On the scale dependence of estimating burrow intensity of Thalassinoides from two-dimensional views

Abstract

Many previous studies have documented carbonate hydrocarbon reservoirs and aquifers with Thalassinoides. Although the linkages among burrow intensity, burrow connectivity, and reservoir quality in these reservoirs have been evaluated recently, how burrow intensity of a complex network of Thalassinoides is reflected on their two-dimensional (2D) views is less constrained. Yet, such quantification is essential to understanding the characteristics of these reservoirs. This study integrates geostatistical modeling and lacunarity analysis to understand how the representative elementary area (REA) of Thalassinoides in 2D views varies with burrow intensity and size. Lacunarity data suggested that the spatial patterns of Thalassinoides in 2D views are independent of burrow intensity but strongly depend on burrow size and can be present as 1) clustered objects or 2) a random pattern of masses. The REAs of Thalassinoides can be defined only when the burrows are represented as a random pattern of masses because only then do they show statistical invariance with increasing size of 2D views. Accordingly, this study defines a proxy that can be used as the initial screening method to determine whether a 2D view shows Thalassinoides as clustered objects or a random pattern of masses. Such a proxy eventually determines whether the 2D view can be used to estimate the intensity of the Thalassinoides. This workflow can also be tested for other types of burrows.