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Geodynamics and Basin Studies

Seismic waveform inversion from fracture parameters

The project deals with seismic waveform inversion for fracture parameters. The principal aim is to develop methods for improved seismic fracture characterization based on a combination of methods for full seismic waveform inversion with anisotropic effective medium theory. A further aim is to investigate some of the waveform inversion methods developed in this project which can also be applied to conventional (unfractured) reservoirs.

A large percentage of the worlds remaining hydrocarbon reserves are associated with fractures, either in the context of naturally fractured (carbonate or tight sandstone) reservoirs or unconventional resources like gas shales. Fractures are also relevant for CO2 sequestration and geothermal energy. Fractures can have a significant effect on seismic wave propagation and fluid flow, suggesting that it may be possible to derive information about fracture parameters related to permeability from seismic data alone or in combination with production data. Since fractures tend to have a preferred orientation, anisotropy effects are important in this context.

The principal aim of this project is to investigate if an improved characterization of fractured reservoirs can be obtained via a combination of waveform inversion methods and anisotropic effective medium theory. By improved, we mean that one can use the Born approximation or scattering theory beyond the Born approximation to determine all the different fracture parameters (e.g., fracture density, orientation and aperture) that determine the effective permeability tensor and also deal with multiple fracture sets and production-related effects of stress and pore fluid pressure for weak and strong contrasts.

A further aim is to investigate if some of the waveform inversion methods developed in this project also can be used for seismic imaging and characterization of conventional (unfractured) reservoirs. We also expect that an interaction of this project with related projects dealing with the characterization of fractured reservoirs using electromagnetic and/or production data may lead to additional spin-off results within joint inversion.

Researchers working on this project

Ingjald Pilskog
Morten Jakobsen

VISTA project 6263