Browsing by Author "Obeng-Manu, Obeng-Manu"

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    Lithology and pore fluid prediction of a reservoir using density, compressional and shear wave logs: a case study of the Tano basin
    (July, 2015) Obeng-Manu, Obeng-Manu
    Due to the higher uncertainties associated with the traditional method of determining lithology and pore fluid using well logs, quantitative rock physics analysis was carried out to determine the lithology and pore fluid of a reservoir in the Tano Basin. Inaccurate prediction of lithology and pore fluid, results in the inaccurate determination of other petrophysical properties such as porosity, permeability, net pay, etc. Rock physics analysis reduces the uncertainties related to the traditional method of predicting lithology and pore fluid. The primary objective of this thesis is to predict lithology and pore fluid using rock physics analysis, however, the oil-water-contact (O.W.C) and reservoir zone were also predicted. In this thesis, density, compressional wave velocity and shear wave velocity logs were used as input to calculate elastic parameters such as velocity ratio, Poisson’s ratio, and Lamé parameters. The calculated velocity ratio log was used to differentiate between sand and shale. Rock physics analysis of the calculated Lamé parameters was used for comprehensive lithology prediction. A crossplot of Lamé’s ratio (λ/μ) and difference (λ*⍴ - μ*⍴) using Goodway (2001) interpretation template was carried out. The gas sand, wet sand, and carbonate formations were delineated according to the crossplot analysis. Poisson’s ratio and velocity ratio crossplot was also used to determine the pore fluid content. Oil sand, gas sand, and brine sand were predicted from the crossplot analysis. Oil-water-contact and reservoir zone were identified due to the rapid variations observed in the velocity ratio log. This thesis demonstrates how rock physics analysis can be used to improve lithology and pore fluid prediction of the Tano Basin.