Dear all...

I am new student in basement fracture. I am waiting answer for this question also.

Thanks

In the subsurface the best way to understand the distribution of hydrocarbons in the basement is to analyze Resistivity image logs and diapole sonic images. This because most of the hydrocarbons are hosted in fractures and joints. Primary porosity in these rocks is almost negligible (effective porosity), most of it is secondary porosity. Good publications on characterization of such reservoirs are available from Vietnam.

Thin sections would answer two things, the primary classification of the rock and the foliations, if any are present. Both these may not have much relation with the actual occurrence ofhydrocarbons.

There are many papers from the Neuquen Basin (Argentina), either from intrusive reservoir rocks as from the basement. One of this paper is "Los reservorios de Las rocas igneas intrusivas" published in the "V Congreso de Exploración y Desarrollo de Hidrocarburos, Mar del Plata (Argentina) 2002. I couldn´t attach it because it has near 40 Mb. [email protected]

There are many differences in the way in which the reservoir performs and the porosity distribution in igneous reservoirs which are either intruded into the sediment or have been effused as a stratigraphic unit within the overall sedimentary sequence from those which form the 'Basement' for deposition (Rocks which are the technical basement over which a basin evolves). The fracture orientations (porosity) in the later is more related to the primary structural grain in these rocks overprinted by the tectonics which control the basin evolution. Migration of oil in these usually ocours when the sources juxtapose against it at deeper levels and then find an easy path of migration along the open fractures. Such reservoirs many a time have a depletion drive. On the other hand in the former, the imprint of late phase deformations in the basins, mostly low intensity tectonics, leading the induction of stress related fractures in a regime with considerable overburden stress. Determination of fracture orientations and their role in hosting the hydrocarbons is relatively simpler. (they behave in a similar manner to fractured limestone reservoirs in some cases). The drive in such reservoirs can be in all possible modes (ex depletion, gas cap expansion, and aquifer driven).

Bo