A Fractal Model for the Vertical Distribution of Sands in the Perales Oil Fields in the Basin of Golfo San Jorge (Argentina)

摘要

The irregularity and discontinuity that the sands present in thernvertical sections of the Bajo Barreal Formation lead us to thernconcept that these sands present a difficult and chaoticrndistribution. The tuning effects and lack of resolution of thernseismic information leads us on a search for new models andrnmethodologies to find a model for the distribution of thesernsands. The objective of this work is to demonstrate the fractalrnbehavior of the sets of sands, and the need to keep thisrnproperty in mind for any type of geostatistical analysis, sincernthese types of analysis generally assume a normal distributionrnof the data population in opposition of the fractal concept.rnThe term fractal was first defined in 1975 by BenoitrnMandelbrot to describe the geometry of those objects whichrnhave an extremely irregular shape, interrupted and fragmented,rnand continue being so at any scale chosen for study. Thernfractal dimension (D) allows us to quantify the degree ofrnirregularity of a geometrical set or of a natural object. Anrnimportant consequence of this scale exponent is that arnpopulation of objects that respond to a fractal distribution willrnnot have average values of its properties, being able to speakrnonly of the distribution of sizes, of which a specific object orrnphenomenon occurs within a specific interval of time or space.rnAn important concept is that the fractal behavior only occursrnwithin a range of scales in nature, and no natural object isrnindefinitely fractal.rnThe punctuated behavior of the sedimentation brings, as arnconsequence, the distribution of the sands presented in arndiscontinuous form, and for that reason describable from arnfractal viewpoint. Based on these observations, there is a needrnto characterize the population of sands in the Bajo BarrealrnFormation as a fractal set. Likewise, these results of thernsubsurface have been verified with data from outcroppings,rnhaving obtained similar results. The fractal vision hasrncontributed to the discrimination of parasequences, thernrecognition of a distribution model of the sands, and thernconclusion that the most important problems in these oil fieldsrnare the pathways of migration and trapping of hydrocarbonsrnand not the presence of sands as was previously assumed.