Application of marine geophysics to hydrocarbon reservoir characterisation

Abstract

Understanding the influence of clay distribution on the joint elastic and electrical properties of reservoir sandstones, and pressure dependence, is of great importance to hydrocarbon exploration, reservoir monitoring, and characterisation. It is well known that the presence of assemblages of clay mineral particles in a sandstone, often with their own porosity (i.e. shale), can influence both remotely sensed geophysical properties, such as seismic velocity and electrical resistivity, and reservoir properties, such as porosity and permeability. Clay distribution effects in sand-clay mixtures, and by analogy in shaly sandstones, are also well appreciated. Marion et al. (1992) showed how seismic velocity is controlled by shale content and distribution in the continuum from clean sand, through shaly sands (i.e. pore-filling shale) and sandy shales (i.e. load-bearing shale), to shale. However, there have been few observational studies of the joint properties of shaly sandstones and the effect of shale content and distribution, needed to validate theoretical models that could be used for joint inversion and interpretation of co-located seismic and electromagnetic survey data.
Carbonate rocks play an important role as subsurface hydrocarbon and water reservoirs, and are the main source of cement for concrete and buildings. Understanding the physical properties of carbonates, including the role of microstructures, is thus pertinent to many different specialised fields, such as rock physics, hydrology, geotechnical engineering, tectonics, and is essential for a better characterisation of reservoir resources. Carbonate rocks have complex geochemical, textural and petrophysical properties (most importantly for reservoir rocks, porosity and permeability), which result from the nature of their geological formation (from bioclasts, ooids, etc.) and subsequent diagenetic processes that commonly alter their mineralogy and pore networks.

This project seeks to study the inter-relationships among the elastic and electrical properties of typical sedimentary reservoir for improved insight into wave propagation phenomena in porous rocks.

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