Allen L Howard

US Patent:

53550889, Oct 11, 1994

Filed:

Apr 16, 1991

Appl. No.:

7/686099

Inventors:

Allen Q. Howard - Kingwood TX

Assignee:

Schlumberger Technology Corporation - Houston TX

International Classification:

G01V 318

US Classification:

324339

Abstract:

A system receives output signals from a well tool disposed in a wellbore and generates a set of invasion parameters associated with a transition zone of a formation traversed by the wellbore, the parameters being used to plot a more accurate resistivity log on an output record medium. The invasion parameters include Rxo, the flushed zone resistivity; Rt, the uninvaded zone resistivity; and two other parameters not previously known, the "w" parameter and the "N" parameter, where "w" represents the midpoint of the transition zone region on the resistivity log and "N" represents a value related to the slope of the resistivity log in the transition zone region. Given the four parameters, Rxo, Rt, w, and N, a more accurate and improved resistivity log is illustrated on an output record medium, one which reflects a gradual, and not an abrupt, change in the resistivity in the transition zone portion of the log.