This work is concerned with the nonreactive transport of solute materials in groundwater, or hydro‐dispersive transfer. Several types of flow fields are considered: linear (or uniform) flow with one‐ and two‐dimensional dispersion and radial flow under diverging and converging conditions. The analysis includes the two main possibilities for introduction of solutes into an aquifer: continuous and instantaneous (or slug) injection. Different solutions from the literature plus some original solutions for dispersion in a linear flow field have been unified by transposing the solutions into dimensionless variables of concentration (CR), time (tR), and the Peclet number (P). This permits an analysis of the errors committed in some commonly used approximations for dispersion as a function of P. In the case of radial flow, a numerical method using finite differences has been developed that can be applied to either diverging or converging flow problems. Results in dimensionless form when compared to the only analytical approximations that could be found (for continuous injection in a diverging flow field) indicate that the approximate solutions are in error when P ≤ 10. The radial flow results are also compared to those for linear flow fields to demonstrate that in most cases either approach can be used as long as P > 3. A series of dimensionless type curves has been developed showing CR versus tR for practical ranges of P. A simple method of interpreting tracer tests is proposed using these type curves. One is able to directly determine dispersivity and kinematic porosity using curve matching techniques. Results from some recent field tests in France are analyzed using this approach. There is definite confirmation from these investigations that the apparent (macroscopic) dispersivity can vary depending on the distances used in the field.

A mathematical model is presented for investigating the non‐steady state temperature behavior of a pumped aquifer during reinjection of a fluid at a temperature different from that of the native water. Results are presented in terms of dimensionless parameters and should be helpful in the design of geothermal space‐heating projects. Applications to practical cases are also included.

This paper presents the results of a theoretical study on the thermal behavior of a hot water storage system in an aquifer using a single well. It is shown that the storage efficiency and temperature are controlled by a limited number of dimensionless groups that depend on the aquifer's physical characteristics and the storage operating parameters. A numerical model is checked against analytical solutions and is then used to evaluate the variation with time of the well temperature during production periods for symmetrical cycles (production volume and flowrate equal to injection volume and flowrate). From these results, type curves are plotted for several sets of dimensionless parameters, covering the range of practical applications. Effects of unequal injection and production periods, standby periods, and other operating conditions are also investigated. Practical recommendations are made for efficient storage projects. INTRODUCTIONThe depletion of classical resources in fossil fuels combined with high inflation rates has recently enhanced interest in developing the exploitation of alternate energy sources and in improving efficiency in the use of energy in general. Along these lines, hot water storage in permeable geological layers appears particularly attractive, for it provides a way of transferring energy from a period of low consumption where it is being produced, into peak hours or seasons.The most important parameters in a heat storage project are (1) the recovery factor (i.e., the ratio of the quantity of energy recovered to that injected) which determines the project economic feasibility and (2) the energy (or temperature) level in the recovered water and its variation during production, which conditions the type of surface utilization. These parameters depend upon the storage physical characteristics (aquifer reservoir thickness, thermal conductivity, heat capacity, etc.) and operating conditions (production and injection rates, duration of injection and production cycles, etc.).In order to facilitate rapid technical evaluations of heat storage projects, and to assess their economic feasibility without engaging into heavy investments, a general study was undertaken of the various parameters that would influence the behavior of such systems. The study, restricted to the case where the same borehole is used for hot water injection and production, included both a theoretical investigation and a field experiment. The theoretical results, which were used to construct type curves convenient for practical applications, are presented hereinafter. Results and analysis of the field experiment are the subject of a companion paper. ScoPE OF STUDYThe theoretical study is concerned with storage of hot water under liquid phase (sensible energy storage) in relatively deep aqufers. Compared with that in shallow aquifers,• Now with Flopetrol, 245 deep aquifer storage appears advantageous because (1) regional groundwater flow being usually negligible, the injected hot water is not displaced, (2) thickness of overburde...

Ten successive in situ experimental investigations of hot water storage by a single well and a pair of wells (doublet) were conducted in 1976-1977 at Bonnaud, Jura, in a confined aquifer 2.5 m thick. The injected volumes ranged from 500-1700 m 3. Temperature profiles were measured daily in 12 boreholes distributed along two perpendicular axes within 13 m of the injection well. Individual temperatures were measured by ten thermistors placed in the caprock. The results are discussed and used to calibrate two mathematical models. An axisymmetric model allows the calibration of average values of the parameters, while a three-dimensional model is used to determine their spatial variation in the horizontal plane. The latter model leads to the identification of a nonhomogeneous transmissibility field which fully accounts for both hydraulic and thermal contour curves. The models, which were matched against particular experiments, proved accurate when simulating other periods. Evidence is given of the importance to the recovery ratio of thermal dispersion in the aquifer and of the water content of the caprock. In a final section, experimental results of single well storage at Bonnaud, Campuget, and Auburn are compared with general type curves derived in the companion paper. They prove to yield adequate predictions of water temperature during the production phases.

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