Importance of rock matrix entry pressure on DNAPL migration in fractured geologic materials
- Univ. of Waterloo, Ontario (Canada)
The capillary pressure versus saturation relationship for various carbonate rocks exhibits a wide range of entry pressures depending on the depositional and diagenetic environment of the rock. The results of a numerical study are presented that focus on the effect of the DNAPL entry pressure of the porous rock matrix on the migration of DNAPL within the fracture network of carbonate rocks. Representative numerical experiments involving the release of DNAPL into a single vertical fracture terminating within a porous carbonate rock that was assigned a variety of measured capillary pressure versus saturation relationships showed that the volume of DNAPL that entered the rock matrix increased dramatically as the entry pressure of the rock matrix decreased. Simulations of a DNAPL-contaminated site located on fractured carbonate bedrock in southern Ontario are also presented which highlight the sensitivity of the extent of the zone of DNAPL contamination within the bedrock to the capillary pressure curves assigned to the rock matrix. One scenario presented demonstrates that the penetration depth and horizontal extent of the zone of DNAPL contamination within the bedrock can be large if the carbonate rock has a high entry pressure, because much of the DNAPL flow is restricted to the fracture network. Another case involving a lower entry pressure for the rock matrix produced a smaller zone of DNAPL contamination, but the bulk of the DNAPL was contained in the rock matrix. The results for both cases suggest that attempts at DNAPL-zone restoration in fractured rock using technologies that are available today would be problematic.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 335334
- Journal Information:
- Ground Water, Journal Name: Ground Water Journal Issue: 2 Vol. 37; ISSN GRWAAP; ISSN 0017-467X
- Country of Publication:
- United States
- Language:
- English
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