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Nonlinear Seismic Imaging, Inc.

Sofia Khan McGuire

Tawassul Ali Khan

A method for determining the location and the orientation of the open natural fractures in an earth formation from the interaction of the two seismic signals, one signal transmitted into the formation from one wellbore and the second signal transmitted from the surface of the earth, the interaction of the two seismic signals as they simultaneously propagate through the fractured space is recorded in the second wellbore. The seismic signal transmitted from the surface is a lower frequency acoustic pulse of large amplitude identified as 'modulation' wave and the signal transmitted from the wellbore is a higher discrete frequency seismic signal, identified as 'carrier' wave. The interaction of the &lsquo;carrier&rsquo; wave during the compression and rarefaction cycles of the &lsquo;modulation&rsquo; signal is recorded. By subtracting the &lsquo;carrier&rsquo; from the interaction signal, the &lsquo;modulation-pulse&rsquo;, which represents the arrival time of the surface generated acoustic pulse, from the surface source to the subsurface fractures is extracted. By plotting the arrival times and the relative amplitudes of the &lsquo;modulation-pulse&rsquo;, the orientation and the location of the open fractures is determined.

Mapping subsurface open fractures in a reservoir using a surface impulse and a downhole vibratory source

This invention relates to using elastically nonlinear seismic imaging methods, to identify the bypassed hydrocarbons and the movement of the reservoir fluids in the reservoir due to injection and production processes. Time-lapse seismic recording is used to monitor the changes in the hysteretic nonlinear behavior of the pore fluids in the reservoir rocks. Since the nonlinear hysteretic behavior of the saturated reservoir rock generates harmonics of the primary seismic signal that propagates through it, the measurement of these harmonics is used to determine the changes in the reservoir fluids due to hydrocarbon production over time.

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Houston, TX, United States of America

Sofia Khan McGuire