Rock Physics Relations Derived from Petrophysical Logs for Indus Offshore Area, Pakistan

Abstract

Conventional seismic interpretation provides subsurface geometric information, while quantitative seismic interpretation can provide lithologic and fluid information, including saturations, porosity, density, Poisson’s ratio and other elastic parameters. Rock physics is the main science behind quantitative interpretation and includes a number of transforms, in the form of empirical relations, for the computation of various rock properties. In addition, crossplot templates of these properties help in facies modeling and reservoir characterization. This paper presents rock physics transforms between compressional velocity, shear velocity, density, porosity, resistivity and gamma ray radiation for Cretaceous to Miocene strata in the Indus offshore area, Pakistan. These transforms are empirical relations established through regression analysis between various petrophysical parameters. Logs from twelve wells have been used in the analysis to give a good representation of rock properties in the area. Most of the relations have a linear correlation coefficient above 0.74 and therefore can be used reliably in quantitative interpretation of seismic data.