We demonstrate that room temperature MeV ion irradiation of a glass containing copper oxide initiates nucleation of pure Cu clusters via the inelastic "electronic" component of the ion energy loss, when the latter is above a threshold value. The clusters grow under subsequent thermal annealing, following Lifshitz-Slyozov-Wagner kinetics. The decoupling of nucleation and growth is analogous to that occurring in the photographic process. It allows total control over the cluster density, average size, and size distribution.

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In many cases of oil production, it becomes necessary to activate wells by a bottomhole pump to maintain sufficient flowrates to guarantee the profitability of production. A careful selection must be made among different processes, because the poor choice of an activation system could result in problems of reliability or inefficiency, leading to excessive operating costs. The OPUS (Optimal Pumping Unit Search) system, by enabling a rational approach to various aspects of process selection, helps the oil producer to find the processes best suited to the field case considered. processes best suited to the field case considered. On the one hand, OPUS integrates an expert system that synthesizes all the knowledge acquired on different systems such as sucker-rod pumps or progressive cavity pumps, hydraulic piston or jet pumps, submersible electric pumps or gas-lift. This knowledge base is used by an inference engine to make an optimum choice after analyzing all the technical and economic criteria. On the other hand, OPUS controls the use of technical sizing programs that support two-phase flows, and economic programs that support two-phase flows, and economic programs that estimate the unit cost per barrel produced programs that estimate the unit cost per barrel produced with the aid of the processes chosen. This system is now in its industrial operational phase and is successfully being used in various projects phase and is successfully being used in various projects proving its qualities of flexibility and rapidity. proving its qualities of flexibility and rapidity Introduction The very suggestive picture of a flowing well producing thousands of barrels of crude oil all by itself is producing thousands of barrels of crude oil all by itself is rarely found in reality, and hides the general situation where assistance must be used to maintain a sufficient flowrate to guarantee the profitability of production. Among possible solutions such as fracturing or acidizing, infill drilling or water flooding, the one consisting in installing a downhole pump appears to be one of the most direct and effective. In addition this last technique can be implemented in combination with the solutions mentioned above. The Institut Francais du Petrole is carrying out research in this field, including the OPUS project. The aim of this project is to study the entire production cycle, from the downhole pumping process to the storage equipment. It has led to the development of an integrated assistance system for selecting the activation processes best suited to a given field. The system is organized around an expert system and a software for technical and economic evaluation. After a short description of the mock-ups that were built in successive stages, this paper describes the expert system and its environment, gives a typical example of its use, and then presents the new ways in which it is now being implemented. P. 37