A framework for quantifying size dependent deformation of nano-scale pores in mudrocks

Simon Emmanuel*, Ruarri J. Day-Stirrat

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The evolution of pore size distributions during sediment consolidation controls critical parameters such as porosity and permeability. Two phenomenological models are developed that describe the evolution of pore size distributions during stress induced consolidation. The first model predicts the evolution of pores subjected to an applied stress for systems in which all pores deform equally irrespective of size; in the second model, the rate of pore deformation decreases with size (i.e., smaller pores deform less readily than larger ones). To determine which model best describes the behavior of clay-rich rocks during consolidation, cumulative void volume curves from consolidation experiments carried out on Boston Blue Clay are compared with results from numerical simulations. While the uniform deformation model is able produce a good fit during the initial stage of the consolidation (0.1-1. MPa), it is unable to capture system behavior at elevated stresses (1-10. MPa). By contrast, the size dependent deformation model produces excellent fits with the data at both initial and later stages of consolidation. Furthermore, the model shows that size dependent behavior is restricted to pores with radii of <. 100. nm; significantly, small pores may be up to 47% less compressible than large pores. Crucially, by comparing sediments from different burial depths but possessing similar mineralogical compositions, the framework can be used to assess the behavior of natural sediments under geological conditions.

Original languageAmerican English
Pages (from-to)29-35
Number of pages7
JournalJournal of Applied Geophysics
Volume86
DOIs
StatePublished - Nov 2012

Bibliographical note

Funding Information:
SE thanks the Israeli Science Foundation for their generous support. RJDS received support from UT Geofluids . Peter Flemings, Julia Schneider, Yao You (University of Texas), John “Jack” Germaine (Massachusetts Institute of Technology) are thanked for useful discussions.

Keywords

  • Clays
  • Compliance
  • Consolidation
  • Diagenesis
  • Numerical modelling
  • Pore size distribution

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