The calculation of Ground Heat Exchanger (GHE) performance is very important for predicting the performance and estimating the initial cost of geothermal heat pump systems. In North America it is estimated that on average GHE are oversized by about 10% ~ 30%. A vertical Ground Heat Exchanger (VGHE) is most common because of its smaller environmental influence and land field requirement. This pa...

Abstract: The governing equations of motion for a drill string considering coupling between axial, lateral and torsional vibrations are obtained using a Lagrangian approach. The result leads to a set of non-linear equations with time varying coefficients. A fully coupled model for axial, lateral, and torsional vibrations of drill strings is presented. The bit/formation interactions are assumed ...

This paper describes a simple method to evaluate an acoustic altered zone around the borehole using an array of sonic waveforms. The method is based on a semblance velocity analysis and a nonlinear travel time window is introduced. On the assumption that a velocity gradient of the altered zone may be linear, the nonlinear travel time window is calculated as a function of averaged velocity and a...

In this paper, we present resistivity-logging-measurement simulation with the use of two types of borehole logging devices: those which operate with zero frequency (direct current, DC) and those with higher frequencies (alternate current, AC). We perform simulations of 3D resistivity measurements in deviated wells, with a sharp angle between the borehole and formation layers. We introduce a hie...

A new computer program, FLASH (Flow-Log Analysis of Single Holes), is presented for the analysis of borehole vertical flow logs. The code is based on an analytical solution for steady-state multilayer radial flow to a borehole. The code includes options for (1) discrete fractures and (2) multilayer aquifers. Given vertical flow profiles collected under both ambient and stressed (pumping or inje...

This report describes the activities and preliminary findings of the second year of our project on Storglaciären during the summer of 2002. Ice penetrating radar studies were used together with borehole video and other down-hole experiments to investigate englacial water flow. The radar surveys together with the borehole experiments suggest a new model for englacial drainage, wherein crevasse-l...

The Yucca Mountain Project is conducting a Single Heater Test (SHT) in the Exploratory Studies Facility at Yucca Mountain. This report describes the thermal and thermomechanical data collected for the SHT through the third quarter of heating (through 31 May 1997) and compares the data with numerical predictions in order to gain insight into the coupled Thermal-Mechanical-Hydrologic-Chemical pro...

We present analytical solutions for the temperature around the borehole heat exchanger which account for: (I) finite length line-source; (II) natural vertical gradient of the ground temperature; (III) arbitrary changes of the ground surface temperature. We find that the time-dependent part of the solution decays as a power of the time approaching the steady state limit. The long-time limit and ...

Simulated Thermal Response Test data are analyzed in order to evaluate the effect of the tridimensionality model’s feature in determining the proper value of the soil thermal conductivity and borehole thermal resistance, necessary for the geothermal energy storage systems’ design in real conditions. The 3D system’s simulation during the Thermal Response Test is realized by adopting the finite e...

Knowledge of the ground thermal conductivity is of importance when designing borehole heat exchanger (BHE) systems. As thermal conductivity for any specific rock type varies due to its mineral content, porosity, pore fluid and anisotropy, it is preferable determined in-situ. Choudhary (1976) suggested a method for determining the thermal conductivity which analysed the heat transfer during the ...