Patent ID: 6646437
Filing Date: 2003-11-11
Classification: G01N,G01V

Abstract:
A method for determining petrophysical properties of geologic formations containing clay materials, comprising:(a) providing a model of the geologic formation, said model comprising a wetness parameter for that fraction of the characteristic volume of adsorbed water in a given mineralogy component, which is proportional to the volume Vclay of that component; (b) providing log data corresponding to the geologic formation; (c) performing constrained inversion of the provided data log using the model of the geologic formation; and (d) determining petrophysical properties of geologic formations based on the provided model and the performed constrained inversion, wherein step (d) comprises determining a generic log of the formation according to: LOG=&Sum;i=1log&it;â€ƒ&it;s&it;â€ƒ&it;(Vmat*LOG&it;â€ƒ&it;mati+&Sum;j=1clay&it;â€ƒ&it;Vclj*LOG&it;â€ƒ&it;clij+phie*LOGi&it;w)where, LOG is the generic log, the i-index runs over the different logs available, such as gamma, bulk density, thermal neutron and NMR; Vmat is the matrix volume; Vclj is the volume of the j-th clay mineral and the clay index j corresponds to a typical clayey sandstone consisting of quartz and other minerals and common sedimentary clays, Phie represents pores of all sizes containing water in bulk form; LOGmat, LOGclij and LOGiw are the corresponding log parameters for the matrix, clay and bulk water respectively.