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STATE OF THE ART OF GAS HYDRATE

OCCURRENCES ALONG THE BRAZILIAN

CONTINENTAL MARGIN

José Antonio Cupertino
Adolpho Herbert Augustin
Luiz Frederico Rodrigues
João Marcelo Medina Ketzer
Adriano Roessler Viana
Dennis James Miller

1. Introduction

Gas hydrates are solids with a crystalline gas molecule (BOHRMANN; TORRES, 2006).
structure of the clathrate family (from the Thus, without the support of the trapped
Latin clatratus = cage), formed by an external molecules, when the water molecule thaws,
structure of water molecules (similar to the the structural grid collapses, releasing wa-
structure of ice) that trap a gas molecule in- ter and gas. For its stability, an environment
side (Figure X1). Gas hydrates are not chem- of low temperature and high pressure is re-
ical compounds, as there is no molecular quired, conditions easily found near the sea-
bond between the water molecule and the floor in the oceans.

Figure X1: Schematic
representation of methane
hydrates. The methane
molecule, CH4, (in shades
of gray) is “trapped” in a
“cage” of solid water, whose
molecules (blue spheres) are
held together by hydrogen
bonds (traces in black).

Source: Chang, (2010)

622 BLUE ECONOMY State of the Art of Gas Hydrate Occurrences 623
State of the Art of Gas Hydrate Occurrences 623