1964 Paper I

THE INTERPRETATION OF THE FRACTURE FINDER MICRO-SEISMOGRAMSM LOG

by

Terry Walker, A Division of Halliburton Company

ABSTRACT

The extreme variation of the wave form patterns on the Micro-SeismogramSM Log presentation of the acoustic signal has led to efforts to more fully determine the conditions giving rise to these variations. Since the receiver signal is the algebraic sum of all arrivals within a given period of time, the time or arrival and phasing conditions should give information regarding the bulk coupling within the formation. Postulations on causes of reflection patterns on field logs led to calculations of formation velocity effects on such patterns. The shape of the reflections were found to be in agreement with actual formation velocities.

Further speculations led to the creation of synthetic Micro-Seismogram Logs by mixing oscillator signals in a manner designed to agree with the field patterns. These synthetic Micro-Seismogram Logs show characteristic patterns which can be used to interpret field logs.

A further part of the study was the logging of a shallow test hole before and after fractures were induced. The changes in wave forms and the patterns resulting from induced horizontal and vertical fractures are in agreement with the characteristics previously discussed.