Patent ID: 7700910
Filing Date: 2010-04-20
Classification: G01V

Abstract:
1. A method for determining formation density in a region in the vicinity of a borehole wall by producing a compensated density log by logging a borehole using a density logging device, the method including irradiating the region using a source of gamma radiation and detecting using near-spaced and far-spaced radiation detectors for obtaining a density derived from near and far density values obtained from the outputs of the near-spaced and far-spaced detectors, the method comprising the steps of: (i) compensating the far density values using a programmable computer by adding a correction at a given point in a density log wherein: in which k is said first function of penetration ratio; and in which k′ is said second function of penetration ratio, “far density difference” at a given point in the density log is the difference between the far density filtered by a long filter, and the logged far density; and “near density difference” at a given point in the density log is the difference between the near density filtered by the long filter, and the logged near density; wherein the value of the second correction is not zero; and (ii) producing the compensated density log derived from said previous steps.