Exploration of Architecture and Connectivity of Cleat Arrays in Coals of The Lorraine CBM Play by the Means of X-Ray Computer Tomography

Pryvalov, V.A.; Pironon, Jacques; Izart, Alain; Morlot, Christophe

doi:10.3997/2214-4609.201700758

Cited by 3 publications

(2 citation statements)

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“…This means that interconnected cleat networks in coal can be represented as an assemblage of rescaled self- copies [Jing et al, 2017]. The fragmentation of coals [Pryvalov et al, 2017] into elementary self-similar subordinated blocks is of high importance to serve as the model capable of simulating connectivity in coal samples.…”

Section: Methodology Of Tomography Experiments For Investigating Mult...mentioning

confidence: 99%

Multi-scale structural inheritance of fracture systems pattern in coal-bearing measures of the Lorraine-Saar coal Basin

Pryvalov

Pironon

Donato

et al. 2022

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The Lorraine-Saar Basin (LSB) is one of the major Paleozoic coalfields of Western Europe that has been shapedover two centuries as a heartland of underground coal mining and associated industrial activities in the transborderarea of France and Germany. The Basin still has considerable coal reserves accumulated in numerous laterally continuous coal seams that were affected by processes of thermogenic production of gaseous hydrocarbons during post-Carboniferous burial and related coalification. The LSB stands out by its up to 6 km sedimentary column and its inversion resulting in Paleozoic erosion in the range of 750 m (French part of the Basin) and pre-Mesozoic (Permian) erosion between 1800 and 3000 m (German part of the Basin). Historically, coal production in the Lorraine and the Saar portions of the entire Basin was associated with numerous mining hazards because of the high methane content in coal seams. The LSB has the potential to host an enormous unconventional resource base including coalbed methane (CBM). Coal mines here are no longer operated to produce coal; however, methane generated in deep compartments is venting here via fracture swarms to the Earth’s surface. Cutting natural methane emissions throughout CBM production within coal-bearing terrains is a crucial opportunity for slowing global warming rates. Nearly all CBM plays worldwide are affected in some way by natural multiscale fracture sets ranging from large fault zones to closely spaced joints, micro-shears, or cleat sets in coal seams. The LSB is not excluded indeed from this trend because of the long-term experience of geological exploration during extensive coal mining in the past. Characterization of structural patterns of fracture networks at different scales is a pragmatic process boosting the reliable perception of the performance of coalbed methane gas reservoirs. The focus of this contribution is to get an insight into the style and kinematic description of the multi-scale fault and cleat patterns in the LSB based on results of subsurface and underground geological mapping, and X-ray computer tomography. It will benefit the right mindset to ensure proper technical decisions for efficient exploration and exploitation of CBM reservoirs in the Basin.

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Section: Methodology Of Tomography Experiments For Investigating Mult...mentioning

confidence: 99%

Multi-scale structural inheritance of fracture systems pattern in coal-bearing measures of the Lorraine-Saar coal Basin

Pryvalov

Pironon

Donato

et al. 2022

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“…The X-ray CT is a non-destructive technique used to inspect the internal structure of solid specimen based on recording abnormal attenuations levels of X-rays after passing them through a specimen. The X-ray measurements are dependent on density contrasts within studied specimen (Pryvalov et al, 2017). Two samples (A57331-1 and AM16161) have been chosen for their sufficient density contrasts between skeleton and matrix.…”

Section: Methodsmentioning

confidence: 99%

Lower Jurassic corals from Morocco with skeletal structures convergent with those of Paleozoic rugosan corals

Vasseur

Boivin

Lathuilière

et al. 2019

Palaeontol Electron

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Neorylstonia nom. nov. pseudocolumellata, a replacement name for Mesophyllum pseudocolumellatum Beauvais, 1986, is only known from uppermost Sinemurian to uppermost Pliensbachian (Lower Jurassic) strata of Morocco. This solitary coral species went extinct during the Pliensbachian-Toarcian transition (~183.5 My), which is currently considered to be a second order biodiversity crisis linked to a period of rapid and global paleoenvironmental disturbances. Neorylstonia pseudocolumellata has a distinctive skeletal organization. The axial structure of the corallite, which has no equivalent in Mesozoic taxa, is reminiscent of the skeletal organization of some Paleozoic rugose corals such as Amygdalophyllum Dun and Benson, 1920, or Rylstonia Hudson and Platt, 1927. This similarity is based on the occurrence of a calicular boss also named pseudocolumella. As Rugosa and Scleractinia do not appear closely related, we consider that this feature cannot be due to evolutionary inheritance from a Rugosan ancestor. The morphological aspects of the skeleton have been assessed in order to understand the function and growth of this axial "calicular boss" as well as to more precisely describe the genus and species characters. The organization of the septal apparatus points to a typical Scleractinian pattern, which is also supported by the original aragonitic mineralogy of the skeleton. This implies a convergence phenomenon, leaving open the question of the functional significance of such a calicular organization. We posit that this feature was used for sexual reproduction and so did not always develop in a population.

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Natural Fracture Systems in CBM Reservoirs of the Lorraine–Saar Coal Basin from the Standpoint of X-ray Computer Tomography

et al. 2020

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The Lorraine–Saar Basin is one of the largest geologically and commercially important Paleozoic coal-bearing basins in Western Europe and has considerable coal reserves in numerous coal beds. The basin stands out due to its sedimentary column of up to 6 km and its inversion, resulting in Paleozoic low-amplitude erosion at around 750 m (French part of the basin) and pre-Mesozoic (Permian) erosion between 1800 and 3000 m (the Saar coalfield or German part of the basin). Thermal maturation of organic matter in sedimentary clastic rocks and coal seams has led to the formation of prolific coalbed methane (CBM) plays in many domains throughout the Carboniferous Westphalian and Stephanian sequences. Coal mines here are no longer operated to produce coal; however, methane generated in “dry gas window” compartments at a depth exceeding 3.5 km has escaped here via several major faults and fracture corridors forming “sweet spot” sites. Faults and a dense network of tectonic fractures together with post-mining subsidence effects also increased the permeability of massive coal-bearing and provided pathways for the breathing of environmentally hazardous mine gases. Nearly all CBM plays can be classified as naturally fractured reservoirs. The Lorraine–Saar Basin is not excluded, indeed, because of the experience of geological surveys during extensive coal-mining in the past. The knowledge of geometrical features of fracture patterns is a crucial parameter for determining the absolute permeability of a resource play, its kinematics environment, and further reservoir simulation. The main focus of this contribution is to gain an insight into the style and structural trends of natural cleat patterns in the basin based on the results of X-ray computer tomography (CT) to ensure technical decisions for efficient exploration of CBM reservoirs. To explore the architecture of solid coal samples, we used X-ray CT of a coal specimen collected from Westphalian D coal from exploratory well Tritteling 1. The studied coal specimen and its subvolumes were inspected in three series of experiments. At different levels of CT resolutions, we identified two quasi-orthogonal cleat systems including a smooth-sided face cleat of tensile origin and a curvilinear shearing butt cleat. The inferred cleat patterns possess features of self-similarity and align with directional stresses. Results of the treatment of obtained cleat patterns in terms of their connectivity relationship allowed the presence of interconnected cleat arrays to be distinguished within studied samples, potentially facilitating success in CBM extraction projects.

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Exploration of Architecture and Connectivity of Cleat Arrays in Coals of The Lorraine CBM Play by the Means of X-Ray Computer Tomography

Cited by 3 publications

References 0 publications

Multi-scale structural inheritance of fracture systems pattern in coal-bearing measures of the Lorraine-Saar coal Basin

Multi-scale structural inheritance of fracture systems pattern in coal-bearing measures of the Lorraine-Saar coal Basin

Lower Jurassic corals from Morocco with skeletal structures convergent with those of Paleozoic rugosan corals

Natural Fracture Systems in CBM Reservoirs of the Lorraine–Saar Coal Basin from the Standpoint of X-ray Computer Tomography

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