A fundamental characteristic of synthetic lubricating greases is their price; all cost significantly more, sometimes b y several orders o f magni-JSL (1) 34-60 J S L 1-1 Characteristics of Greases 35 mechanisms. Mineral oils intrinsically possess a good balance of properties for lubricant applications. good basic lubricant action through EHD film formation good wettability onto metal good basic corrosion protection general compatibility with engineering environmentsWith greases it is possible t o control further the performance profile with the wide range of thickener systems available; many and varied soap systems, particulate thickeners such as clay and silica and polymeric thickeners such as PTFE and polyurea. Furthermore, mineral oils are compatible with numerous different additive chemicals which significantly enhance basic performance, eg antioxidants, corrosion inhibitors, viscosity improvers, anti-wear additives. In this way mineral oil based greases can provide properties suitable for both versatile, general purposes products and specialised products, giving both an effective balance of performance and cost-efficiency.Despite the wide variety of additives and the effects they impart, it is only possible t o modify, not to change the basic mineral oil properties. The physical and chemical nature of the mineral oil itself, being composed of a complex mixture of rings and chains of hydrocarbon molecules, represents several fundamental limitations. When considering demanding lubrication applications, the following factors can become important: low temperature performance 0 high temperature performance viscosity variation with temperature tendency to oxidise tendency to volatilise @ chemical attack on the hydrocarbons attack/plasticisation by the hydrocarbons on other materials (eg flammability. plastics and rubbers) 36 Coffin J S L 1-1 (4) Performance in oxygen and vacuum High-pressure oxygen can oxidise mineral oil or cause ignition. For this reason Limiting factors for mineral lubricating greases J S L 1-1
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SPE Member Abstract The paper presents a survey of 82 horizontal wells drilled between 1980 and 1992. The survey includes 50 wells operated by Elf-Aquitaine during this period, plus 32 wells operated by partners. It covers more than 20 reservoirs in 13 different countries, onshore and off shore. From the data base generated by the survey, statistical analyses are performed on the type of application, reservoir data, drilling and completion methods. The results are discussed. Production performance and well costs are evaluated and compared to those of conventional wells. Finally, the paper addresses successes and failures, and their causes. A rate of success is evaluated. Introduction Horizontal wells are now fully recognized as an industrial tool for reservoir management, and the level of activity related to horizontal drilling and production systems has shown a constant increase in the last few years. At the same time, the number of scientific and technical publications has followed the same trend. The vast majority of the petroleum disciplines involved: reservoir engineering, drilling and completion, exploitation, etc., have been investigated and well documented, as well as case histories and field developments. Even horizontal well failures are now reported and analyzed. There is, however, little statistical information on results achieved by horizontal wells pertaining, for example, to the rate of failure or to their production performance versus conventional wells. This paper, based on the entire experience of a company which has been among the pioneers of horizontal drilling since 1980, provides statistical information from results achieved in 82 horizontal wells producing 20 different reservoirs. History Elf-Aquitaine, along with a few other companies, started to pave the way for horizontal drilling in the early eighties, drilling one well per year from 1980 to 1983. These wells were drilled in two onshore fields in France and one off shore field in Italy, at various vertical depths up to 3,000 m. In 1986, production results having proved very encouraging, the company felt it had gained sufficient experience to launch its first industrial project, which included five offshore wells. From this time on, horizontal wells became a production tool, and their rate of utilization within the company increased every year, as shown in Figure 1. As reported in the same figure, non operated development projects in which the company had a participation started in 1988, and showed the same increasing trend. In 1992, the company drilled 15 horizontal wells, which represents a 15% share of the development wells. The total number between 1980 and 1992 is 50 operated wells and 32 non operated wells in 13 different countries and 20 different reservoirs. P. 97^
The paper presents a survey of 82 horizontal wells drilled between 1980 and 1992. The survey includes 50 wells operated by EIf-Aquitaine during this period, plus 32 wells operated by partners. It covers more than 20 reservoirs in 13 different countries, onshore and offshore. From the data base generated by the survey, statistical analyses are performed on the type of application, reservoir data, drilling and completion methods. The results are discussed. Production performance and well costs are evaluated and compared to those of conventional wells. Finally, the paper addresses successes and failures, and their causes. A rate of success is evaluated.
Engineering design of the internal combustion engine is under a constant state of evolution which has been driven by many factors. These design changes have led to higher performance requirements from the lubricant, e.g. greater resistance to thermal and oxidative degradation, improved deposit and sludge control, and increased control of volatility. Mineralbased lubricants have traditionally proved successful for the vast majority of automotive applications. The current advances have stretched such products to the limit of their capabilities. In such areas, it has been found that synthetic lubricants offer benefits far outweighing their higher costs, providing clearcut performance benefits for the modern generation of higher‐performance vehicles. The current state of the art is reviewed from both application and chemical standpoints, and future trends are projected in the light of ongoing developments.
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