UPSCALING OF WELL LOG DATA FOR A TRANSVERSE ISOTROPIC EFFECTIVE MEDIUM

Abstract

We develop two methods to determine; (1) net to gross and hydrocarbon saturation in a mixture of sand and shale. (2) effective properties versus tilt in sand. Backus (1962) and Schoenberg and Muir (1989) averaging are used for the horizontally layered transversely isotropic medium with vertical symmetry axis (VTI), horizontal symmetry axis (HTI) and tilted symmetry axis (TTI) test respectively. A mixture of two points representing sand and shale are picked from Intrabasalt 2 formation (North Sea data) and the effective properties and anisotropic parameters (epsilon, delta and gamma) are computed using matlab algorithm. The modeling results for the VTI, HTI and TTI show that P- wave velocity (Vp ) increases with increasing net to gross and S- wave velocity (Vs ) decreases with increasing net to gross. The anisotropic parameters decrease with increasing net to gross. In the second part, the whole Intrabasalt 2 formation is considered as sand in a tilt form. The modeling results show that P- wave velocity and S- wave velocity increase with increasing tilt angle in sand and the anisotropic parameters of the tilt sand decrease with increasing tilt angle with the exception of anisotropic parameter delta which increases with tilt angle up to 30 degrees and then decreases with increasing tilt angle up to 90 degrees.