• Geothermal Energy

Tracer Interpretation Using Temporal Moments on a Spreadsheet

A method for interpreting geothermal tracer tests is presented. The method is based on the first temporal moment (mean residence time) of the tracer in the subsurface. The individual steps required to interpret a tracer test are reviewed and discussed. An example tracer test directs the user through the interpretation method using the Excel spreadsheet application.

• Tracer Interpretation Using Temporal Moments on a Spreadsheet ( 417kB PDF)
• Tracer Analysis, v. 1.30 ( 1.3MB XLS)
• A Simple, Fast Method of Estimating Fractured Reservoir Geometry from Tracer Tests ( 146kB PDF)

Geocrack

Geocrack2D: A Coupled Fluid Flow/Heat Transfer/Rock Deformation Program for Analysis of Fluid Flow in Jointed Rock The Geocrack2D program was developed at Kansas State University with the objective of providing a tool that can be used in the design and operation of fractured reservoirs It solves the fully coupled fluid flow/heat transfer/rock deformation problem, including discrete fractures. This means that the fracture opening is a function of fluid pressure, nonlinear contact stiffness, and local deformation of the rock due to elastic stresses and thermal contraction. Geocrack2D runs on Sun workstations (Solaris and Sun OS 4.1.3), Windows 95/NT, and Dec Alpha workstations (send email to request this version). Geocrack2D requires an initial mesh. We have developed some generators that create a repeating pattern of rock blocks and joints, a more general generator, GenMesh (Windows 95/NT), and a translator from a completely general finite element mesh generator called Casca

Chemical Models for Optimizing Geothermal Energy Production

UCSD Software

TEQUIL

The TEQUIL (Temperature dependent EQUIL) application package includes chemical models, based on the Pitzer electrolyte equations (1987), which calculate liquid-solid-gas equilibria in complex brine systems by globally minimizing the free energy of a system at constant temperature and pressure. This series of computer programs includes variable temperature (T<250c) models of geothermal brine components at liquid densities, reservoir-brine interactions, scaling and gas breakout as well as mixing, ph, and reinjection compatibilities can be calculated from this package.

GEOFLUIDS

This series of computer programs includes models for calculating PVT properties and vapor/liquid equilibrium from subcritical to supercritical temperatures and pressures. Application of these programs include: the calculation of gas breakout, fluid inclusion studies of reservoir behavior, and the prediction of the solubility of gases. The software implements two models. The default model is an equation of state for the NaCl-H₂O-CO₂-CH₄ system (publication pending) that extends the earlier model for the NaCl-H₂O-CO₂ system reported in Geochimica Cosmochimica Acta (1995), Vol. 59, pages 2869-2882. The second model implements the one fluid corresponding states equation of state model for the H₂O-CO₂-CH₄-N₂ system reported in Geochimica Cosmochimica Acta (2000), Vol. 64, pages 1069-1075. The model is most accurate in the high temperature and pressure ranges from about 1.3 times the critical temperature of the least volatile component to 2000 K and from 0 to 100 kbar.

GEOHEAT

This series of programs will calculate the heat content of geothermal brines and their vapor phases. It will allow the rapid calculation of liquid/vapor ratios, available heat, etc. It addresses enthalpy of natural fluids in the NaCl-H₂O and H₂O-CO₂-CH₄ systems.

Software for Analyzing Geothermal Direct Use Systems Economics

Geo-Heat Center Software

For further details and how to access to this software, please contact Tonya (Toni) Boyd at the Geo-Heat Center, Oregon Institute of Technology.

DHE - Downhole Heat Exchanger program written in Quick Basic language, calculates the heat output (kW) from a downhole heat exchanger in a well where convective steady-state heat transfer is predominant.

QPIPE - a program written in Quick Basic language, calculates the heat loss from buried piping for both insulated and uninsulated lines.

HEATOOLS - is a spreadsheet which provides calculations of heat transfer form bare pipe to air, Reynolds numbers and film coefficients for the bare-pipe-to-air situation, and heat loss from ponds.

BAREPIPE - is a spreadsheet that evaluates the feasibility of using uninsulated buried piping in geothermal systems.

GHS - is a spreadsheet that is a tool for evaluating the economics of various types of heating systems for greenhouses.

TRNSLINE - is an economics spreadsheet which allows the user to determine the preliminary economics for transporting geothermal fluids over moderate distances (thousands of feet).

HEETX - is a spreadsheet that permits the user to alter inlet conditions (temperature, flow, etc.) and determine new heat exchanger capacity (Btu/hr) and outlet temperatures. It is frequently necessary to determine the performance of a particular heat exchanger under conditions other than those for which the heat exchanger was designed.

COST - Includes calculations related to the economics of using geothermal compared to natural gas for a user defined heating load. This is a tool that is best used to evaluate the feasibility of using geothermal to supply an industrial process or a large space heating load.