Conceptual Model

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Exploration Technique: Conceptual Model

Exploration Technique Information
Exploration Group: Data and Modeling Techniques
Exploration Sub Group: Modeling Techniques
Parent Exploration Technique: Modeling Techniques
Information Provided by Technique
Lithology: Rock types, rock chemistry, stratigraphic layer organization
Stratigraphic/Structural: Location and shape of permeable and non-permeable structures, faults, fracture patterns
Hydrological: Hydrothermal fluid flow characteristics, up-flow patterns
Thermal: Temperature and pressure extrapolation throughout reservoir, heat source characteristics
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Conceptual Model:
In the broadest terms, a conceptual model is anything used to represent anything else. In geothermal exploration a conceptual model is a descriptive and qualitative model (not used for calculations) integrating and bringing together the physical features of a system to create a representation of the geothermal reservoir.
Other definitions:Wikipedia Reegle


 
Introduction
AIn geothermal exploration a conceptual model is a geologic representation of the subsurface to help visualize the characteristics of the geothermal reservoir. A conceptual model of a geothermal reservoir is an integration of data sets across many disciplines to develop a physical model. Information from field observations, geophysical surveys, geochemical sampling, drilling efforts, and temperature and pressure data are combined to generate an overall picture of the processes and conditions within the reservoir. An ideal conceptual model will show the heat source for the reservoir, the size and shape of the reservoir, the locations of recharges zones, general flow patterns, the main flow channels, permeable and impermeable structures, temperature and pressure conditions, and two-phase and steam dominated zones within the reservoir. [1] Not all conceptual models will incorporate all of the data listed but as more information is learned and added to the model it will become more comprehensive and useful.
 
Use in Geothermal Exploration
A well-constrained conceptual model can help guide decisions when designing an exploration plan and aid in interpreting the results of the collected data. A good conceptual model is very important for selecting locations and targets for drilling.[1] Most conceptual models of geothermal reservoirs are represented as cross sectional views or plane view maps.[2] The cross sectional view is most useful for interpreting how the buoyant flow of geothermal fluids will interact with the permeable formations in the geothermal reservoir. Conceptual models are an important basis for geothermal resource assessment and are ultimately the basis for developing an exploration plan. Conceptual models provide a unified picture of the nature of a geothermal system and play a key role from the beginning of exploration until after development and utilization of a geothermal resource.[1]

Conceptual models come in many forms from very simplified 2D drawing to more complex 3D interpretations.

A simplified sketched model of the krafla geothermal system in northern Iceland.[3]
An example conceptual model of a cross section of a geothermal reservoir showing general flow patterns, temperature contours, and lithology. [2]
A complex 3D model of the Krafla Geothermal system showing faults, eruption fissures, temperatures, flow directions, and a deep low resistivity anomaly interpreted as the magma chamber.[4]




 
Data Access and Acquisition
A conceptual model should integrate data from surface mapping, subsurface data, remote sensing data, geophysical surveys, chemical and isotopic analysis of fluid from surface manifestations and samples from wells, temperature and pressure data, and any other relevant data collected.[1]
 
Best Practices
To develop an effective geothermal conceptual model, it is important to integrate all gathered information (e.g., geochemistry, geophysics, hydrological, structural, and petrological) into a consistent model to answer questions like: Does a reservoir exist? If it exists, how big is it? Is the reservoir sufficiently permeable? What are the controls on permeability? What is the probability of development and expected value? What is the lowest cost drilling strategy to discover, prove, and develop the resource? A fully developed conceptual model will illustrate reservoir fluid and rock properties that affect production performance, such as temperature, permeability, volume, pressure, porosity, and chemistry.[5] Conceptual models should be revised continuously during exploration, development, and utilization to improve and keep the model up to date with the most current information.[1]
 
Potential Pitfalls
When only one conceptual model is developed, there is sometimes a tendency to interpret data to fit that model. Therefore, it is important to develop multiple possible conceptual models that are consistent with all data, so that, as additional data are collected, the model(s) can be adjusted based on the new information. The exploration plan may still target the elements of the most likely model, but probabilities should be estimated for all models to consider the risks being taken for each.








 
References
  1. 1.0 1.1 1.2 1.3 1.4 Gudni Axelsson. 2013. Conceptual Models of Geothermal Systems – Introduction. In: Short Course V on Conceptual Modelling of Geothermal Systems. United Nations University Geothermal Training Programme; 2013/02/24; Santa Tecla, El Salvador. Reykjavik, Iceland: United Nations University; p. N/A
  2. 2.0 2.1 William Cumming. 2009. Geothermal Resource Conceptual Models Using Surface Exploration Data. In: Thirty-Fourth Workshop on Geothermal Reservoir Engineering; 2009/02/09; Stanford, California. Stanford, California: Thirty-Fourth Workshop on Geothermal Reservoir Engineering; p. N/A
  3. Gudmundur S. Bodvarsson,Karsten Pruess. 1983. A Summary of Modeling Studies of the Krafla Geothermal Field, Iceland. Geothermal Resources Council Transactions. 7:391-396.
  4. Mortensen A.K.,Gudmundsson Á.,Steingrímsson B.,Sigmundsson F.,Axelsson G.,Ármannsson H.,Björnsson H.,Ágústsson K.,Saemundsson K.,Ólafsson M.,Karlsdóttir R.,Halldórsdóttir S.,Hauksson T. (Iceland GeoSurvey). 2009. The Krafla Geothermal System. A Review of Geothermal Research and Revision of the Conceptual Model. Reykjavik, Iceland: Iceland GeoSurvey. Report No.: ISOR-2009/057.
  5. William Cumming. 2009. Geothermal resource conceptual models using surface exploration data. In: Thirty-Fourth Workshop on Geothermal Reservoir Engineering; 2009/02/09; Stanford University. Stanford University: Stanford University; p. 6


Page Area Activity Start Date Activity End Date Reference Material
Conceptual Model At Blue Mountain Geothermal Area (Casteel, Et Al., 2010) Blue Mountain Geothermal Area 2010 2010


Conceptual Model At Blue Mountain Geothermal Area (Faulds & Melosh, 2008) Blue Mountain Geothermal Area 2008


Conceptual Model At Coso Geothermal Area (1980) Coso Geothermal Area 1980 1980


Conceptual Model At Coso Geothermal Area (1990) Coso Geothermal Area 1990 1990


Conceptual Model At Coso Geothermal Area (2005) Coso Geothermal Area 2005 2005


Conceptual Model At Coso Geothermal Area (2005-2007) Coso Geothermal Area 2005 2007


Conceptual Model At Coso Geothermal Area (2006) Coso Geothermal Area 2006 2006


Conceptual Model At Dixie Valley Geothermal Area (Bell, Et Al., 1980) Dixie Valley Geothermal Area 1980 1980


Conceptual Model At Dixie Valley Geothermal Area (Benoit, 1999) Dixie Valley Geothermal Area 1976 1976


Conceptual Model At Dixie Valley Geothermal Area (Iovenitti, Et Al., 2012) Dixie Valley Geothermal Area 2012 2012


Conceptual Model At Dixie Valley Geothermal Area (Okaya & Thompson, 1985) Dixie Valley Geothermal Area 1985 1985


Conceptual Model At Dixie Valley Geothermal Area (Parchman, Et Al., 1981) Dixie Valley Geothermal Area 1981 1981


Conceptual Model At Dixie Valley Geothermal Area (Reed, 2007) Dixie Valley Geothermal Area 1998 2004


Conceptual Model At Dixie Valley Geothermal Area (Thompson, Et Al., 1967) Dixie Valley Geothermal Area 1967 1967


Conceptual Model At Dixie Valley Geothermal Area (Waibel, 1987) Dixie Valley Geothermal Area 1987 1987


Conceptual Model At Fenton Hill HDR Geothermal Area (Goff, Et Al., 1988) Fenton Hill HDR Geothermal Area 1988 1988


Conceptual Model At Fenton Hill HDR Geothermal Area (Grigsby & Tester, 1989) Fenton Hill HDR Geothermal Area 1989


Conceptual Model At Long Valley Caldera Geothermal Area (Farrar, Et Al., 2003) Long Valley Caldera Geothermal Area 2003 2003


Conceptual Model At Long Valley Caldera Geothermal Area (Sorey, Et Al., 1991) Long Valley Caldera Geothermal Area 1985 1988


Conceptual Model At North Brawley Geothermal Area (Even, 2012) North Brawley Geothermal Area 2011 2011


Conceptual Model At Raft River Geothermal Area (1976) Raft River Geothermal Area 1976 1976


Conceptual Model At Raft River Geothermal Area (1977) Raft River Geothermal Area 1977 1977


Conceptual Model At Raft River Geothermal Area (1979) Raft River Geothermal Area 1979 1979


Conceptual Model At Raft River Geothermal Area (1980) Raft River Geothermal Area 1980 1980


Conceptual Model At Raft River Geothermal Area (1981) Raft River Geothermal Area 1981 1981


Conceptual Model At Raft River Geothermal Area (1983) Raft River Geothermal Area 1983 1983


Conceptual Model At Raft River Geothermal Area (1987) Raft River Geothermal Area 1987 1987


Conceptual Model At Raft River Geothermal Area (1988) Raft River Geothermal Area 1988 1988


Conceptual Model At Raft River Geothermal Area (1990) Raft River Geothermal Area 1990 1990


Conceptual Model At Raft River Geothermal Area (2011) Raft River Geothermal Area 2011 2011


Conceptual Model At Salt Wells Area (Faulds, Et Al., 2011) Salt Wells Geothermal Area 2011 2011


Conceptual Model At Salton Sea Geothermal Area (1977) Salton Sea Geothermal Area 1977 1977


Conceptual Model At Valles Caldera - Redondo Geothermal Area (Gardner, 2010) Valles Caldera - Redondo Geothermal Area 2010


Conceptual Model At Valles Caldera - Redondo Geothermal Area (Goff, Et Al., 1988) Valles Caldera - Redondo Geothermal Area 1988


Conceptual Model At Valles Caldera - Redondo Geothermal Area (Shevenell, Et Al., 1988) Valles Caldera - Redondo Geothermal Area 1988


Conceptual Model At Valles Caldera - Sulphur Springs Geothermal Area (Gardner, 2010) Valles Caldera - Sulphur Springs Geothermal Area 2010


Conceptual Model At Valles Caldera - Sulphur Springs Geothermal Area (Goff, Et Al., 1988) Valles Caldera - Sulphur Springs Geothermal Area 1988 1988



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