Abstract: Permeability is one of the most important factors in influencing the commercial viability of a hydrocarbon reservoir. So far, permeability cannot be measured directly in-situ in reservoir formations. This invention relates to the field of estimating in-situ permeability of the reservoir rock formations. The measurements can be made across two wells or in a single well. Due to the morphology of their pore interconnections and the pore fluids in the rock, permeable rocks are elastically nonlinear. In a permeable rock, which is elastically nonlinear, the interactions between two elastic waves can be used in a unique way to map its physical properties. In this invention, the interaction of an elastic wave generated within the permeable rock with an externally generated seismic signal is used to determine the bulk tortuosity and bulk permeability of a reservoir rock formation.

Abstract: Elastic nonlinear effects, which cause frequency spectral broadening and the effects of the presence of the Slow-Wave in the reservoir rocks, are investigated. The creation of new frequencies due to elastic nonlinearity of the reservoir rocks and their presence in the reflected seismic signals is used to map the location and extent of the reservoir formations. The large differences in the velocities of the Compressional Wave and the Slow-Wave cause changes in their reflection and refraction characteristics. The reflection due to Slow-Wave appears as a low-frequency artifact, delayed in time. The delay time of this artifact is used to calculate the Slow-Wave velocity and the tortuosity of the reservoir rocks. Based on the tortuosity and the wellbore data, permeability can be estimated.

Abstract: 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 ‘carrier’ wave during the compression and rarefaction cycles of the ‘modulation’ signal is recorded.

Abstract: This invention relates to mapping the open fractures in the reservoir subsurface formations. To map these open fractures, the elastically nonlinear interaction of the two surface generated seismic waves, as they propagate through the open fractures and are reflected back from the subsurface boundaries, is recorded using conventional 3-D seismic receiver configurations. Recorded data are processed for standard 3-D reflection imaging and additionally for mapping the location and orientation of the subsurface open fractures.

Abstract: This invention relates to mapping the hydrocarbon reservoir characteristics by mapping the reservoir formations that display dynamic elastic nonlinearity responses to the seismic signals. The main reason of this nonlinear behavior in the reservoir rocks is their bulk rock property: the porosity, fractures, differential pressure and pore saturation. To map these bulk rock properties, the interaction of the two seismic waves as they propagate through elastically nonlinear rocks is recorded. Two compressional seismic signals are transmitted from the surface. Seismic reflection data using surface or borehole detectors are recorded. One of the transmitted signals is a conventional swept frequency and the other is a mono-frequency signal. During the propagation of these two signals through the elastically nonlinear reservoir rocks, there is an interaction between the two signals. The sum and difference frequencies of the two primary seismic signals that were transmitted from the surface are created.

Abstract: 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.

Abstract: This Patent describes a method for determining the location and orientation of the open natural fractures in an earth formation by analyzing the interaction of the two seismic signals. One is a low frequency signal transmitted from the earth's surface and the other a high frequency signal transmitted from a wellbore. The compressional and the rarefaction cycles of the lower frequency signal are used to modulate the width of the open fractures, which changes their transmission characteristics. As a result, the amplitude of the high frequency signal gets modulated as it propagates through the open fractures. The result of the interaction of the high and low frequency seismic signals is recorded in another wellbore. The spectral analysis of the modulated signal that is recorded during compression and rarefaction cycles of the lower frequency surface generated signal is used to determine the location and the orientation of the open natural fractures.