Thermal Evolutions and Resulting Microstructural Changes in Kerogen-Rich Marcellus Shale

Abstract

Shale rock is a complex geochemical system, which contains inorganic minerals and organic matter (e.g., kerogen), of which the latter possesses porous, high-molecular-weight carbon structures. The pores within organic matter hold the majority of recoverable unconventional oil and natural gas. The organic matter also provides a possible source of hydrocarbon fuel upon pyrolysis. To promote engineering developments in hydrocarbon recovery using heating methods, it is essential to have a fundamental understanding of the nature of the thermal behavior of shale. Consequently, we have investigated the thermal evolution of a shale sample from the Marcellus Formation, Pennsylvania, using a multi-faceted materials science approach, including in situ X-ray diffraction, in situ diffuse reflectance spectroscopy, thermogravimetric analysis coupled with differential scanning calorimetry and mass spectrometry, and transmission electron microscopy. Our aim was to link the naturally heterogeneous and complex chemistry of the shale with its mineralogy and thermal stability up to 900 °C. The thermally induced decomposition of organic and inorganic phases resulted in systematic changes in the shale characteristics. More specifically, kerogen underwent complex decomposition reactions between 200 and 600 °C, depending upon the heating rate and atmosphere (oxidative or inert); pyrite decomposed from 300 to 400 °C; and above 600 °C, inorganic minerals, such as carbonate and clay, broke down. These decompositions created microscopic cracks and left empty pores within the rock. Our results provide insight into the pyrolysis process of shale for hydrocarbon recovery.

Thermodynamic, Thermal, and Structural Stability of Bimetallic MIL-53 (Al1–xCrx)

“…The coordinated BDC linkers of MIL-53 (Al 1– x Cr x ) are decomposed and fully combusted to the final metal oxide products Al 2 O 3 for MIL-53 (Al), Cr 2 O 3 for MIL-53 (Cr), and a Al 2 O 3 /Cr 2 O 3 mixed phase for MIL-53 (Al 0.5 Cr 0.5 ). The additional peaks at above 600 °C for MIL-53 (Al) and 400 °C MIL-53 (Al 0.5 Cr 0.5 ) and MIL-53 (Cr) are from the platinum (Pt) crucible, which hosts the samples during the in situ XRD experiments, as observed in our earlier studies. − , Therefore, according to the in situ XRD results, we conclude that MIL-53 (Al 1– x Cr x ) present pore-filled Pnma structure up to initiation of phase transition estimated at ∼300 to 400 °C (see Figure ) after removal of pore-confined H 2 BDC molecules, followed by relatively stable pore-empty Imma structure up to ∼400 °C for MIL-53 (Cr) to higher than 500 °C for MIL-53 (Al), after which no MIL-53 pattern shows due to decomposition and combustion.…”

“…Specifically, the transition from the Pnma to Imma phase is observed to conclude at ∼400 °C supported by thermal analysis results, which suggest complete combustion of poreconfined H 2 BDC molecules (see Figure 4). Subsequently, at higher temperature, from 500 to 600 °C for MIL-53 (Al [31][32][33][34]54 Therefore, according to the in situ XRD results, we conclude that MIL-53 (Al 1−x Cr x ) present pore-filled Pnma structure up to initiation of phase transition estimated at ∼300 to 400 °C (see Figure 5) after removal of pore-confined H 2 BDC molecules, followed by relatively stable pore-empty Imma structure up to ∼400 °C for MIL-53 (Cr) to higher than 500 °C for MIL-53 (Al), after which no MIL-53 pattern shows due to decomposition and combustion.…”

Reservoir characterization of the shallow to deep Longmaxi formation in the Weiyuan Block, southwestern Sichuan Basin

“…One disadvantage of conducting low-pressure gas adsorption experiments is that they are limited in their ability to provide pore structure information for only small openings (Cockreham et al, 2020; Fu et al, 2022; Wei et al, 2019; Yu et al, 2019; 2022). Although the pore structures can be quantified, they cannot match such microstructural information with organic matter or inorganic mineral carriers.…”

Unveiling the Interfacial and Structural Heterogeneity of Ti3C2Tx MXene Etched with CoF2/HCl by Integrated in Situ Thermal Analysis

“…MS, DTG, and DDSC curves were smoothed in Origin using the Adjacent-Average method with 5 points. This system was also used in our earlier studies on MXenes, shale rocks, zeolites, and layered double hydroxides (LDHs). ,− …”