A new statistical dispersion model for tracer tests and contaminant spread in porous media
- Univ. of Tulsa, OK (United States)
Dispersion of solutes moving in permeable media is an essential control to describe fluid flow in permeable media. Dispersion can be thought of as a spreading of a solute caused by the presence of microscopic inhomogeneities. An accurate model for dispersion is needed for accurate estimation of oil recovery efficiencies and clean up costs of subsurface contaminants. Current approaches utilizing the fickian assumption fall short in describing the real physics of spreading during a solute transport process. Numerous field investigations have shown that dispersivities measured in the field are much larger than those measured in the lab for the same type of porous material. Moreover, field measured dispersivities have been shown to be scale dependent, that is, a tracer test conducted over a longer travel path will yield a larger dispersivity value than a tracer test conducted in the same geologic formation over a shorter travel path. Numerous approaches to address this problem have been developed yet none attempted to go beyond the Fickian dispersion assumption. In this study, a convective dispersivity is introduced. New model assumes that dispersion is dimensionless and mainly determined by pore size distribution. The new model results in a spread that increases linearly with time contrary to conventional model, which predicts a mixing zone length that increases with square root of time. Therefore, new model explains the field test results that indicate increasing dispersivity with distance. The model validations are in perfect agreement with experimental results, which include; Ganapathy et al.`s slug experiment on Antolini sandstone, Handy`s radioactive tracer experiment on Alhambra sandstone, and CT experiment conducted at BDM-OK/NIPER facilities on Tallant sandstone.
- Research Organization:
- US Department of Energy (USDOE), Washington DC (United States); Amoco Production Co., Houston, TX (United States); Conoco, Inc., Stamford, CT (United States)
- OSTI ID:
- 377206
- Report Number(s):
- CONF-9509296-; ON: DE96001221; TRN: 96:004054-0041
- Resource Relation:
- Conference: 2. international petroleum environmental conference: environmental issues and solutions in petroleum exploration, production, and refining, New Orleans, LA (United States), 25-27 Sep 1995; Other Information: PBD: 1995; Related Information: Is Part Of Environmental issues and solutions in petroleum exploration, production and refining; Sublette, K.L. [ed.]; PB: 1078 p.
- Country of Publication:
- United States
- Language:
- English
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