Hydrates Offshore Brazil

Fontana, Rogerio Luiz; Mussumeci, Alexandre

doi:10.1111/j.1749-6632.1994.tb38827.x

Cited by 22 publications

(16 citation statements)

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“…The presence of widespread BSRs in the Rio Grande Cone, Pelotas Basin, was previously reported by Fontana (1989), Fontana and Mussumeci (1994), Sad et al (1997) and Sad et al (1998), suggesting the presence of gas hydrate deposits in a large portion of the cone area covering nearly 45,000 km 2 within water depths of 500 m to 3,500 m. Despite such indications, the Rio Grande Cone remained unexplored for many years thereafter. A more recent time-frequency spectral signature study performed by Oliveira et al (2010) in seismic lines from the Rio Grande Cone associated spectral anomalies to the possible occurrence of gas hydrate accumulations above the BSR and free gas zones, gas flux features and gas reservoirs below the BSR.…”

Section: Accepted Manuscriptmentioning

confidence: 71%

“…Gas hydrate deposits may be present at or near the base of the GHSZ in the Rio Grande Cone as suggested by the presence of ubiquitous world-class BSRs in the area (Sad et al, 1998;Fontana and Mussumeci, 1994;Clennell, 2000;Oliveira et al, 2010). Such pervasive BSRs are a substantial indication that free gas should be present in the sediments immediately below the GHSZ, having possibly migrated vertically through deep-seated faults (Fig.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 92%

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Natural gas hydrates in the Rio Grande Cone (Brazil): A new province in the western South Atlantic

Miller

Ketzer

Viana

et al. 2015

Marine and Petroleum Geology

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Section: Accepted Manuscriptmentioning

confidence: 71%

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 92%

Natural gas hydrates in the Rio Grande Cone (Brazil): A new province in the western South Atlantic

Miller

Ketzer

Viana

et al. 2015

Marine and Petroleum Geology

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“…This may explain occurrences of anomalously low seismic velocity (less than 1.5 km s -1) within the hydrate stability zone at continental margins [Fontana and Mussumeci, 1994;Rowe et al, 1995]. Certain instances of marked seismic attenuation (blanking) that are not accompanied by a commensurate increase in sonic velocity [Wood et al, 1994; W. Wood personal communication, 1998], and so are not easily explicable simply as zones of hydrate precipitation, may also be related to changes in sediment physical properties during water depletion.…”

Section: This Issue]mentioning

confidence: 99%

Formation of natural gas hydrates in marine sediments: 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

Clennell¹,

Hovland²,

Booth³

et al. 1999

J. Geophys. Res.

607

511

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Abstract. The stability of submarine gas hydrates is largely dictated by pressure and temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of deep marine sediments may also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our conceptual model presumes that gas hydrate behaves in a way analogous to ice in a freezing soil. Hydrate growth is inhibited within finegrained sediments by a combination of reduced pore water activity in the vicinity of hydrophilic mineral surfaces, and the excess internal energy of small crystals confined in pores. The excess energy can be thought of as a "capillary pressure" in the hydrate crystal, related to the pore size distribution and the state of stress in the sediment framework. The base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature (nearer to the seabed) than would be calculated from bulk thermodynamic equilibrium. Capillary effects or a build up of salt in the system can expand the phase boundary between hydrate and free gas into a divariant field extending over a finite depth range dictated by total methane content and pore-size distribution. Hysteresis between the temperatures of crystallization and dissociation of the clathrate is also predicted. Growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, and lenses in muds; cements in sands) can largely be explained by capillary effects, but kinetics of nucleation and growth are also important. The formation of concentrated gas hydrates in a partially closed system with respect to material transport, or where gas can flush through the system, may lead to water depletion in the host sediment. This "freezedrying" may be detectable through physical changes to the sediment (low water content and overconsolidation) and/or chemical anomalies in the pore waters and metastable presence of free gas within the normal zone of hydrate stability.

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“…Os refletores BSR já foram registrados em estudos geofísicos na margem continental brasileira, na Foz do Amazonas no norte (Sad et al, 1998) até a Bacia de Pelotas no sul (Fontana & Mussumeci, 1994). Provavelmente, os hidratos de gás ocorrem em muitas outras áreas, desde que haja uma quantidade suficiente de metano biogênico e termogênico.…”

Section: A Perspectiva Brasileiraunclassified

Hidrato de gás submarino: natureza, ocorrência e perspectivas para exploração na margem continental brasileira

Clennell¹

2000

Rev. Bras. Geof.

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Hidrato de gás, ou clatrato é um sólido cristalino sendo composto de água e gases de peso molecular pequeno. Os hidratos de metano são abundantes em sedimentos submarinhos nas margens continentais. A distribuição dos clatratos pode ser mapeada através de perfilagem sísmica, perfis de poço, e amostragem geoquímica. A quantidade estimada de hidratos de gás submarino no mundo equivale aproximadamente a duas vezes o total de todos os recursos convencionais de óleo e gás. Entretanto, a exploração de hidratos de gás submarino como fonte de energia ainda não é viável em termos técnicos ou econômicos. Deslizamentos de grandes proporções podem ser desencadeados pela dissociação dos hidratos. O gás liberado durante um evento dessa natureza pode entrar na atmosfera, estimulando o efeito estufa. O talude continental do Brasil mostra em várias localidades assinaturas geofísicas da presença de hidratos de gás, e isto não é incomum, uma vez que as condições geológicas adequadas para a formação deste mineral são encontradas em outras áreas da margem continental. Apesar da existência de recurso como os hidrocarbonetos não-convencionais em águas brasileiras, esses também apresentam um risco desconhecido quanto às operações de exploração e de produção em campos de óleo e gás já em desenvolvimento em águas profundas. Palavras-chave:Hidrato de gás; Margem continental; Geoquímica orgânica; Recursos marinhos. SUBMARINE GAS HYDRATES: NATURE, OCCURRENCE & PERSPECTIVES FOR EXPLORATION IN THE BRAZILIAN CONTINENTAL MARGIN -

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Hydrates Offshore Brazil

Cited by 22 publications

References 0 publications

Natural gas hydrates in the Rio Grande Cone (Brazil): A new province in the western South Atlantic

Natural gas hydrates in the Rio Grande Cone (Brazil): A new province in the western South Atlantic

Formation of natural gas hydrates in marine sediments: 1. Conceptual model of gas hydrate growth conditioned by host sediment properties

Hidrato de gás submarino: natureza, ocorrência e perspectivas para exploração na margem continental brasileira

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