We investigated the influence of sample size on laboratory compressional-wave velocity ( \(\:{V}_{p}\) ) in bioturbated carbonates from the upper Ulayyah Member of the Hanifa Formation. A total of thirty core plugs, ranging from 1.5 to 6 inches, were extracted from five boulders. These samples were analyzed using medical CT imaging, characterized through dyed thin sections, and assessed for porosity (both helium and bulk density) as well as \(\:{V}_{p}\) using the Proseq® ultrasonic system. The samples were categorized into two styles: Burrow Network (BN) and Bioretexturing (BR). The bulk porosity for both styles was found to be comparable, with a median of approximately 15.9%, after the exclusion of two probable cemented outliers. However, the behavior of \(\:{V}_{p}\) varied between the two styles: the mean \(\:{V}_{p}\) for BN was approximately 4,931 m/s (with a standard deviation of 158 m/s), which exhibited an increase with core diameter (log fit R²≈0.67), converging around 3 to 4 inches. In contrast, the mean \(\:{V}_{p}\) for BR was approximately 4,630 m/s (with a standard deviation of 228 m/s), demonstrating a weak dependence on size (R²≈0.05) and a stronger influence of porosity (R² reaching up to 0.87 when outliers were excluded). We conclude that the representative elementary volume for acoustic measurements is contingent upon bioturbation: in our dataset, BN samples demonstrate convergence towards a stable ultrasonic Vp at around 3–4 inches; considering the restricted replication with large cores, we suggest this as initial guidance pending further data.
