Bioturbated strata in the Upper Cretaceous Aruma Formation, central Saudi Arabia: An analog for aquifers and hydrocarbon reservoirs with large burrows

Abstract

The upper Cretaceous Aruma Formation in Central Saudi Arabia exhibits Thalassinoides-bearing strata resembling a bioturbated carbonate reservoir with large burrows. These burrows possess distinct stratigraphic characteristics. Certain intervals within the formation feature open or partially filled Thalassinoides, creating three-dimensional permeability pathways, while others contain Thalassinoides filled with low-permeability sediments. This comprehensive study investigates the paleoenvironment, ichnological features, bulk permeability influence, and stratigraphic variations of these bioturbated intervals. Incorporating field observations, laboratory analyses (including petrography, geochemical assessments, petrophysical measurements, and computed tomography scanning [CT]), we present the division of the studied interval into three biogenically influenced fluid flow media (BIFM 1–3). BIFM 1 comprises solution-enlarged open Thalassinoides (average shaft diameter: 5 cm) hosted within a mud-dominated matrix. BIFM 2 consists of Thalassinoides with mud-dominated infills (average shaft diameter: 3 cm) embedded in a dolomite matrix. BIFM 3 exhibits compacted open Thalassinoides. These BIFM units demonstrate burrow percentages ranging from 10% to 45%, featuring interconnected networks. The identified units reflect diverse depositional settings, ranging from open marine to restricted lagoon, and distinct stratigraphic positions. By highlighting the sedimentological and stratigraphic controls on the petrophysical properties of carbonate strata containing Thalassinoides with large burrows, this research contributes to the prediction of super-permeability zones in analogous settings.