Abstract-Fuel used by heavy duty trucks is a major cost for logistics companies, and therefore improvements in this area are highly desired. Many of the factors that influence fuel consumption, such as the road type, vehicle configuration or external environment, are difficult to influence. One of the most under-explored ways to lower the costs is training and incentivizing drivers. However, today it is difficult to measure driver performance in a comprehensive way outside of controlled, experimental setting. This paper proposes a machine learning methodology for quantifying and qualifying driver performance, with respect to fuel consumption, that is suitable for naturalistic driving situations. The approach is a knowledge-based feature extraction technique, constructing a normalizing fuel consumption value denoted Fuel under Predefined Conditions (FPC), which captures the effect of factors that are relevant but are not measured directly.The FPC, together with information available from truck sensors, is then compared against the actual fuel used on a given road segment, quantifying the effects associated with driver behavior or other variables of interest. We show that raw fuel consumption is a biased measure of driver performance, being heavily influenced by other factors such as high load or adversary weather conditions, and that using FPC leads to more accurate results. In this paper we also show evaluation the proposed method using large-scale, real-world, naturalistic database of heavy-duty vehicle operation.
Summary. This paper presents a case study of four high-pressure gas wells that were perforated overbalanced in heavyweight mud and then evaluated with pressure-transient tests. The surprising result of these tests was the minimal amount of completion damage. The average skin damage calculated from the test data was 2.6, which is much lower than the 12.6 predicted from data available in the literature. The information from this case study gives the completion engineer additional data on which to base decisions when designing perforation operations in high-pressure gas wells. This case study also raises the possibility that completion damage from overbalanced perforating practices decreases as reservoir pressure increases. Introduction An engineer designing a high-pressure gas-well completion has many difficult decisions concerning the selection of the most economical perforating method. To make this selection, the engineer must consider the cost of each method, the probability of mechanical failure, and the resulting well productivity. The methods available in order of preference are shooting the well underbalanced with a casing gun, shooting underbalanced with a through-tubing gun, shooting overbalanced with a casing gun in a clean fluid, or, as a last resort, shooting overbalanced in mud. It is relatively easy to determine the cost of each method and to determine the potential risks of each method; however, it is very difficult to predict each method's influence on the well's productivity. The importance of selecting the correct method of perforating a high-pressure well can be illustrated by a review of the available options. Perforating the well underbalanced with a tubing-conveyed gun is the best option in terms of achieving the maximum productivity from the well. The advantages of this option are deep perforations, with 90' phasing, and the cleaning effect from underbalanced perforations. The major drawback to this system is the reliability problems of running tubing-conveyed guns in deep, hot, high-pressure wells. On one of Conoco's offshore platforms, 50% of the tubing-conveyed perforating guns failed to fire. The next option is perforating a well underbalanced with a through-tubing gun. Although the benefits of underbalanced perforating are obtained with through-tubing guns, the small guns often do not adequately penetrate the casing and formation. We have had several wells that would not flow when perforated with through-tubing guns but then flowed at rates in excess of 7 MMscf/D [200 × 103 std m3/d] when perforated overbalanced with casing guns. The last option, perforating the well overbalanced with mud in the hole, is the most reliable method from a mechanical standpoint and is the least expensive option. Casing guns will penetrate the high-strength casing strings, and the guns can be retrieved to ensure that all the charges fired, The disadvantage of overbalanced perforating is the potential for completion damage. Perforating in a clean brine will reduce the completion damage, but weighted brines cost several hundred dollars per barrel, require special safety precautions, and may cause severe corrosion problems. McLeod and Locke presented analytical methods to predict the productivity of the different perforating methods. The problem with any analytical method is the large number of assumptions required to complete the calculations. The critical assumptions that must be made are the reservoir permeability, kR; the number of effective perforations, np; and the perforation efficiency-length, Lp, and radius, rp. Fig. 1 diagrams perforation geometry. Typical values for these variables have been presented in the literature; however, the data are generally based on low-pressure wells. Little work has been done on determining whether these variables change when the perforating method remains constant and the formation pressure is increased. Additionally, the permeability of these overpressured sands is usually much lower than the permeability encountered in low-pressure sands. This may also be an important factor. Without these data, the engineer can only assume that these variables remain constant at all formation pressures. Pressure-Transient Data Pressure-transient data from four high-pressure gas-well completions indicate that the variables affecting perforation productivity change as the formation pressure increases. The four completions were all perforated overbalanced in heavyweight water-based drilling muds, yet had an average skin value of only 2.6. The average skin value is much lower than the value that would have been predicted in the literature. Table 1 summarizes the actual calculated vs. predicted skin values for these four wells. These data seem to indicate that the completion damage caused by overbalanced perforating is reduced as the formation pressure increases. Table 2 summarizes the pressure-transient results and completion data for these four wells. The only well that had a significant skin value was Well C, which was initially drilled in Feb. 1982 and was plugged and abandoned. The well was then re-entered and completed in June 1985. The majority of the skin is believed to be a result of formation damage that occurred while the well was plugged. The well-test data support this idea and are discussed further in the Appendix. During completion operations, Wells A and B were subjected to significant surge pressure after perforating. After the perforation runs, the tubing string was run with a downhole shut-in valve located above the packer. This valve was run in the closed position, and the tubing was filled with water. When the valve was opened, the well was subjected to a surge pressure equivalent to the reservoir pressure minus the hydrostatic head of water. The skin factor for these two wells proved to be less than those for Wells C and D, but the difference is not significant. Although this would be the preferred method of bringing a well on line, it is not very practical when a permanent completion is run. Despite the overbalanced perforating techniques, the initial skin values in the four wells indicated that good-quality completions were obtained. The completion quality can be determined by a comparison of the calculated value of the crushed-zone permeability, kdp, with values published in the literature. Locke reported that laboratory tests indicated that the crushed-zone permeability should be about 20% of the native reservoir permeability. McLeod indicated that the crushed-zone permeability should fall within 10 to 25% of the native permeability. Both authors believed that these values were for wells perforated under optimum conditions and that the crushed-zone permeability would be reduced further if a well were perforated overbalanced in mud. Laboratory and field data have indicated that the crushed-zone permeability would be as low as 2.5% of the native permeability when a well is perforated overbalanced in mud. The crushed-zone permeability for the four wells tested was determined in the following manner. SPEPE P. 33^
Today heavy duty trucks are designed and optimized towards a limited variance set of usage and for maximum payload. With European Commission's targets for reducing the consumption of fossil energy resources, increasing transport - and fuel efficiency, future trucks-trailers must be easily adaptable for each freight, load and mission. And during the operation phase, the vehicle combination automatically adjusts itself to the actual driving environment in terms of traffic situation, topology, and payload. The TRANSFORMERS project combines a modular approach for mission rightsizing by means of hybridization, truck engine downsizing and a trailer design that addresses simultaneously aerodynamics and load efficiency improvements. The overall goal is to achieve 25% energy load efficiency (in energy/km.tn) in a real world application taking into account the needs to maintain road infrastructure and traffic safety. This paper will give an introduction to the project, pre-standard for a hybrid on demand vehicle and its objectives towards greening surface transport
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