1000 m long gas blow-out pipes

Løseth, Helge; Wensaas, Lars; Arntsen, Børge; Hanken, Nils‐Martin; Basire, C.; Graue, Knut

doi:10.1016/j.marpetgeo.2010.10.001

Cited by 187 publications

(98 citation statements)

References 36 publications

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“…Gas chimneys are acoustic maskings which create dimmed and distorted amplitudes and does not show any clear stacking unlike seismic pipes which show vertical stacking of high or low amplitude anomalies (Andresen, 2012;Berndt, 2005;Løseth et al, 2011Løseth et al, , 2001Moss and Cartwright, 2010). They are described in different ways in the literature as columnar disturbances, wipeout zones, dimmed and distorted amplitudes in seismic data (Andresen and Huuse, 2011;Berndt, 2005;Heggland, 1998;Heggland et al, 1999;Hustoft et al, 2010;Løseth et al, 2009).…”

Section: Gas Chimneysmentioning

confidence: 99%

Deep-seated faults and hydrocarbon leakage in the Snøhvit Gas Field, Hammerfest Basin, Southwestern Barents Sea

Mohammedyasin

Lippard

Omosanya

et al. 2016

Marine and Petroleum Geology

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High-quality 3D seismic data are used to analyze the history of fault growth and hydrocarbon leakage in the Snøhvit Field, southwestern Barents Sea. The aim of this work is to evaluate the role of tectonic fracturing as a mechanism driving fluid-flow in the study area. To achieve this aim, an integrated approach including seismic interpretation, multiple seismic attribute analysis, fault modeling and displacement analysis was used.The six major faults in the study area are dip-slip normal faults which are characterized by complex lateral and vertical segmentation. The three main episodes of fault reactivation interpreted were in late Jurassic (Kimmeridgian), early Cretaceous and Paleocene times. Fault reactivation in the study area is mainly through dip-linkage. Throw-distance plots of the representative faults also revealed along-strike linkage and multi-skewed C-type profiles. The throw profiles show that faults in the study area evolved through polycyclic activity involving both blind propagation, syn-sedimentary activity and that they have their maximum displacement at the reservoir zone. The expansion and growth indices provide evidence for coeval fault activity with sedimentation and interaction of the faults with a free surface during their evolution.

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Section: Gas Chimneysmentioning

confidence: 99%

Deep-seated faults and hydrocarbon leakage in the Snøhvit Gas Field, Hammerfest Basin, Southwestern Barents Sea

Mohammedyasin

Lippard

Omosanya

et al. 2016

Marine and Petroleum Geology

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“…It is therefore very likely that they are part of the same vent through which fluid flowed. We therefore suggest that shallow depressions or methane-related carbonates are the surface expression of fluid flow through the chimney (HEGGLAND, 1997;HO et al, 2012) and thus define the latest phase of chimney activity, which occurred over a short length of time from hours to a few months as suggested by LØSETH et al (2011).…”

Section: Timing Of Fluid Flow Relative To Faultingmentioning

confidence: 60%

“…These characteristics are common amongst chimneys observed elsewhere in the world (cf. HEGGLAND, 2005;HUSTOFT et al, 2007HUSTOFT et al, , 2010PETERSEN et al, 2010;LØSETH et al, 2011). The stack of anomalies of Fig.…”

Section: Methodsmentioning

confidence: 99%

“…In cross-section, chimneys are vertical, narrow structures expressed in seismic data by any or one of the following: pull-up, push-down or stacked amplitude anomalies (LØSETH et al, 2001;HEGGLAND, 2005;HUSTOFT et al, 2007;PETERSEN et al, 2010), while zones of pull-up and push-down are generally interpreted as indicators for occurrences of genuine fluid conduits, i.e., hydraulic fractures on seismic (e.g., PYRAK-NOLTE, 1996;LØSETH et al, 2001LØSETH et al, , 2011HEGGLAND, 2005;HUSTOFT et al, 2010). On amplitude maps chimneys show up as small zones of amplitude anomalies (e.g., horizon 1-3 in Fig.…”

Section: Map View Geometry Of Chimneys and Pfsmentioning

confidence: 99%

“…The timing of chimneys are very ambiguous where they do not contain any syn-kinematic indicators (e.g., containing pockmarks); only a cross-cutting relationship with stratigraphy allows the earliest possible onset to be determined (cf. LØSETH et al, 2011). The latest possible timing is presentday because the chimney could have formed in a completely blind sense similar to blind faults (cf.…”

Section: Timing Of Fluid Flow Relative To Faultingmentioning

confidence: 99%

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Insights into the permeability of polygonal faults from their intersection geometries with Linear Chimneys: a case study from the Lower Congo Basin

Ho¹,

Carruthers²,

Imbert³

2016

Carnets Geol.

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Layer-bound arrays of polygonal compaction faults have long been considered as important migration routes for hydrocarbon fluids leaking to the surface across thick shale sequences. A classic example is the deep offshore of the Lower Congo Basin where numerous fluid-venting structures are present above a Pliocene polygonal fault system. In this paper we present a detailed seismic analysis of a newly recognised system of Quaternary-aged Linear Chimneys and their intersection geometries with pre-existing Pliocene-aged polygonal faults (PF). Most (73%) of the 209 chimneys analysed intersect the lower portions of polygonal faults and almost half of these are rooted in strata below the PF interval. This indicates that fluid (in this case gas) migrated vertically, cross-cutting polygonal faults as it ascended through the tier. This is a strong indicator that PFs did not provide viable migration pathways otherwise chimneys would terminate at the upper tip of the fault, which would be the most likely migration exit point. Only twice in the whole system of Linear Venting Systems did this occur. A sub-set of chimneys stems from or above PF planes but these are restricted to either the lower footwall or from the apex area of hanging wall. At best they are evidence of fluids migrating up the lower part of polygonal faults and exiting deep within the tier, then migrating through most of the tier in their own vertical leakage vents. These results provide strong indicators that at least within this part of the Lower Congo Basin polygonal faults were the least effective/favoured migration pathway and that it was more energy-efficient for migrating gas to hydrofracture its fine-grained overburden than to re-open polygonal faults.Key Words: Linear chimneys; hydrocarbon; polygonal faults (PFs); permeability; methane-related carbonates; Lower Congo Basin; Angola. Résumé : La perméabilité des failles polygonales déduite de la géométrie de leurs intersections avec des cheminées linéaires : une étude de cas dans le bassin du Bas-Congo.-Les réseaux de "failles polygonales" (failles de compaction restreintes à un intervalle stratigraphique) ont été longtemps considérés comme d'importants chemins pour la migration vers la surface des hydrocarbures à travers d'épaisses séries argileuses. Un exemple classique est fourni par l'offshore profond du bassin du Bas-Congo où de nombreuses structures d'échappement de fluides sont présentes au-dessus d'un système de failles polygonales affectant l'intervalle pliocène. Ce papier présente l'analyse sismique détaillée d'un système récemment reconnu de cheminées linéaires d'âge quaternaire, ainsi que de la géométrie de leurs intersections avec des failles polygonales pliocènes (donc préexistantes). La plupart (73 %) des 209 cheminées analysées recoupent le mur des failles polygonales, et près de la moitié d'entre elles s'enracinent dans l'intervalle sous-jacent à l'intervalle faillé. Cette disposition indique que le fluide (gaz en l'occurrence) a migré verticalement, recoupant les failles pol...

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Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers

Cai

Ofterdinger

2014

Water Resources Research

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Natural gas extracted from hydraulically fractured shale formations potentially has a big impact on the global energy landscape. However, there are concerns of potential environmental impacts of hydraulic fracturing of the shale formations, particularly those related to water quality. To evaluate the potential impact of hydraulically fractured shale on overlying aquifers, we conduct realizations of numerical modeling simulations to assess fluid flow and chloride transport from a synthetic Bowland Shale over a period of 11,000 years. The synthetic fractured shale was represented by a three-dimensional discrete fracture model that was developed by using the data from a Bowland Shale gas exploration in Lancashire, UK. Chloride mass exchange between fractures and the rock matrix was fully accounted for in the model. The assessment was carried out to investigate fluid and chloride mass fluxes before, during, and after hydraulic fracturing of the Bowland Shale. Impacts of the upward fracture height and aperture, as well as hydraulic conductivity of the multilayered bedrock system, are also included this assessment. This modeling revealed that the hydraulically fractured Bowland Shale is unlikely to pose a risk to its overlying groundwater quality when the induced fracture aperture is 200 mm. With the fracture aperture 1000 mm, the upward chloride flux becomes very sensitive to the upward fracture height growth and hydraulic conductivity of the multilayered bedrock system. In the extremely unlikely event of the upward fracture growth directly connecting the shale formation to the overlying Sherwood Sandstone aquifer with the fracture aperture 1000 mm, the upward chloride mass flux could potentially pose risks to the overlying aquifer in 100 years. The model study also revealed that the upward mass flux is significantly intercepted by the horizontal mass flux within a high permeable layer between the Bowland Shale and its overlying aquifers, reducing further upward flux toward the overlying aquifers.

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1000 m long gas blow-out pipes

Cited by 187 publications

References 36 publications

Deep-seated faults and hydrocarbon leakage in the Snøhvit Gas Field, Hammerfest Basin, Southwestern Barents Sea

Deep-seated faults and hydrocarbon leakage in the Snøhvit Gas Field, Hammerfest Basin, Southwestern Barents Sea

Insights into the permeability of polygonal faults from their intersection geometries with Linear Chimneys: a case study from the Lower Congo Basin

Numerical assessment of potential impacts of hydraulically fractured Bowland Shale on overlying aquifers

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