Evaluation of recoverable energy potential from enhanced geothermal systems: a sensitivity analysis in a poro‐thermo‐elastic framework

This study presents application of an efficient approach to simulate fluid flow and heat transfer in naturally fractured geothermal reservoirs. Fluid flow is simulated by combining single continuum and discrete fracture approaches. The local thermal nonequilibrium approach is used to simulate heat transfer by conduction in the rock matrix and convection (including conduction) in the fluid. Fluid flow and heat transfer models are integrated within a coupled poro‐thermo‐elastic framework. The developed model is used to evaluate the long‐term response of a geothermal reservoir with specific boundary conditions and injection/production schedule. A comparative study and a sensitivity analysis are carried out to evaluate the capability of the integrated approach and understand the degree by which different reservoir parameters affect thermal depletion of Soultz geothermal reservoir, respectively. Also observed, there exists an optimum fracture permeability after which the reservoir stimulation does not change the recovery factor significantly. Estimation of fluid temperature by the assumption of local thermal nonequilibrium heat transfer between the fracture fluid and the rock matrix gives fluid temperature of about 3°C less than that of estimated by thermal equilibrium heat transfer at early stage of hot water production.     

Ancient Mining and Smelting Activities in the Wadi Abu Gerida Area,Central Eastern Desert,Egypt: Preliminary Results

Old mining and smelting features in the Abu Gerida area have been studied using field observations, microscopy and SEM–EDS to detect the ores that were exploited in antiquity. There are two groups of shafts in the area. The first group encloses secondary copper minerals and is associated with glassy slags containing copper prills. The other group is associated with hematite that was extracted and transferred to a smelting station to the west of the mining site, where iron slags and charcoal fragments are found. These slags are composed mainly of wüstite, fayalite–kirschsteinite and traces of metallic iron. Pottery fragments from this area were dated to the Ptolemaic Period, which may be the age of iron exploitation. Copper might have been exploited earlier.     

Book reviews

Werner Röoll. Indonesien: Entwicklungsprobleme einer tropischen Inselwelt. Stuttgart: Klett, 1979. 206 pp.

Shirley Deane. Ambon: island of spices. London: John Murray, 1979. 222 pp. £5.95.

G. W. J. Drewes (ed. and tr.). An early Javanese oode of Muslim ethics. The Hague: Martinus Nijhoff, 1978. viii, 104 pp. (Bibliotheca Indonesica, 18.)

Tunku Shamsul Bahrin and P. D. A. Perera. FELDA: 21 years of land development. [Kuala Lumpur: Federal Land Development Authority, 1977.] x, 167pp., map.

Urs Ramseyer. The art and culture of Bali, [Translated from the German by Eileen Walliser-Schwarzbart.) Oxford: Oxford University Press, 1977. 266 pp.

J. P. Sarumpaet. Modern usage in Bahasa Indonesia. Carlton: Pitman, 1980. vii, 264 pp.

F. van Anrooij and others (ed.). Between people and statistics. Essays on modern Indonesian history presented to P. Creutzberg. Editorial committee: F. van Anrooij, D. H. A. Kolff, J. T. M. van Laanen, G. J. Telkamp. The Hague: Martinus Nijhoff [for] the Royal Tropical Institute, Amsterdam, 1979. 315 pp. Paper, guilders 39.50./