Fractional flow dimensions and hydraulic properties of a fracture-zone aquifer, Leppävirta, Finland

1998 ◽  
Vol 6 (3) ◽  
pp. 327-340 ◽  
Author(s):  
J. Leveinen ◽  
E. Rönkä ◽  
J. Tikkanen ◽  
E. Karro
Keyword(s):  
Fracture Zone ◽  
Hydraulic Properties ◽  
Fractional Flow ◽  
Flow Dimensions

scholarly journals Scale dependency of fractional flow dimension in a fractured formation

2011 ◽  
Vol 15 (7) ◽  
pp. 2165-2178 ◽  
Author(s):  
Y.-C. Chang ◽  
H.-D. Yeh ◽  
K.-F. Liang ◽  
M.-C. T. Kuo
Keyword(s):  
Field Data ◽  
Geothermal Field ◽  
Fractured Media ◽  
Fractional Flow ◽  
Hydraulic Test ◽  
Flow Paths ◽  
Flow Dimension ◽  
Flow Geometry ◽  
Flow Dimensions ◽  
Observation Wells

Abstract. The flow dimensions of fractured media were usually predefined before the determination of the hydraulic parameters from the analysis of field data in the past. However, it would be improper to make assumption about the flow geometry of fractured media before site characterization because the hydraulic structures and flow paths are complex in the fractured media. An appropriate way to investigate the hydrodynamic behavior of a fracture system is to determine the flow dimension and aquifer parameters simultaneously. The objective of this study is to analyze a set of field data obtained from four observation wells during an 11-day hydraulic test at Chingshui geothermal field (CGF) in Taiwan in determining the hydrogeologic properties of the fractured formation. Based on the generalized radial flow (GRF) model and the optimization scheme, simulated annealing, an approach is therefore developed for the data analyses. The GRF model allows the flow dimension to be integer or fractional. We found that the fractional flow dimension of CGF increases near linearly with the distance between the pumping well and observation well, i.e. the flow dimension of CGF exhibits scale-dependent phenomenon. This study provides insights into interpretation of fracture flow at CGF and gives a reference for characterizing the hydrogeologic properties of fractured media.

Interpretation of single-well tracer tests using fractional-flow dimensions. Part 2: A case study

2002 ◽  
Vol 10 (3) ◽  
pp. 357-367 ◽  
Author(s):  
Kornelius Riemann ◽  
Gerrit van Tonder ◽  
Panganai Dzanga
Keyword(s):  
Tracer Tests ◽  
Fractional Flow ◽  
Single Well ◽  
Flow Dimensions

Fractional Flow Reserve: Does a Cut-off Value add Value?

2016 ◽  
Vol 11 (1) ◽  
pp. 17
Author(s):  
Shah R Mohdnazri ◽  
◽  
◽  
◽  
Thomas R Keeble ◽  
...  
Keyword(s):  
Fractional Flow Reserve ◽  
Coronary Intervention ◽  
Grey Zone ◽  
Fractional Flow ◽  
Non Invasive ◽  
Invasive Test ◽  
Flow Reserve ◽  
A Value ◽  
Percutaneous Coronary ◽  
Value Add

Fractional flow reserve (FFR) has been shown to improve outcomes when used to guide percutaneous coronary intervention (PCI). There have been two proposed cut-off points for FFR. The first was derived by comparing FFR against a series of non-invasive tests, with a value of ≤0.75 shown to predict a positive ischaemia test. It was then shown in the DEFER study that a vessel FFR value of ≥0.75 was associated with safe deferral of PCI. During the validation phase, a ‘grey zone’ for FFR values of between 0.76 and 0.80 was demonstrated, where a positive non-invasive test may still occur, but sensitivity and specificity were sub-optimal. Clinical judgement was therefore advised for values in this range. The FAME studies then moved the FFR cut-off point to ≤0.80, with a view to predicting outcomes. The ≤0.80 cut-off point has been adopted into clinical practice guidelines, whereas the lower value of ≤0.75 is no longer widely used. Here, the authors discuss the data underpinning these cut-off values and the practical implications for their use when using FFR guidance in PCI.

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