Two-phase (air-water) flow experiments were conducted in horizontal artificial fractures. The fractures were between glass plates (1 x 0.5 m) artificially roughened by gluing a layer of glass beads of Imm diameter. Three rough fractures were studied: one with the two surfaces in contact, and two without contact. Videotape observations revealed flow structures similar to those observed in two-phase flow in pipes, with structures depending upon the gas and liquid flow rates. The data of flow rates, pressure gradients and saturations were interpreted using the generalized Darcy's law. Relative permeabilities curves were found to be similar to classical curves in porous medium, but not unique functions of saturations. The sum of gas and liquid relative permeabilities were found to be less than one at all saturations.

A three dimensional, multiphase, numerical simulation model of the Cerro Prieto field was developed and used to verify that the present installed capacity (620 MW) can be sustained for 30 years and to evaluate the impact of an 80 MW addition to the installed capacity in the NE-E of the field on the present production areas. Cerro Prieto is the largest known water-dominated geothermal reservoir in the world, with more than 175 wells drilled to date and 17 years of production history. Wells here produce fluids of varying enthalpy, from moderate-temperature water to dry steam. The varying enthalpy and a complex interaction between the reservoir and the surrounding aquifer posed a real simulation challenge. The simulation approach used to reproduce the major features of the initial-state and the production history of the field is discussed in this paper. From this study it was concluded that the field is capable of sustaining its present 620 MW total installed capacity for 30 years and the addition of the proposed 80 MW should have a negligible effect on the present production area.

A new apparatus for measuring steam adsorption-desorption isothermally on rock samples has been installed and initial runs made for rock samples from geothermal reservoirs. The amounts adsorbed measured in these experiments are the same order of magnitude as previous experiments.

An experimental simulation of an actual steam-water geothermal well based on field data obtained in New Zealand is carried out in a two-phase flow facility using dichlorotetrafluoroethane, known commercially as refrigerant 114. The simulation of steam-water flow is accomplished by a similarity theory which is achieved by using appropriate dimensionless numbers; namely, the Mach, Froude, and Reynolds numbers at the flashing front. The theory is used to scale the flow properties from that of water to that of refrigerant 114 in the two-phase region, and permits the prediction of steam-water characteristics in a flowing well, under much reduced pressure and temperature levels. Two experimental series were conducted to confront the similarity theory with actual measurements from a flowing well with significant noncondensable gases. Experimental results using refrigerant 114 indicate that the pressure distribution along the pipe can be predicted accurately in the two-phase region of a geothermal well.

This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile region where longitudinal dispersion and convection take place and a stagnant region where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared to those previously presented in literature by Moench and Ogata, Tang et al., Chen et al., and Hsieh et al. The solution is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., for short times) was carried out. The influence of various dimensionless parameters that enter into the solution was investigated. A discussion of results obtained through the Crump and Stehfest algorithm is presented, concluding that the Crump method provides more reliable tracer concentrations.