Browsing by Subject "linear model regression"

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The influence of lithology on permeability values determined by Wyllie and Rose relation
(2010) Malureanu, Ion; Marinoiu, Cristian; Boaca, Tudor
The main reservoir properties that define a petroleum field are: bed thickness of reservoir, area, porosity, hydrocarbon saturation and permeability. Excepting permeability, the other ones can be determined accurately from well log data. Permeability is a measure of the ease with which a formation permits a fluid to flow through it. In order to be permeable, a rock must have interconnected porosity (pores, vugs, capillaries, fissures, or fractures). Multiple processes of sedimentation and diagenesis can create complex and variable pore systems and their morphology depends on the mineralogical composition, structure and texture of the reservoir. The multitude of factors which influence the permeability make them difficult to determine, based on the correlations with others petrophysic properties, obtained from well log (porosity, irreducible water saturations etc.). Such correlations have represented a major concern for many reservoir engineers and geophysicists (e.g. Kozeny, Wyllie & Rose, Tixier, Timur, Coates, etc). A good porosity - permeability correlation for different lithologies was obtained by Chilingarian. The results showed a considerable improvement in permeability estimation that was also obtained by Herron (1987) with a relation adjusted after Kozeny-Caraman in which he introduced the same coefficients dependent on texture and mineralogical composition. Therefore, we may remark that introducing lithology in the relations for permeability estimation leads to the improvement of permeability determination based on correlations. The aim of this paper consists in establishing the coefficients from Willy and Rose in function of lithology using experimental determinations on sand, siliceous sandstone, calcareous sandstone and limestone samples. In order to materialise this objective, we used linear models of regression, obtained from the linearization of Willy and Rose relation. With these models, the authors can obtain a confidence interval up to 95%. In the end of the paper, the authors propose new relations for permeability evaluation for these lithologies, and also new proceeding of calculus for other lithologies.