Fracturing of doleritic intrusions and associated contact zones: Implications for fluid flow in volcanic basins

Senger, Kim; Buckley, Simon J.; Chevallier, L.; Fagereng, Åke; Galland, Olivier; Kurz, Tobias H.; Ogata, Kei; Planke, Sverre; Tveranger, Jan

doi:10.1016/j.jafrearsci.2014.10.019

Cited by 68 publications

(47 citation statements)

References 35 publications

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“…The sandstone succession is highly fractured and intersected by numerous dolerite sills reaching a maximum thickness of 148 m. Vertical and sub-vertical fractures, associated with dolerite sills and dykes, occurring at depths >3000 m are documented in SOEKOR exploration boreholes (e.g., Leith and Trümpelmann 1967). In outcrops, two predominant mean joint orientations of 242/53 and 143/73 were encountered (Campbell 2014) and similar orientations are reported from the overlaying Permo-Triassic Beaufort sandstones studied by Senger et al (2015). Major faults in the study area northeast of East London are striking E-W (Mountain 1974;Johnson and Caston 1979).…”

Section: Geological Settingsupporting

confidence: 69%

“…These three fracture types are also present in borehole KWV-1. Outcrop data from the Ecca Pass (Campbell 2014) reveal two predominant mean joint orientations of 242/53 and 143/73 in the Permian Ripon Formation and similar orientations were measured in the Permo-Triassic Beaufort sandstones studied by Senger et al (2015). However, these authors note that open fractures decrease with increasing lithostatic pressure (depth) and are less likely good fluid conduits at depth.…”

Section: Discussionmentioning

confidence: 72%

“…4, 5e) provide a natural permeability improvement that can be enhanced by hydraulic fracturing. The influence of dykes and sills to permeability enhancement was studied by Senger et al (2015) in the Karoo Basin and demonstrates the potential for fluid-flow channelling along the intrusion-host rock interfaces. This study also highlights the different fracture…”

Section: Discussionmentioning

confidence: 99%

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Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

2016

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Section: Geological Settingsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

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Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

2016

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“…The magma plumbing systems in these basins are primarily dominated by interconnected networks of sill intrusions, the emplacement of which can significantly deform the host rock and influence petroleum system development (Kontorovich et al, 1997;Thomson and Hutton, 2004;Cartwright and Hansen, 2006;de Saint-Blanquat et al, 2006;Morgan et al, 2008;Galerne et al, 2011;Schofield et al, 2015;Magee et al, 2016;Wilson et al, 2016). For example, numerous studies have demonstrated that sill intrusions may (1) locally heat and mature organic matter within the host rock, generating oil and/or gas (e.g., Rodriguez Monreal et al, 2009), (2) be associated with 1 overlying dome structures that can be described as four-way dip closures Jackson et al, 2013;Magee et al, 2014Magee et al, , 2015, and (3) promote the development of local intense fracture networks that locally increase host rock permeability (Witte et al, 2012;Agirrezabala, 2015;Senger et al, 2015). A robust understanding of the mechanics of magma emplacement in volcanic basins is therefore required to derisk hydrocarbon exploration in volcanic basins (Potter and Konnerup-Madsen, 2003;Schutter, 2003aSchutter, , 2003b.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

et al. 2017

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The emplacement of igneous intrusions into sedimentary basins mechanically deforms the host rocks and causes hydrocarbon maturation. Existing models of host-rock deformation are investigated using high-quality 3D seismic and industry well data in the western Møre Basin offshore mid-Norway. The models include synemplacement (e.g., elastic bending-related active uplift and volume reduction of metamorphic aureoles) and postemplacement (e.g., differential compaction) mechanisms. We use the seismic interpretations of five horizons in the Cretaceous-Paleogene sequence (Springar, Tang, and Tare Formations) to analyze the host rock deformation induced by the emplacement of the underlying saucer-shaped Tulipan sill. The results show that the sill, emplaced between 55.8 and 54.9 Ma, is responsible for the overlying dome structure observed in the seismic data. Isochron maps of the deformed sediments, as well as deformation of the younger postemplacement sediments, document a good match between the spatial distribution of the dome and the periphery of the sill. The thickness t of the Tulipan is less than 100 m, whereas the amplitude f of the overlying dome ranges between 30 and 70 m. Spectral decomposition maps highlight the distribution of fractures in the upper part of the dome. These fractures are observed in between hydrothermal vent complexes in the outer parts of the dome structure. The 3D seismic horizon interpretation and volume rendering visualization of the Tulipan sill reveal fingers and an overall saucer-shaped geometry. We conclude that a combination of different mechanisms of overburden deformation, including (1) elastic bending, (2) shear failure, and (3) differential compaction, is responsible for the synemplacement formation and the postemplacement modification of the observed dome structure in the Tulipan area.

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“…In this situation, the higher permeability of the sandstone would not have allowed high pressures to build. A study in the dolerite dykes of the Karoo in South Africa identified similar chilled margins of dolerite dykes as potential fluid pathways, with the extent of fracturing associated with the hydraulic properties of the host rock (Senger et al 2015).…”

Section: Discussionmentioning

confidence: 99%

Fractures in shale: the significance of igneous intrusions for groundwater flow

MacDonald

Davies

2018

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Research in Cretaceous shales from West Africa has demonstrated that significant permeability can develop within shales at shallow depths (<100 m), equivalent to a permeability of >1 m day−1. Much of the variation in permeability is related to the degree of burial metamorphism, with shales that have been altered and that approach the anchizone having the highest permeability and those that are largely unaltered (early diagenetic zone) having the lowest permeability. However, further research targeting largely unaltered shales dominated by smectite clay has shown that the presence of small igneous intrusions can radically alter the hydrogeology. Twenty-four exploratory boreholes were drilled into smectite-dominated shale and nine of these boreholes were targeted to small dolerite intrusions within the shale. The dolerite was intensely fractured at the intrusion edge, with significant zeolite growth along the fracture surfaces. The permeability in the fractured dolerite was the highest measured in any shale borehole, with transmissivities of up to 60 m2 day−1 measured from pumping tests. Fracturing was less where dolerite was intruded into sandstones, however, and the measured transmissivity was lower (<0.5 m2 day−1). We postulate that the low permeability and high water content of the shale enabled high pressures to develop during intrusion, facilitating the development of fractures along the intrusion contact zone.

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Fracturing of doleritic intrusions and associated contact zones: Implications for fluid flow in volcanic basins

Cited by 68 publications

References 35 publications

Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

Geothermal energy from the Main Karoo Basin? New insights from borehole KWV-1 (Eastern Cape, South Africa)

Mechanisms of overburden deformation associated with the emplacement of the Tulipan sill, mid-Norwegian margin

Fractures in shale: the significance of igneous intrusions for groundwater flow

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