Volumetric impact of fault perturbation in the first Fresnel zone

Abstract

Resolution within seismic imaging must be understood in all three dimensions to make quantitative approximations of subsurface geometries. Constructive interference of incident spherical waves within the first Fresnel zone will limit the resolution due to spatial aliasing. Motivated by the problem of estimating the influence of this effect on the volume uncertainty several interpretations of trapping faults, being equally probable within the first Fresnel zone, are perturbed and multiple realizations of a structural model constructed. After estimating the depth dependent mean frequency and velocity within a zone around the fault plane, the fault interpretations are stochastically perturbed. The frequency- and velocity-dependent perturbations of the dips are analytically derived based on geometric considerations. The anticipated maxima of the repositioned fault dips specify thresholds for deterministic definitions of high and low cases for the fault geometries in a framework. The structural models, resulting from repositioning the faults, show significant alterations of the hanging-wall and footwall horizon terminations due to the varying dips and repositioning of the interpretation. We have applied our to the structural and stratigraphic interpretation obtained for a prospect in the Gulf of Mexico. The spatial variations of the bounding faults result in a spread of volumetric outcomes when analyzing the gross rock volume of the compartment.

3-D Structural geological models: Concepts, methods, and uncertainties

“…Uncertainties in seismic data have been analyzed in numerous studies (e.g. Thore et al, 2002;Glinsky et al, 2005;Suzuki et al, 2008;Weinzierl et al, 2016) and can mainly be assigned to processing steps (stacking, migration, time-depth-conversion) and the subsequent interpretation step.…”

Structural Interpretation of Sparse Fault Data Using Graph Theory and Geological Rules

“…Observation gaps between 2D seismic lines, outcrops, boreholes or focal mechanisms are common. Even when 3D seismic data is available, image quality can be poor near faults [Botter et al, 2014, Iacopini et al, 2016, Weinzierl et al, 2016, Botter et al, 2017. As a result, defining a structural architecture is often tedious and prone to uncertainty.…”

A parametric fault displacement model to introduce kinematic control into modeling faults from sparse data

“…We propose using data located not only on the fault surface but also in the volume surrounding the fault (near-fault (a) (b) Figure 2: The seismic reflectors are blurred close the fault surface. Determining the intersections between fault and horizons in the hanging wall and in the footwall is not straightforward (Weinzierl et al, 2016) and slip measurements on the fault surface are usually highly uncertain. observations) to better constrain displacement on the fault surface.…”

“…However, the distributed damage associated with faulting perturbs the seismic imaging of faults (Sibson, 1977;Botter et al, 2014;Iacopini et al, 2016;Weinzierl et al, 2016;Botter et al, 2017) and the nearfault geometry is generally poorly constrained. This leads to uncertainties in oil and gas flow simulations and volume assessments (Hollund et al, 2002;Thore et al, 2002;Rivenaes et al, 2005;Richards et al, 2015).…”