Controls on the Seismic Espression of Gas Hydrates in Marine Settings
M. Paganoni, J. Cartwright, M. Foschi, P. Van Rensbergen and C. Shipp
Event name: EAGE Shallow Anomalies Workshop
Session: Shallow Geophysical Anomalies, Hydrocarbon Migration and Seepage
Publication date: 23 November 2014
Info: Extended abstract, PDF ( 1.75Mb )
Price: € 20
The presence of gas hydrates in natural environments was originally inferred thanks to the identification of a bottom simulating reflector (BSR), representing the base of the gas hydrate stability zone (BGHSZ). Even if the stability condition necessary to allow hydrates formation are present in a huge portion of ocean sediments, their distribution in the sedimentary basins appear to be patchy, even at the seismic scale. The aim of this paper is to synthesize the seismic evidences of the gas hydrates habitat, mainly using published data and a case study, in order to re-define the factors affecting the hydrate occurrence at the seismic scale. The seismic expression of several hydrate provinces often lacks a proper BSR. On the other hand, hydrate distribution appear to be connected with the underlying hydrocarbon system, able to concentrate fluid flow through different pathways, as well as strongly conditioned by the host lithology. In addition, the variation of P, T through time, due to e.g. erosion, uplift and climate changes imply that the BGHSZ is a dynamic boundary. These considerations have severe implication for the exploration of hydrate reservoirs, frequently characterized by patchy/discontinuous BSR and hydrocarbon leaking structures.