Patent ID: 7398158

Claim:
A method of detecting fractures in a fractured zone in an Earth formation comprising the steps of: a. propagating a plurality of acoustic waves through the fractured zone so that the plurality of acoustic waves reflect off a horizon in the formation; b. receiving a plurality of seismic traces representative of the acoustic waves propagating through the fractured zone wherein a first portion of the seismic traces corresponds to a first window located above the fractured zone in the formation, and a second portion of the seismic traces corresponds to a second window located below the fractured zone in the formation; c. generating a first frequency spectrum associated with the first portion of the seismic traces corresponding to the first window; d. generating a second frequency spectrum associated with the second portion of the seismic traces corresponding to the second window; e. superimposing the first frequency spectrum onto the second frequency spectrum, thereby generating a superimposed frequency spectrum, and defining from the superimposed frequency spectrum a low frequency and a high frequency; f. when the low frequency and the high frequency is defined, further defining from the superimposed frequency spectrum a plurality of amplitude values, the plurality of amplitude values including: an amplitude Fa(high) of the first frequency spectrum at the defined high frequency, an amplitude Fa(low) of the first frequency spectrum at the defined low frequency, an amplitude Fb(bigh) of the second frequency spectrum at the defined high frequency, and an amplitude Fb(low) of the second frequency spectrum at the defined low frequency; g. from the plurality of amplitude values, defining a t* attribute by subtracting the natural log of the ratio of Fa(low) to Fb(low) from the natural log of the ratio of Fa(high) to Fb(high) to get a numerator and dividing the numerator by a denominator which comprises the defined high frequency less the defined low frequency; and h. plotting the t* attribute.