Rock mechanical properties of immature, organic-rich source rocks and their relationships to rock composition and lithofacies

Israa Salem Abu Mahfouz, Regina Iakusheva, Thomas Finkbeiner, Joe Cartwright, Volker Vahrenkamp

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Mechanical properties of layered rocks are critical in ensuring wellbore integrity and predicting natural fracture occurrence for successful reservoir development, particularly in unconventional reservoirs for which fractures provide the main pathway for hydrocarbon flow. We examine rock mechanical properties of exceptionally organic-rich, immature source rocks from Jordan and understand their relationships with rock mineral composition and lithofacies variations. Four depositional microfacies were identified: organic-rich mudstone, organic-rich wackestone, silica-rich packstone, and fine-grained organic-rich wackestone. The four types exhibit various mineralogical compositions, dominated by carbonates, biogenic quartz, and apatite. Leeb hardness ranges between 288 – 654, with the highest average values in silica-rich packstone and organic-rich mudstone. The highest uniaxial compressive strength (derived from the intrinsic specific energy measured by Epslog's Wombat scratch device), compressional, and shear waves velocities were measured in organic-rich mudstones (140 MPa, 3368 m/s, and 1702 m/s, respectively). Porosity shows higher average values in organic-rich wackestones and fine-grained organic-rich wackestones (33% – 35%). Silica-rich packstone and organic-rich mudstone have brittle properties, while organic-rich wackestone and fine-grained organic-rich wackestone are ductile. High silica contents are correlated positively with brittleness. A strong hardness-brittleness correlation suggests that Leeb hardness is a useful proxy for brittleness. Our study allows a better understanding of the relationships between lithofacies, organic content and rock mechanical properties, with implications for fracking design to well completion and hydrocarbon production. Further work involving systematic sampling and a more rigorous study is still required to better understand the spatial distribution of target lithologies and their mechanical properties.
Original languageEnglish (US)
JournalPetroleum Geoscience
StatePublished - Jan 12 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-02-13
Acknowledgements: This research was funded by King Abdullah University of Science and Technology (KAUST), faculty baseline funding. The authors extend their gratitude to the Ministry of Energy and Mineral Resources of Jordan (MEMR) for providing the core samples used in this study from the cored wells drilled by Royal Dutch Shell through the unique immature carbonate source rocks of Jordan. The authors also thank King Abdullah University of Science and Technology (KAUST) for the financial support. We are grateful to the editor and reviewers (John Powell and the anonymous reviewer) for the positive feedback and insightful and helpful comments.

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Economic Geology
  • Geochemistry and Petrology
  • Geology
  • Fuel Technology


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