This necessity has incentivized interested scholars and operators worldwide to seek alternative oil resources. To secure such accelerating energy demand, considerable effort has been directed toward the development of previously unconventional oil formations that, in past decades, had remained sidelined. Although shale oil reservoirs have seen tremendous success over the past decade, the continued challenges of rapidly declining oil flow rates and oil retention in the pores continuously persist. Substantial attempts have been made to improve shale-bypassed oil recovery; however, there is little data about the accessibility on recovery mechanisms, especially in the oil field. Furthermore, approachesparticularly, Huff-n-Puff (H-n-P) experiments using conventional proceduresfail to properly represent field conditions and they generate deceptive findings, because the utilized cores are not simulated under realistic reservoir conditions, leaving the significance of critical factors unclear. Therefore, this review study comprehensively and specifically discusses the feasibility of enhanced oil recovery (EOR) methods in unconventional oil reservoirs. Beside addressing the validity of the currently applied H-n-P technology in shale/tight oil reservoirs and underlining some critical gaps regarding laboratory results, modified technology is proposed in this paper for a better field future performance. The study is divided into sections, and each section analyzes the role of one specific H-n-P portion in detail, such as preferable injected solvents, their mechanisms, and critical factors affecting H-n-P recovery. The exceptions to this are the first and second sections, which provide a brief introduction about shale and tight oil reservoirs, a history of applied technology, and the method’s current problem statement. In the Introduction section, the authors will justify why this Review fills a critical gap in the field. Within the assessment study, great focus is given to the H-n-P technique, its parameters, and effective processes. In the final sections, carefully chosen experimental results and tools are reviewed to highlight the controversy and state “the gap”.

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Section: Background Of the Shale/tight Oil Reservoirmentioning

confidence: 99%

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

et al. 2021

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“…The multipoint BET surface area showed a positive trend with average pore size and a strong positive relationship with total pore volume R 2 = 0.83, Fig. 13d), indicating that the shale beds with smaller average pore size have more abundant macropores and mesopores (Chen et al, 2016;Li et al, 2019). The scatter plot between multipoint BET surface area and fixed carbon content shows an average negative correlation (R 2 = 0.55, Fig 13e), signifying that the organic matter does not support gas storage (Hazra et al, 2018b), whereas the BET plot shows a weak positive trend with the ash content that comparatively favors adsorption of gas (Fig.…”

Section: Discussionmentioning

confidence: 94%

Pore structures and fractal dimensions in Early Permian Barakar shales of Rajmahal Basin, Jharkhand, India

et al. 2021

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The proximate, low-pressure N 2 sorption, X-ray diffraction, and organic petrography parameters have been used to delineate the pore structures and fractal dimensions in the Barakar shales of Rajmahal Basin, India. The information has been utilized for the assessment of shale gas reservoir and to know about the mode of occurrence and storage capacity of shales for the entrapment of methane (CH 4 ). The studied shales are characterized by high fixed carbon contents (10.14-46.09 wt.%) and contain significant abundance of brittle minerals, like quartz (6.0-51.6%) and mica (1.0-41.2%). The petrographic observations show that the studied samples comprise of numerous laths of vitrinite (collotelinite and vitrodetrinite) and semifusinite macerals and quartz grains. The data of low-pressure N 2 sorption analysis indicates the shales encompass mainly meso-to macropores and microfractures. The total pore volume, average pore size, and multipoint BET surface area of the studied shales vary from 0.012 to 0.023 cc/g, 8.295 to 10.840 nm, and 5.752 to 10.390 m 2 /g respectively. Two types of fractal dimensions (D 1 and D 2 ) have been calculated by using FHH (Frankel-Halsey-Hill) method from the N 2 adsorption isotherm. The high values of fractal dimensions (2.1949 < D 1 < 2.4837 and 2.6668 < D 2 < 2.7247) are indicating the highly rugged pore surface or complexity in the pore structures.

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“…In particular, some of the clay minerals with mixed OM pores exhibited long strip shapes (Figure d). The interP pores in the shale samples were mainly distributed between the quartzes, feldspars, clay minerals, or calcites (Figure e–g); were triangular and polygonal in shape; and were in contact with each other, forming an effective pore network . The sizes of the interP pores were relatively large, ranging from the nanoscale to microscale.…”

Section: Resultsmentioning

confidence: 99%

“…The interP pores in the shale samples were mainly distributed between the quartzes, feldspars, clay minerals, or calcites (Figure 5e−g); were triangular and polygonal in shape; and were in contact with each other, forming an effective pore network. 32 The sizes of the interP pores were relatively large, ranging from the nanoscale to microscale. The intraP pores were mainly developed within quartzes (Figure 5h) and calcites (Figure 5i), which were relevant to the dissolution in the shales.…”

Section: Mineral Compositions and Organicmentioning

confidence: 99%

Assessment of the Multiphase Mechanical Properties of the Longmaxi Formation Shale Using Nanoindentation Tests

et al. 2021

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Mechanical properties are some of the most important parameters for understanding well drilling and hydraulic fracturing designs in unconventional reservoir development. As an effective tool, nanoindentation has been used to determine the mechanical properties of rocks at the nanoscale. In this study, the Longmaxi Formation shale samples from the Yibin area of China were collected and analyzed to obtain the multiphase mechanical properties. The mineral compositions and organic geochemistry of the shale samples were studied using X-ray diffraction, energy-dispersive X-ray spectrometry, and a carbon/sulfur analyzer. The pore structures of the shale samples at the micro- and nanoscales were characterized by field-emission scanning electron microscopy. The mechanical parameters of the shale samples, such as the hardness and elastic modulus, were investigated using the nanoindentation method to identify three mineral phases: brittle minerals, soft matters, and complex minerals at the interfaces between brittle minerals and soft matters. The uncertainty characteristics of the mechanical parameters of the three mineral phases were evaluated using the Weibull model, and the factors interfering with the mechanical parameters were analyzed for the different shale samples. The results showed that the brittle minerals had the largest recovered elastic deformations and the smallest residual deformations, while the soft matters had the largest residual deformations and the smallest recovered elastic deformations. The analysis results of the coefficients of variation and the Weibull modulus both confirmed that the scatter of the hardness was higher than that of the elastic modulus because of the uncertain contact area, and the hardness and elastic modulus of the soft matters had the highest uncertainty among the three mineral phases. The elastic modulus increased nonlinearly with increasing hardness according to a power function for the whole shale sample. The elastic modulus and hardness both had a favorable linear relationship with the total organic carbon (TOC) content, illustrating that the TOC content was one of the significant factors that affected the mechanical parameters of the shale samples.

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Organic Matter Pore Characterization of the Wufeng-Longmaxi Shales from the Fuling Gas Field, Sichuan Basin: Evidence from Organic Matter Isolation and Low-Pressure CO2 and N2 Adsorption

Cited by 13 publications

References 64 publications

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

Huff-n-Puff Technology for Enhanced Oil Recovery in Shale/Tight Oil Reservoirs: Progress, Gaps, and Perspectives

Pore structures and fractal dimensions in Early Permian Barakar shales of Rajmahal Basin, Jharkhand, India

Assessment of the Multiphase Mechanical Properties of the Longmaxi Formation Shale Using Nanoindentation Tests

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