Characterization and quantification of pneumatic fracturing effects at a clay till site

Environ Sci Technol. 2008 Jan 15;42(2):570-6. doi: 10.1021/es071294s.

Abstract

Environmental fracturing offers assistance to remediation efforts at contaminated, low-permeability sites via creation of active fracture networks, and hence, reduction of mass transport limitations set by diffusion in low-permeability matrices. A pilot study of pneumatic fracturing, focusing on direct documentation of fracture propagation patterns and spacing, was performed at a typical basal clay till site. The study applied a novel package of documentation methods, including injection of five tracers with different characteristics (bromide, uvitex, fluorescein, rhodamine WT, and brilliant blue), subsequent tracer-filled fracture documentation via direct and indirect methods, and geological characterization of the fractured site. The direct documentation methods consisted of Geoprobe coring, augering, and excavation. A mass balance and conceptual model have been established for the distribution of the injected tracers in the subsurface. They reveal that tracer was distributed within 2 m of the fracturing well, mainly in existing fractures above the redox boundary (2 to 4 m.b.s.; 5 to 10 cm spacing). Spacing of observed tracer-filled fractures was large (>1 m) at greater depths. The number of fractures induced/activated could possibly be increased via adjustments to the fracturing equipment design.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Silicates*
  • Clay
  • Geological Phenomena
  • Geology
  • Water Movements
  • Water Pollutants
  • Water Supply*

Substances

  • Aluminum Silicates
  • Water Pollutants
  • Clay