Addressing the acoustic signature of organic-rich mudstones for energy production and sub-surface storage

Albrkawy, Ahmed I., Alves, Tiago M. ORCID: https://orcid.org/0000-0002-2765-3760 and Martins-Ferreira, Marco Antonio Caçador 2026. Addressing the acoustic signature of organic-rich mudstones for energy production and sub-surface storage. Marine Geoscience and Energy Resources , 207951. 10.1016/j.marger.2026.207951

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Abstract

Organic-rich mudstones are commonly identified using borehole geochemical measurements and petrophysical proxies. Yet reproducible log-tied acoustic criteria for their discrimination remain limited. This study compares the acoustic character of organic-rich vs. organic-lean mudstones, and their distinct borehole petrophysical and lithological properties, based on data from four tectonically isolated basins and intervals. The study aims to characterise the acoustic signature of organic-rich mudstones by integrating reflection coefficient (Rc) bandwidth, normalised statistical frequency (fn), density readings, burial depth, total organic content (TOC%), and transformation ratio (TR%) to evaluate how the acoustic behaviour of mudstones reflects variations in organic enrichment, lithological organisation, and burial evolution. Results show that organic-rich mudstone intervals consistently display narrow Rc bandwidth at low fn dominance (<0.005) and positive skewness. This behaviour reflects internal acoustic homogeneity and reduced impedance contrasts. In contrast, lean mudstone intervals exhibit broader Rc distributions at higher fn ranges (>0.005) and negative skewness, indicating greater lithological variability and impedance heterogeneity. The integration in this work defines reproducible Rc-fn diagnostic acoustic fields for mudstone intervals of contrasting organic richness and maturity. Cross-plots against TOC% and basin-modelled TR% confirm the robustness of the acoustic fields and their applicability across basins. This method provides a reproducible alternative geophysical approach for organic-rich mudstone intervals evaluation in complex and poorly investigated systems, offering a transferable framework for distinguishing organic-rich and organic-lean mudstones across contrasting tectono-stratigraphic settings.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences Schools > Physical, Chemical & Environmental Sciences
Publisher:	Elsevier BV
ISSN:	3117-5775
Date of First Compliant Deposit:	10 November 2026
Date of Acceptance:	22 September 2026
Last Modified:	10 Nov 2026 12:45
URI:	https://orca.cardiff.ac.uk/id/eprint/190819

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