From Fault Likelihood to Fault Networks: Stochastic Seismic Interpretation Through a Marked Point Process with Interactions

Abstract

Faults are crucial subsurface features that significantly influence the mechanical behavior and hydraulic properties of rock masses. Interpreting them from seismic data may lead to various scenarios due to uncertainties arising from limited seismic bandwidth, possible imaging errors, and human interpretation noise. Although methods addressing fault uncertainty exist, only a few of them can produce curved and sub-seismic faults simultaneously while quantitatively honoring seismic images and avoiding anchoring to a reference interpretation. This work uses a mathematical framework of marked point processes to approximate fault networks in two dimensions with a set of line segments. The proposed stochastic model, namely the Candy model, incorporates simple pairwise and nearby connections to capture the interactions between fault segments. The novelty of this approach lies in conditioning the stochastic model using input images of fault probabilities generated by a convolutional neural network. The Metropolis–Hastings algorithm is used to generate various scenarios of fault network configurations, thereby exploring the model space associated with the Candy model and reflecting the uncertainty. Probability level sets constructed from these fault segment configurations provide insights on the obtained realizations and on the model parameters. The empty space function produces a ranking of the generated fault networks against an existing interpretation by testing and quantifying their spatial variability. The approach is applied to two-dimensional sections of seismic data, in the Central North Sea.