Mapping permeable reservoir formations by measuring the elastic nonlinear interactions of a seismic wave as it propagates through the reservoir rock matrix and its pore fluids
First Claim
1. A new method for determining the in-situ Slow-wave or Drag-wave velocity, both these waves representing the same phenomenon, of permeable reservoir rock formations which are continuous between two wellbores, and from that determination, using the existing known mathematical relationship to calculate the bulk tortuosity of the interconnected pores of reservoir rock, and estimating the bulk permeability of a reservoir formation between seismic transmitters and seismic receivers, the method comprising:
- Transmit a mono-frequency signal generated by a seismic transmitter or seismic transmitters in a wellbore and received by a seismic receiver or seismic receivers in another or the same wellbore, spectrally analyzing said received signals, determining the presence of the Drag Wave by determining the presence of the frequency side lobes of the Primary seismic wave, of a selected discrete frequency, the frequency side lobes in the said spectrum of the received signals being created by the nonlinear elastic interaction of the Primary mono-frequency seismic wave with the Drag Wave, the Drag Wave being generated through solid/liquid coupling as the Primary Compressional Wave propagates through a permeable reservoir formation between two wells, and the said formation has fluid-filled interconnected pores.
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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.
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Citations
7 Claims
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1. A new method for determining the in-situ Slow-wave or Drag-wave velocity, both these waves representing the same phenomenon, of permeable reservoir rock formations which are continuous between two wellbores, and from that determination, using the existing known mathematical relationship to calculate the bulk tortuosity of the interconnected pores of reservoir rock, and estimating the bulk permeability of a reservoir formation between seismic transmitters and seismic receivers, the method comprising:
Transmit a mono-frequency signal generated by a seismic transmitter or seismic transmitters in a wellbore and received by a seismic receiver or seismic receivers in another or the same wellbore, spectrally analyzing said received signals, determining the presence of the Drag Wave by determining the presence of the frequency side lobes of the Primary seismic wave, of a selected discrete frequency, the frequency side lobes in the said spectrum of the received signals being created by the nonlinear elastic interaction of the Primary mono-frequency seismic wave with the Drag Wave, the Drag Wave being generated through solid/liquid coupling as the Primary Compressional Wave propagates through a permeable reservoir formation between two wells, and the said formation has fluid-filled interconnected pores. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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