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Many of the world’s productive Jurassic reservoirs are intensively bioturbated, including the sediments of the Upper Jurassic Hanifa Formation. Hydrocarbon exploration and production from such reservoirs require a reliable prediction of petrophysical properties (i.e., porosity, permeability, acoustic velocity) by linking and assessment of ichnofabrics and trace fossils and determining their impact on reservoir quality. In this study, we utilized outcrop carbonate samples from the Hanifa Formation to understand the main controlling factors on reservoir quality (porosity and permeability) and acoustic velocity of bioturbated carbonates, by using thin-section petrography, SEM, XRD, CT scan, porosity, permeability, and acoustic velocity measurement. The studied samples are dominated by Thalassinoides burrows that have burrow intensity ranging from ~4% to 27%, with porosity and permeability values ranging from ~1% to 20%, and from 0.002 mD up to 1.9 mD, respectively. Samples with coarse grain-filled burrows have higher porosity (average µ = 14.44% ± 3.25%) and permeability (µ = 0.56 mD ± 0.55) than samples with fine grain-filled burrows (µ = 6.56% ± 3.96%, and 0.07 mD ± 0.16 mD). The acoustic velocity is controlled by an interplay of porosity, bioturbation, and mineralogy. Samples with relatively high porosity and permeability values (>10% and >0.1 mD) have lower velocities (<5 km/s) compared to tight samples with low porosities and permeabilities (<10% and <0.1 mD). The mineralogy of the analyzed samples is dominated by calcite (~94% of total samples) with some quartz content (~6% of total samples). Samples characterized with higher quartz (>10% quartz content) show lower velocities compared to the samples with lower quartz content. Bioturbation intensity, alone, has no control on velocity, but when combined with burrow fill, it can be easier to discriminate between high and low velocity samples. Fine grain-filled burrows have generally lower porosity and higher velocities (µ = 5.46 km/s) compared to coarse grain-filled burrows (µ = 4.52 km/s). Understanding the main controlling factor on petrophysical properties and acoustic velocity of bioturbated strata can enhance our competency in reservoir quality prediction and modeling for these bioturbated units.

&lt;p&gt;The Miocene Dam Formation in the Al-Lidam area of Eastern Saudi Arabia consists of a succession&amp;#160;&lt;/p&gt;&lt;p&gt;of mixed siliciclastic-carbonate sequences that were deposited during Miocene (Burdigalian)&amp;#160;&lt;/p&gt;&lt;p&gt;times. Stratigraphic equivalents of the Dam Formation occur as hydrocarbon reservoir intervals in&amp;#160;&lt;/p&gt;&lt;p&gt;the Arabian Plate. Reservoir quality of carbonate rocks is controlled by a combination of&amp;#160;&lt;/p&gt;&lt;p&gt;depositional setting and post-depositional diagenetic factors.&amp;#160;&lt;/p&gt;&lt;p&gt;In this study, fifteen lithofacies were identified as they were deposited on a low angle dipping&amp;#160;&lt;/p&gt;&lt;p&gt;carbonate ramp, under supratidal, beach, intertidal and shallow subtidal conditions. Carbonate&amp;#160;&lt;/p&gt;&lt;p&gt;diagenesis has been examined using: thin-section petrography, SEM, XRD and&amp;#160;&lt;/p&gt;&lt;p&gt;cathodoluminescence. These analytical tools have shown that the intertidal lithofacies are&amp;#160;&lt;/p&gt;&lt;p&gt;influenced by extensive meteoric dissolution and minor cementation. Marine diagenesis was&amp;#160;&lt;/p&gt;&lt;p&gt;restricted to beach grainstone and subtidal lithofacies, in the form of aragonite and high magnesium&amp;#160;&lt;/p&gt;&lt;p&gt;calcite cement. Shallow burial conditions were inferred by grain contacts represented by point,&amp;#160;&lt;/p&gt;&lt;p&gt;suture and concavo-convex contacts. Mimetic dolomitization for the whole succession was also&amp;#160;&lt;/p&gt;&lt;p&gt;observed. Three fourth - order, shallowing upward sequences were identified in the study area, and&amp;#160;&lt;/p&gt;&lt;p&gt;they are separated by two sequence boundaries. A clear relation between sequence surfaces and&amp;#160;&lt;/p&gt;&lt;p&gt;diagenetic processes was observed; meteoric diagenesis and dolomitization increases upwards in&amp;#160;&lt;/p&gt;&lt;p&gt;each sequence. Porosity and permeability measurements have shown that the highest values are&amp;#160;&lt;/p&gt;&lt;p&gt;associated with the HST of each sequence, followed by the TST and the LST. The results of this&amp;#160;&lt;/p&gt;&lt;p&gt;study can help in understanding of diagenetic processes, and consequently in developing better&amp;#160;&lt;/p&gt;&lt;p&gt;and more accurate predictions of the porosity and permeability distribution within hydrocarbon&amp;#160;&lt;/p&gt;&lt;p&gt;reservoirs.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;