Patent ID: 9557440
Date: 2017-01-31
CPC Classifications: E21B,G01V

Claim:
1. A method of evaluating an earth formation intersected by a borehole, the method comprising: using an acoustic transmitter to generate acoustic signals at a frequency producing a resonance of fluid wherein said resonance generates a velocity of the fluid in the borehole and a velocity of the formation at an interface between the fluid and the formation such that a difference between the velocity of the fluid in the borehole and the velocity of the formation is dependent upon permeability of the formation; and making a first measurement of the fluid velocity; making a second measurement of the velocity of the formation; making a third measurement indicative of an electric charge on a wall of the borehole taken at the frequency; and using a processor to estimate an electroacoustic constant of the earth formation using the first measurement, the second measurement, and the third measurement.