A Method for Determining the Hydraulic Permeability of Rocks in a Subsurface Region

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This invention describes a geophysical method for accurately determining the hydraulic permeability of rocks in underground (subsurface) regions. The method involves using seismic data to measure properties like seismic wave velocities at various locations, collecting representative rock samples for laboratory measurement of porosity and permeability under controlled stress, and then using analytical models to compute the permeability across wide areas, even between wells. This approach integrates physical measurements, rock mechanics, and mathematical modeling to map and predict fluid flow properties in subsurface geological formations without relying solely on direct sampling.

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• Oil and gas reservoir evaluation and development planning
• Geothermal energy exploration and resource assessment
• Design, monitoring, and safety analysis of underground fluid or gas storage facilities (e.g., CO2 sequestration)
• Underground water reservoir and aquifer mapping
• Site selection and design of subsurface waste disposal
• Geotechnical assessment for tunneling or underground construction
• Environmental hydrogeology, such as contaminant transport prediction

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• Provides high spatial resolution and accuracy for permeability determination compared to conventional methods
• Reduces the need for extensive drilling and direct sampling, lowering costs and minimizing environmental impact
• Enables estimation of fluid flow properties in regions between and beyond boreholes
• Non-invasive or minimally invasive when using mostly geophysical (e.g., seismic) data
• Improves reservoir management, leading to more efficient resource extraction or injection operations
• Supports safer and better-informed decisions for underground storage and waste isolation
• Can be adapted for various rock types and complex geological settings

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Patent Abstract

An exemplary embodiment of the invention relates a method for determining hydraulic permeability of rocks in a subsurface region, the method comprising: in-situ measuring and/or calculating at least one of independent seismic velocities of rocks at different locations in said subsurface region; determining at least one lithological unit in said subsurface region based on the measured seismic velocities; for the at least one lithological unit, acquiring at least one rock sample at an at least one location of said subsurface region; measuring the rock-sample porosity and permeability as functions of stress; measuring and/or calculating of at least one of independent seismic velocities of said at least one rock sample as functions of stress; computing the stiff and compliant porosity of said at least one rock sample; computing numerical coefficients of a given analytical permeability model based on the stiff and compliant porosities; computing coefficients of a given analytical model of an elastic-compliance characteristic of the rock based on the stiff and compliant porosity; computing the stiff and compliant porosity for a plurality of other locations in said subsurface region; and computing the permeability of rocks belonging to said at least one lithological unit, for said at least one location in said subsurface region and for said plurality of other locations in said subsurface region.