Recharge systems for protecting and enhancing groundwate

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TOPIC 1
Recharge systems / Injection well issues, aquifer storage and recovery
building and evaluation of geologic and hydrogeological models representing saturated and unsaturated flow conditions.
Hydrogeologists, hydrochemists, geologists, and water managers can share data and results within the same
environment, which encourages collaboration between disciplines. The workflow can be used to develop and test
solutions to comprehensive water management issues, with unique capabilities to address all aspects of a problem,
from initial characterization and model building to simulation, monitoring, and model calibration and updating.
The workflow tools provided are scalable and therefore can efficiently incorporate as many or as few of the
advanced tools available as required. As a result, the workflow is ideal for both small- and large-scale water management
projects, addressing the most basic to the most complex problems. A wide variety of field data can be combined
with models to verify correlations and validate interpretations.
The workflow allows the integration of the following disciplines:
• geophysical interpretation,
• surface imaging and mapping,
• log interpretation and well correlation,
• complex fault and fracture modeling,
• facies and geophysical modeling,
• hydrodynamic test analysis,
• uncertainty analysis,
• surface and subsurface interaction,
• upscaling processes and property population,
• flow and mass transport simulation.
Advanced tools for aquifer characterization (Schlumberger-Technoguide, 2003) allow the development and exploration
of realistic solution scenarios, reducing uncertainty and risk. Inconsistencies that may be difficult to identify
in two dimensions (2D) are immediately apparent in 3D. By discounting conceptual models that do not fit the available
data, uncertainty in the interpretation is reduced, resulting in a more robust model. The process is then concluded
by the development of a 3D hydrogeological model that represents the conceptual model used to generate a
3D hydrogeological grid (gridding process).
The numerical aquifer simulator ECLIPSE (Schlumberger-Geoquest, 2003) is an integrated part of the workflow
tools, providing a fully implicit, density-dependent, multiphase 3D flow and mass transport solution. The simulator
is based on the proven technology of twenty years of experience as the reservoir simulation software for the oil and
gas industry (Ellis et al., 1996). Aquifer systems can be more fully understood with the simulation of variably saturated
conditions, flow and mass transport modeling, and density-dependent modeling for brine or coastal aquifers.
Processes that may influence the well performance such as clogging and flow dependent skin can be addressed. The
workflow platform allows building and updating of large aquifer models in near real time.
STORING WATER IN UNCONFINED CONDITIONS
A large number of surficial aquifers in the Middle East consist of Alluvial and Eolian sediments. The total thickness
of the sediments varies between 5 and 100 meters. The saturated aquifer is generally less than half of the total thickness
of the sediments. The aquifers are relatively heterogeneous and heavily dominated by paleo-channel systems
generated by surface run-off from large rainfall events through wadi systems during deposition of the alluvial sediments.
Native groundwater quality varies from freshwater to saline.
Storing water in unconfined conditions tends to be more complex compared to storage in confined conditions due
to a number of additional considerations that have to be evaluated when investigating the aquifer. Unconfined
ISMAR 2005 ■ AQUIFER RECHARGE ■ 5th International Symposium ■ 10 –16 June 2005, Berlin