Critical evaluation of an Upper Carboniferous tight gas sandstone reservoir analog: Diagenesis and petrophysical aspects

Wüstefeld, Patrick; Hilse, Ulrike; Koehrer, Bastian; Adelmann, Dirk; Hilgers, Christoph

doi:10.1016/j.marpetgeo.2017.05.034

Cited by 30 publications

(36 citation statements)

References 39 publications

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“…Outcrop sampling included both vertical and horizontal profiles (Becker et al, 2017;Wüstefeld et al, 2017a). Upper Carboniferous sandstone samples were drilled horizontally in the quarries using a watercooled core drill.…”

Section: Methodsmentioning

confidence: 99%

“…The permeability of outcrop plug samples was measured using single-phase gas flow in an isostatic flow cell (cf. Becker et al, 2017;Wüstefeld et al, 2017a). Helium (η = 1.98*10 -5 Pa*s at 20°C) was used as a permeant with pressures in the range of 1.5 to 9 MPa according to sample properties.…”

Section: Methodsmentioning

confidence: 99%

“…In the Piesberg quarry, a 135 m thick upper Westphalian C to Westphalian D succession (Wüstefeld et al, 2017a) consists of fining-upwards cycles ranging from conglomerates to sandstones and siltstones and coal seams. Sandstone units are up to 40 m thick and are composed of compound channel deposits which extend laterally for up to tens of kilometres (Jones and Glover, 2005;Wüstefeld et al, 2017a).…”

Section: Lithologymentioning

confidence: 99%

“…A number of studies of Upper Carboniferous sandstones in outcrops in NW Germany have been published focussing on the sedimentology and mineralogy of the deposits, on depositional geometries, and on sequence cyclicity (David, 1990;Sedat et al, 1992;Jones and Glover, 2005). Petrophysical data have been linked to structural and diagenetic characteristics to explain lateral and vertical variations in porosity and permeability (Becker et al, 2017;Wüstefeld et al, 2017a;Wüstefeld et al, 2017b).…”

Section: Introductionmentioning

confidence: 99%

“…In the context of these studies, the present paper aims to link data obtained from three outcrops of Upper Carboniferous fluvial sandstones (at Piesberg, Woitzel and Hüggel) to subsurface data from wells at two gas fields (Fields A and B, drilled by Wells A and B) located approximately 50 km away (Figs 1b and c). Previous studies have investigated reservoir heterogeneities within a particular study area (Becker et al, 2017;Wüstefeld et al, 2017a;Wüstefeld et al, 2017b) and compared them with those at nearby locations (Woitzel and Hüggel outcrops, see Becker et al, 2017;Well A and B, see Busch et al, 2019). The present study integrates different data sets over larger distances with a focus on matrix porosity and permeability variations.…”

Section: Introductionmentioning

confidence: 99%

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Reservoir Quality Evolution of Upper Carboniferous (Westphalian) Tight Gas Sandstones, Lower Saxony Basin, Nw Germany

Becker

Busch

Koehrer³

et al. 2019

Journal of Petroleum Geology

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This paper investigates reservoir quality development in tight Upper Carboniferous fluvial sandstones (Westphalian C/D) in the Lower Saxony Basin, NW Germany. The study integrates data from three outcrops (Piesberg, Woitzel and Hüggel) in the south of the basin with that from two wells (Wells A and B) located at gas fields approximately 50 km to the north. Petrographic and petrophysical data are related to the diagenetic evolution of the sandstones and the burial and structural history of the Lower Saxony Basin. The outcrop and subsurface data sets are compared in order to investigate the factors controlling reservoir quality evolution. Upper Carboniferous fluvial sandstones from the Woitzel and Hüggel outcrops and from Wells A and B have similar matrix permeabilities (0.01 to 10 mD), but matrix porosities vary between Well A (average 6%), Well B (average 10%), Woitzel (average 15%), and Hüggel (average 19%). Permeability reduction during burial is related to the formation of clay mineral cement, which was mainly controlled by variations in both the palaeo‐climate and in the sandstones’ depositional composition. Matrix porosity was controlled by local differences in burial history related to basin inversion tectonics. The greater amount of inversion‐related uplift at Well B (about 2.8 km) resulted in lower thermal exposure of the Westphalian sandstones at this location, which thus show higher matrix porosities than the sandstones at Well A which were uplifted by only about 1.2 km. Further increases in porosity in the outcrop sandstones may be related to the dissolution of carbonate cement during late‐stage uplift in near‐surface conditions. Upper Carboniferous fluvial sandstones from the Piesberg quarry show the poorest reservoir characteristics compared to the samples from the subsurface and the other outcrops, with matrix porosities averaging 6% and permeabilities <0.01 mD. Reservoir quality reduction was controlled by thermal anomalies associated with a large fault at the Piesberg quarry. By contrast, a few outliers in the sample data sets from Well B and the Piesberg quarry, which have permeabilities of more than 100 mD, show that faulting or natural fracturing may enhance reservoir quality within a particular area. Faults/fractures may act as potential migration pathways for leaching fluids, or may provide fracture‐permeability systems with production potential. Depositional setting, burial‐related diagenetic processes and structural characteristics in the Lower Saxony Basin need to be carefully evaluated in order to provide an improved understanding of the reservoir quality of the Upper Carboniferous sandstones.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Lithologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reservoir Quality Evolution of Upper Carboniferous (Westphalian) Tight Gas Sandstones, Lower Saxony Basin, Nw Germany

Becker

Busch

Koehrer³

et al. 2019

Journal of Petroleum Geology

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Tight oil sandstones in Upper Triassic Yanchang Formation, Ordos Basin, N. China: Reservoir quality destruction in a closed diagenetic system

et al. 2018

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An investigation of the Triassic Yanchang Formation, Ordos Basin, N. China, revealed that the diagenesis and quality of tight oil sandstone reservoirs (with an average porosity of 9.83% and an average permeability of 0.96 mD) were controlled by a closed diagenetic system. The carbonate cements observed in the sandstone were derived from decarboxylation of organic matter that occurred in the adjacent mudstones. These reactions supplied CO32−, which reacted with cations derived from grain dissolution in the sandstones. The average size of the diagenetic geochemical system with respect to carbonate cements was small (<6 × 10−2 m3), comprising sandstone and its adjacent mudstone(s). The carbonate cements tend to concentrate in the marginal sandstone, which is taken to indicate that the flux of CO32− into the sandstones limited the quantity of carbonate precipitated. In addition, the mass is near balance between the amount of feldspar dissolution and its by‐products in the central sandstone (distance to the sandstone/mudstone interface is mainly more than 1 m), where the permeability of sandstone will present a decreasing trend with the increase of feldspar dissolution pores. The pore space of central sandstone will be just redistributed, with primary intergranular pores converting to feldspar dissolution pores and clay mineral micropores. Thus, the best part of the sandstone reservoirs tends to be the central part of sandstone. In particular, sandstones that are more than 2 m thick could be the potential hydrocarbon reservoirs because they retain the best porosity (average of 13.6%) and permeability (average of 1.8 mD). The results of our study provide an important guide for the exploration of tight oil sandstones in other petroliferous basins over the world.

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Rock characteristics and reservoir properties of Upper Carboniferous (Stephanian A–B) tight siliciclastic rocks from the Saar–Nahe basin (SW Germany)

Quandt,

Busch,

Greve

et al. 2024

Int J Earth Sci (Geol Rundsch)

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The environmental consequences of mine flooding in the Saar hard coal district, post-mining re-use concepts in the course of the energy transition, and the potential of coalbed methane production require an understanding of subsurface rock properties on the microscale. In this study, mineralogy, microtexture, microstructure, porosity, permeability, and geochemistry of an Upper Carboniferous (Stephanian A–B) drill core recovered in the Saar–Nahe basin are quantified. Based on these data, the diagenetic history and reservoir quality are analyzed regarding mine flooding and coalbed methane potential. The feldspar-poor and igneous rock fragment-free siliciclastic rock succession shows multiple fining upward sequences deposited in a fluvial environment during the pre-volcanic syn-rift phase of the Variscan intramontane Saar–Nahe basin. Intercalated small-scale coarsening upward sequences are related to the floodplain where near-surface soft-sediment deformation and paleosol formation took place. Porosity (< 7%) of the tight siliciclastic rocks is mainly controlled by an interplay of authigenic microporous kaolinite, dissolution porosity, and quartz cement, whereas permeability (< 0.05 mD) shows no systematic variation with petrography. During burial, quartz cements preserved porosity by stabilizing the granular framework against mechanical compaction, while phyllosilicates were ductilely deformed reducing reservoir quality. Relative phyllosilicates and quartz contents and mean grain size are reliably inferred from SiO2/Al2O3 ratios (1.8–28.8), Ba (0.0108–0.0653 wt%), Rb (0.0024–0.0181 wt%), and Sr (0.0013–0.0086 wt%) concentrations measured with a portable x-ray fluorescence analyzer. Regarding coalbed methane production and mine flooding, sealing of cleats and heterogeneous subsurface rock properties due to dynamically changing depositional settings during the Late Carboniferous need to be considered. Graphical abstract

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Critical evaluation of an Upper Carboniferous tight gas sandstone reservoir analog: Diagenesis and petrophysical aspects

Cited by 30 publications

References 39 publications

Reservoir Quality Evolution of Upper Carboniferous (Westphalian) Tight Gas Sandstones, Lower Saxony Basin, Nw Germany

Reservoir Quality Evolution of Upper Carboniferous (Westphalian) Tight Gas Sandstones, Lower Saxony Basin, Nw Germany

Tight oil sandstones in Upper Triassic Yanchang Formation, Ordos Basin, N. China: Reservoir quality destruction in a closed diagenetic system

Rock characteristics and reservoir properties of Upper Carboniferous (Stephanian A–B) tight siliciclastic rocks from the Saar–Nahe basin (SW Germany)

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