Porosity evolution of two Upper Carboniferous tight-gas-fluvial sandstone reservoirs: Impact of fractures and total cement volumes on reservoir quality

Busch, Benjamin; Becker, Ivy; Koehrer, Bastian; Adelmann, Dirk; Hilgers, Christoph

doi:10.1016/j.marpetgeo.2018.10.051

Cited by 41 publications

(18 citation statements)

References 50 publications

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“…Detailed petrographic analyses can be found in the previous studies by Becker et al (2017), Wüstefeld et al (2017a and Busch et al (2019). Their results indicate a subordinate control on reservoir quality by differences in the detrital composition.…”

Section: Petrographymentioning

confidence: 74%

“…4; see data table in online archive). All the sandstones show wide ranges of grain sizes: fi ne-to coarse-grained at Piesberg (Wüstefeld et al, 2017a), medium-to coarse-grained at Woitzel, fi ne-to coarse-grained at Hüggel (Becker et al, 2017), fi ne-to medium-grained at Well A, and very fi ne-to coarse-grained at Well B (Busch et al, 2019). Average grain sizes were 0.4 mm in the outcrop sandstones and 0.3 mm in the subsurface sandstones.…”

Section: Petrographymentioning

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: Petrographymentioning

confidence: 74%

Section: Petrographymentioning

confidence: 99%

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 study comprises of fluvio-eolian sandstones only, consequently a population bias against a strong control depositional control due to the lack of depositional system variety is introduced into the data set. As opposed to Heidsiek et al (2020) a facies dependent reservoir control on plug-scale reservoir quality analyses cannot be delineated in Flechtingen Sandstones, as is also supported by previous studies in similar arid or semi-arid fluvio-eolian deposits (Busch et al 2019(Busch et al , 2020Kunkel et al 2018;Monsees et al 2020a). The effect of grain size on permeability is also interpreted to be partly caused by a population bias, which is also discussed by Wadsworth et al (2016).…”

Section: Depositional Parametersmentioning

confidence: 63%

Compaction control on diagenesis and reservoir quality development in red bed sandstones: a case study of Permian Rotliegend sandstones

Monsees

Busch

Hilgers

2021

Int J Earth Sci (Geol Rundsch)

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Authigenic minerals formed during diagenesis in conjunction with compaction by burial have long been known to lead to porosity-loss of sandstones, and a subsequent deterioration in reservoir quality. The diagenetic impact on reservoir quality and permeability heterogeneity measured horizontal and vertical to bedding was characterized in three fluvio-eolian Lower Permian Rotliegend outcrops from the Flechtingen High, the northern Hesse Basin (both Germany) and the Vale of Eden (UK) using point-counting, polarized light-microscopy, helium pycnometry and permeability measurements. Results show significant porosity (10 to 35%) and permeability (0.01 to 10,000 mD) ranges largely independent of depositional environment. The major control on reservoir quality in Cornberg Sandstones are dolomite and siderite cementation in conjunction with illitization and illite and kaolinite cementation, leading together with quartz cementation to a mostly cemented IGV and poorest reservoir quality (avg. horizontal permeability: 0.96 mD). Flechtingen Sandstones are most intensely compacted due to the lack of significant early diagenetic cement phases and continuous illitic grain-to-grain coatings, which inhibited intense quartz cementation but enhanced chemical compaction at quartz grain contacts, resulting in intermediate reservoir quality (avg. horizontal permeability: 34.9 mD). Penrith Sandstones lack significant authigenic phases besides quartz due to carbonate dissolution during uplift. They show the least amount of detrital feldspars and clay minerals, leading to no major reservoir quality reduction by burial diagenetic clay mineral alterations, resulting in the highest reservoir quality (avg. horizontal permeability: 5900 mD). Additional results highlight higher horizontal to vertical permeability ratios kh/kv in less homogeneous sandstones of < 10 mD of 10, and in more homogenous, higher permeable sandstones > 1000 mD of 1. Although detrital and authigenic sample compositions vary throughout the studied areas, the general effect of grain coatings coverages on syntaxial cement inhibition and chemical compaction can be delineated. This study increases the understanding of porosity reduction in sandstones, as it confirms the necessity to differentiate between the illitic grain-to-grain coatings and illitic grain-to-IGV coatings. As a result, the enhancing effect of illite on chemical compaction on quartz grain-grain boundaries can be better constrained, as well as the effect of grain coatings on quartz cementation. This is relevant for reservoir quality and risk assessment in hydrocarbon and geothermal plays as well as in storage.

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“…To characterize a reservoir, the knowledge of its rock properties (e.g., lithology, porosity and permeability), diagenetic alterations controlling not only porosity and permeability but also affecting mechanical properties, structural inventory as the fracture network, the heat transfer, and all resulting interactions are crucial (Becker et al, Published by Copernicus Publications on behalf of the European Geosciences Union. Busch et al, 2019Busch et al, , 2020. In recent years, outcrop analog studies aiming at providing high-resolution data for a subsurface reservoir model have been increasingly supported by the use of digital techniques as UAS and terrestrial laser scanning to complement traditional fieldwork data (e.g., Becker et al, 2018;Cawood et al, 2017;Hodgetts, 2013;Walter et al, 2020;Wüstefeld et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Thermal UAS survey of reactivated hot spring activity in Waiwera, New Zealand

et al. 2020

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Abstract. The utilization of geothermal reservoirs as alternative energy source is becoming increasingly important worldwide. Through close-range aerial photogrammetry realized by unmanned aircraft systems (UAS), this study investigates the surface expression of a leaking warm water reservoir in Waiwera, New Zealand, that has been known for many centuries but remained little explored. Due to overproduction during the 1960s and 1970s the reservoir has suffered significant pressure reduction, which resulted in the loss of artesian conditions and led to the desiccation of the hot springs in close succession. However, shortly after the recent shutdown of the primary user (Waiwera Thermal Resort & Spa) renewed artesian activity was reported by locals but no hot spring activity has been observed so far. Therefore, this study was carried out in October 2019 to assess the actual conditions of thermal activity in the area of the former hot springs. UAS with coupled thermal infrared cameras were used for thermal mapping and the obtained data show renewed activity of the hot springs on the beachfront of Waiwera. Faults and fractures were identified as important fluid pathways, as well as individual fluid conducting lithologies.

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Porosity evolution of two Upper Carboniferous tight-gas-fluvial sandstone reservoirs: Impact of fractures and total cement volumes on reservoir quality

Cited by 41 publications

References 50 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

Compaction control on diagenesis and reservoir quality development in red bed sandstones: a case study of Permian Rotliegend sandstones

Thermal UAS survey of reactivated hot spring activity in Waiwera, New Zealand

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