The Upper Jurassic Hanifa Formation in central Saudi Arabia consists of burrowed and non-burrowed carbonate strata. This study investigated the impact of bioturbation intensity (expressed here as burrow percentage, BP) and burrow-fills on the elastic velocity of these carbonate strata. Burrowed units of these carbonate strata were classified as UB unit with BP > 15% and LB unit with BP range of 2–15%, whereas the non-burrowed strata were classified as NB unit. Seventy-seven core plugs extracted from these three units were characterized using different laboratory techniques including petrography, petrophysical measurements of porosity, permeability, and velocity, as well as computed tomography scanning to estimate BP. The laboratory analysis results were complemented by rock-physics modeling using the differential effective medium (DEM) theory. The permeability–porosity and velocity–porosity relationships of the combined dataset show noticeable scatter with coefficient of determinations (R²) of 0.03 and 0.11, respectively. Such scatter can be explained largely by variations in BP: samples characterized by BP of > 15% (UB samples) have higher permeability (6–400 mD, where 1 mD = 9.87 × 10^–16 m²) and compressional velocity (> 5000 m/s) at any given porosity compared to LB and NB samples. These observations are explained by the stronger cementation of the host microporous matrix (in UB samples) around burrows as well as the different texture and pore structure in burrow-fills compared to those of the host matrix. Burrows are filled by coarse grains with dominant interparticle, moldic, and vuggy pores, which result in stronger stiffness compared to the weakly cemented microporous matrix in non-burrowed samples. As the BP increases, the fraction of stiff (high elastic moduli) material increases resulting in faster velocity for any given porosity. When BP is incorporated into the regression analysis, the R² for the permeability–porosity and velocity–porosity relationships increased to 0.72 and 0.75, respectively. The experimental velocity–porosity data and the pore type observations were consistent with rock-physics modeling whereby variable equivalent pore aspect ratios (EPARs) were incorporated in the DEM theory. The UB samples, which had relatively higher BP and permeability, were characterized by higher EPARs (> 0.22) compared to LB and NB samples. The outcomes of this study suggest that strata with relatively high BP (i.e., > 15%) and high permeability (i.e., > 6 mD) possess a distinct petroacoustic signature in the velocity–porosity domain, which can be identified using the EPAR-based method. Accordingly, the rock-physics scheme presented here can inform the interpretation of sonic data and the assessment of reservoir quality in burrow-related carbonate hydrocarbon reservoirs and aquifers.

沙特阿拉伯中部的上侏罗统哈尼法组由洞穴和非洞穴碳酸盐岩地层组成。本研究调查了生物扰动强度（此处表示为洞穴百分比，BP）和洞穴填充对这些碳酸盐地层弹性速度的影响。这些碳酸盐岩地层的潜伏地层被归类为 BP > 15% 的 UB 单元和 BP 范围为 2-15% 的 LB 单元，而非潜伏地层被归类为 NB 单元。从这三个单元中提取的 77 个岩心塞使用不同的实验室技术进行了表征，包括岩石学、孔隙度、渗透率和速度的岩石物理测量，以及计算机断层扫描以估计 BP。使用差分有效介质 (DEM) 理论的岩石物理建模补充了实验室分析结果。R ² ) 分别为 0.03 和 0.11。这种散射很大程度上可以通过 BP 的变化来解释：以 BP > 15% 为特征的样品（UB 样品）具有更高的渗透率（6–400 mD，其中 1 mD = 9.87 × 10 ^–16  m ²) 和与 LB 和 NB 样品相比在任何给定孔隙度下的压缩速度 (> 5000 m/s)。这些观察结果可以通过洞穴周围的宿主微孔基质（在 UB 样品中）更强的胶结以及与宿主基质相比洞穴填充物中不同的纹理和孔隙结构来解释。洞穴由具有主要颗粒间、模具和孔洞的粗颗粒填充，与非洞穴样品中的弱胶结微孔基质相比，这导致更强的刚度。随着 BP 的增加，刚性（高弹性模量）材料的比例增加，从而导致任何给定孔隙度的速度更快。当 BP 被纳入回归分析时，R ²渗透率-孔隙度和速度-孔隙度关系分别增加到 0.72 和 0.75。实验速度-孔隙度数据和孔隙类型观察结果与岩石物理模型一致，其中可变等效孔隙纵横比 (EPAR) 被纳入 DEM 理论。与 LB 和 NB 样品相比，具有相对较高 BP 和渗透性的 UB 样品的特征在于较高的 EPAR (> 0.22)。本研究的结果表明，具有相对高 BP（即 > 15%）和高渗透率（即 > 6 mD）的地层在速度-孔隙度域具有明显的岩声特征，这可以使用基于 EPAR 的方法。因此，