Correlating curvature to fault propogation in clay modeled transfer zones

Abstract

Transfer zones are common hydrocarbon traps in extensional tectonic structures. A transfer zone is an area where one fault dies out and its slip is transferred to an adjacent fault. Transfer zones are commonly divided into three categories, convergent, divergent and synthetic, based on the dip of the faults. These zones can be quite subtle and little has been published on their signature in seismic data. Because of the complexity associated with transfer zones and their secondary faults, seismic attributes could prove to be valuable tools. Many of the secondary faults that occur in the proximity of a transfer zone may be below seismic resolution; however, these faults may provide an attribute expression that could aid the interpreter to infer their presence. In this study we compute the curvature of a suite of clay models of transfer zones. We then compare the curvature "attribute" to the underlying faults and fractures seen in the clay model. In this manner we provide a simple analogue model of how curvature, a measure of strain, is correlated to sub-seismic features of interest that can aid in the understanding and interpretation of transfer zone dynamics.

Seismic attribute illumination of a synthetic transfer zone

“…A relay ramp develops between the two en-echelon normal faults. As indicated by Cahoj and Marfurt (2014) in Figure 3b, we expect most positive (K1) and most negative (K2) seismic curvature anomalies in the up thrown and downthrown blocks respectively (Figure 3c). We also expect that anomalous low seismic coherence values will delineate the fault plane (Qi et al 2016), as indicated in Figure 3c.…”

“…Transfer zones also lead to the development of secondary faults, which are generally sub-seismic (Morley et al, 1990). The presence of transfer zones can help interpreters delineate secondary features such as fractures, splay shears and Riedel faults (Cahoj and Marfurt, 2014). Paul and Mitra (2013) prepared a clay model to demonstrate the behavior of synthetic transfer zones; using the surface curvature of this model, Cahoj and Marfurt (2014) illustrated the geometry of these zones.…”

“…The presence of transfer zones can help interpreters delineate secondary features such as fractures, splay shears and Riedel faults (Cahoj and Marfurt, 2014). Paul and Mitra (2013) prepared a clay model to demonstrate the behavior of synthetic transfer zones; using the surface curvature of this model, Cahoj and Marfurt (2014) illustrated the geometry of these zones. In this paper, we discuss intrabasin synthetic transfer zones in the Scotian Shelf near Sable Island with the help of seismic attributes.…”