Anisotropy in large parts of the earth's crust, particularly in sedimentary basins is well modeled by orthorhombic (ORT) symmetry. Schoenberg and Helbig (1997) introduced the orthorhombic medium as a combination of vertical fractures and horizontal fine layering, which resembles quite much of a petroleum reservoir. Hence understanding the behavior of the seismic response for this particular medium has become quite popular for this past years.
A well data is provided in this study for observing the seismic signature of a fractured reservoir, which known as ORT medium. The kinematic parameters derived by Stovas (2016) are utilized in this study. Polar plot of azimuthal dependence of these kinematic parameters is conducted in order to observe the difference signature of a fractured and non-fractured medium. Furthermore, the effect of considering overburden above the fractured reservoir is also discussed.
Since well data and seismic wavelength work in a slightly different frequency domain, a process that helps to transfer a series of a thin layered model that match with seismic wavelength is required. Upscaling is commonly known to handle this issue. Two methods of upscaling, which are classic or famously known as Backus average and least square, are conducted, and the results are compared. In addition to that, in a fractured reservoir observation, two approaches to introducing fractures are also discussed and compared. These approaches are to introduce the fractures before and after the upscaling process.
This study aims to observe the seismic signature in the form of kinematic parameters that are azimuthally dependent for a fractured reservoir with the condition, as stated before.