Using SWIW Tests to Understand Fracture Effects
Source: Dan Hawkes
Modeling of flow and transport in fractured rock remains a challenging problem in hydrogeology, one that particularly arises in the context of finding and developing appropriate sites for radioactive waste containment. The single-well injection-withdrawal (SWIW) tracer test is a method used to estimate the tracer retardation properties of fractured rock or fracture zones. ESD’s Chris Doughty recently joined a team of scientists (including ESD’s Chin-Fu Tsang) in studying, via numerical modeling, the effects of single-fracture aperture heterogeneity on SWIW-test tracer breakthrough curves. They demonstrated that the fracture area that meets the flowing water, the specific flow-wetted surface of the fracture, can be determined by matching the observed breakthrough curve for a heterogeneous fracture to that for a homogeneous fracture with an equivalent property parameter. Their results point to the possibility of distinguishing the effect of the regional pressure gradient from that of diffusion through the use of multiple tracers with different P m values.
For more information, go to: http://link.springer.com/content/pdf/10.1007%2Fs10040-013-0988-x.pdf
Citation: Larsson, M., C. Doughty, C.-F. Tsang, and A. Niemi (2013), Understanding the effect of single fracture heterogeneity from single well injection withdrawal (SWIW) tests. Hydrogeology Journal, DOI 10.1007/s10040-013-0988-x.
Funding Source: Sweden, Japan, DOE