Well test analysis in fractured media

Karasaki, Kenzi

doi:10.2172/6513751

Cited by 11 publications

(5 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…S s shows a generally decreasing trend with increasing depth, which is reasonable considering the increase in lithostatic pressure with depth, but the spread in values is enormous -15 orders of magnitude. Limitations on the ability of slug tests to provide reliable values of S s have been documented previously (Karasaki, 1987), and the large range of values shown in Figure 5.1 supports this. However, it may still be useful to compare general features of the slug-test S s values with theoretical values based on Equation (5.2), to investigate the interplay of water (C w ) and rock (α) compressibility.…”

supporting

confidence: 62%

Evaluation of uncertainties due to hydrogeological modeling and groundwater flow analysis: Steady flow, transient flow, and thermal studies

Doughty¹,

Karasaki²

2002

View full text Add to dashboard Cite

Starting with regional geographic, geologic, surface and subsurface hydrologic, and geophysical data for the Tono area in Gifu, Japan, we develop an effective continuum model to simulate subsurface flow and transport in a 4 km by 6 km by 3 km thick fractured granite rock mass overlain by sedimentary layers. Individual fractures are not modeled explicitly. Rather, continuum permeability and porosity distributions are assigned stochastically, based on well-test data and fracture density measurements. Lithologic layering and one major fault, the Tsukiyoshi Fault, are assigned deterministically. We conduct three different studies: (1) the so-called base case, in which the model simulates the steady-state groundwater flow through the site, and then stream trace analysis is used to calculate travel times to the model boundary from specified release points; (2) simulations of transient flow during long term pump tests (LTPT) using the base-case model; and (3) thermal studies in which coupled heat flow and fluid flow are modeled, to examine the effects of the geothermal gradient on groundwater flow. The base-case study indicates that the choice of open or closed lateral boundaries has a strong influence on the regional groundwater flow patterns produced by the models, but no field data exist that can be used to determine which boundary conditions are more realistic. The LTPT study cannot be used to distinguish between the alternative boundary conditions, because the pumping rate is too small to produce an analyzable pressure response at the model boundaries. In contrast, the thermal study shows that the temperature distributions produced by the open and closed models differ greatly. Comparison with borehole temperature data may be used to eliminate the closed model from further consideration.

show abstract

supporting

confidence: 62%

Evaluation of uncertainties due to hydrogeological modeling and groundwater flow analysis: Steady flow, transient flow, and thermal studies

Doughty¹,

Karasaki²

2002

View full text Add to dashboard Cite

show abstract

“…The double-porosity model is not well suited for a site like Raymond, in which flow is confined to discrete fractures within a granitic rock matrix that is essentially impermeable. properties, but the late-time transient may be fitted to a Theis curve if the degree of fracture interconnection is large enough relative to area perturbed by the test (Karasaki, 1987). This can occur because at late times fluid is being released from storage at distances far from the well, and flow toward the well is generally radial over the region.…”

Section: Conceptual Considerationsmentioning

confidence: 99%

Hydrogeloogic characterization of fractured rock formations: A guide for groundwater remediators

Cohen¹

1995

View full text Add to dashboard Cite

A field site was developed in the foothills of the Sierra Nevada, California to develop and test a multi-disciplinary approach to the characterization of ground water flow and transport in fractured rocks. Nine boreholes were drilled into the granitic bedrock, and a wide variety of new and traditional subsurface characterization tools were implemented. The hydrogeologic structure and properties of the field site were deduced by integrating results from the various geologic, geophysical, hydrologic, and other investigative methods. The findings of this work are synthesized into this report, which is structured in a guidebook format. The applications of the new and traditional technologies, suggestions on how best to use, integrate, and analyze field data, and comparisons of the shortcoming and benefits of the different methods are presented.

show abstract

“…(9) The finite radius well is partially penetrating (10) In addition to the instantaneous elastic response of aquifer compression and water expansion, gravity drainage of the pores is considered. (11) The drawdown is considered small compared with the saturated thickness so that boundary conditions appropriate for an initially horizontal water table can be imposed. (12) It is also assumed that the vertical flux of water into the aquifer from the unsaturated zone occurs in a manner that varies exponentially with time in response to a step decline in hydraulic head at the water table.…”

Section: Analytical Solutionmentioning

confidence: 99%

“…This type of composite model was used by numerous authors [2,4,6,11,12,14,17,18,[29][30][31][32][33] for the analysis of confined aquifers.…”

Section: Introductionmentioning

confidence: 99%

Effect of wellbore storage and finite thickness skin on flow to a partially penetrating well in a phreatic aquifer

Pasandi

Samani

Barry

2008

Advances in Water Resources

View full text Add to dashboard Cite

Well test analysis in fractured media

Cited by 11 publications

References 33 publications

Evaluation of uncertainties due to hydrogeological modeling and groundwater flow analysis: Steady flow, transient flow, and thermal studies

Evaluation of uncertainties due to hydrogeological modeling and groundwater flow analysis: Steady flow, transient flow, and thermal studies

Hydrogeloogic characterization of fractured rock formations: A guide for groundwater remediators

Effect of wellbore storage and finite thickness skin on flow to a partially penetrating well in a phreatic aquifer

Contact Info

Product

Resources

About