The puzzling influence of Ophiomorpha (trace fossil) on reservoir porosity: X-ray microtomography analysis
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AuthorMíguez Salas, Olmo; Cabrera Ortiz, José; Dorador Rodríguez, Javier; Rodríguez Tovar, Francisco J.
BioturbationPetrophysical propertiesMicro-CTReservoir qualityDiagenesis
Miguez-Salas O... [et al.]. (2022), The puzzling influence of Ophiomorpha (trace fossil) on reservoir porosity: X-ray microtomography analysis. Front. Earth Sci. 10:1010729. doi: [10.3389/feart.2022.1010729]
SponsorshipMCIN/AEI PID 2019-104625RB100; FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento/Projects P18RT-4074 B-RNM-072-UGR18 A-RNM-368-UGR20 PPJIA2021-07; Junta de Andalucia RNM-178; Universidad de Granada UCE-2016-05 University of Granada; Humboldt Postdoctoral Fellowship; Ministry of Science and Innovation, Spain (MICINN) IJC 2019038866-I
Bioturbation can influence petrophysical properties (e.g., porosity, permeability) of sedimentary rocks and, in consequence, reservoir quality. The impact can be positive, negative, or neutral, requiring detailed ichnological analysis. Ophiomorpha, a branched cylindrical burrow with diagnostic peloidal wall, may be present in bioturbated reservoirs that exhibit properties of both superpermeability and reduced porosity/permeability. However, no mechanistic understanding of how Ophiomorpha positively or negatively impacts petrophysical properties has yet been established. This study presents highresolution X-ray microtomographic analysis of how the features of Ophiomorpha (i.e., peloidal wall vs. burrow fill) influence porosity distribution in deep-water deposits (Neogene Tabernas Basin, SE Spain). The results show that the peloidal burrow wall exhibits the lowest porosity (up to six orders of magnitude lower than burrow fill or host sediment), while surrounding sediment shows variable values. Abrupt porosity changes within the fill material likely relate to burrow-associated diagenesis. A refined understanding of the features of Ophiomorpha and their associated porosity distribution help to constrain understanding of their diverse impacts on reservoir properties.