Abstract

Measurement of geomechanical properties using seismic and laboratory methods have been used in oil and gas industry for several years. Laboratory methods, in most cases, take only small samples from consolidated rocks, which may not be representative of the elastic regime existing in the reservoir owing to sample size. In general, geomechanical studies are performed on a well-by-well basis. Measurements calculated at the wellsite are then used as calibration points to convert the 3-D seismic data to geomechanical cube. However, elastic properties measured this way are restricted to the well location and cannot be interpolated across the reservoir. To overcome these challenges, this paper describes an approach for deriving and discretizing geomechanical and other elastic properties in the reservoir by integrating results of 3D geo-cellular and basin models.

The workflow presented in this paper is utilized to calculate cell-by-cell elastic properties of the reservoir by integrating parameters from both basin model and 3D geo-cellular grid. The basin model reconstructs the geologic history (i.e. burial history) by back-stripping the reservoir to its original depositional thickness. Through this reconstruction, the mechanical compaction, pore pressures, effective stress, and porosity-vs-depth relationships are established for the reservoirs. In the final stage, dicretized calculations of geomechanical properties are assigned to each lithotype (facies) in the geomodel. The discretization of elastic properties into 3D grids resulted in better understanding of the prevailing rock elastic properties and stress regimes helping hydraulic fracturing operators in the effective design of their depletion strategies with minimal drilling risks and costs. This approach provides an innovative way of determining effective minimum horizontal stress for the entire reservoir through distribution of elastic properties in a 3D grid. The conventional approach of using small sample plugs is not sufficient to describe elastic properties for an entire reservoir and can be replaced by current approach.

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