Название: Synthesis Gas
Автор: James G. Speight
Издательство: John Wiley & Sons Limited
Жанр: Физика
isbn: 9781119707899
isbn:
World petro-politics are now in place (Bentley, 2002; Speight, 2011a) for the establishment of a synthetic fuels (including a biofuels) industry and, without being unduly dismissive of such efforts, it is up to various levels of government not only to promote the establishment of such an industry but to lead the way recognizing that it is not only a matter of supply and demand but of the available and variable technology. Unfortunately, although there may be sufficient crude oil remaining to maintain the Crude Oil Age (or the Petroleum Age, that is, the age in which the developed countries of the world operate) for another 50 years (Speight, 2011a, 2011b), the time to prepare is now. The world is not yet on the precipice of energy deficiency (as many alarmists claim) but it is necessary that the politicians in the various levels of (national) governments of oil-consuming nations look beyond the next election with an eye to the future. It should also be the focus of the proponents of biofuels production and use to ensure that sufficient feedstocks are available to successfully operate a biofuels refinery thereby contributing alternate fuels to the gradual (but not drastic) reduction of crude oil-based fuels (Speight, 2008; Giampietro and Mayumi, 2009; Speight, 2011a, 2011b). However, it is time for procrastination to cease, since delay will not help in getting beyond the depletion of crude oil and natural gas resources, and various levels of government must start being serious in terms of looking to the future for other sources of energy to supplement and even replace the current source of hydrocarbon fuels.
Figure 1.1 Types of energy resources.
In addition, and in keeping with the preferential use of lighter crude oil as well as maturation effect in the reservoir, crude oil available currently to the refinery is somewhat different in composition and properties from those available approximately 50 years ago (Parkash, 2003; Gary et al., 2007; Speight, 2008; Siefried and Witzel, 2010; Speight, 2011a, 2014a, 2015b; Hsu and Robinson, 2017; Speight, 2017). The current crude oils are somewhat heavier insofar as they have higher proportions of non-volatile (asphaltic) constituents. In fact, by the standards of yesteryear, many of the crude oils currently in use would have been classified as heavy feedstocks, bearing in mind that they may not approach the definitions that should be used based on the method of recovery. Changes in feedstock character, such as this tendency to more viscous (heavier) crude oils, require adjustments to refinery operations to handle these heavier crude oils to reduce the amount of coke formed during processing and to balance the overall product slate (Speight, 2011a, 2014a).
As the 21st century matures, there will continue to be an increased demand for energy to support the needs of commerce industry and residential uses – in fact, as the 2040 to 2049 decade approaches, commercial and residential energy demand is expected to rise considerably – by approximately 30% over current energy demand. This increase is due, in part, to developing countries, where national economies are expanding and the move away from rural living to city living is increasing. In addition, the fuel of the rural population (biomass) is giving way to the fuel of the cities (transportation fuels, electric power) as the lifestyles of the populations of developing countries changes from agrarian to metropolitan. Furthermore, the increased population of the cities requires more effective public transportation systems as the rising middle class seeks private means of transportation (automobiles). As a result, fossil fuels will continue to be the predominant source of energy for at least the next 50 years.
However, there are several variables that can impact energy demand from fossil fuels. For example, coal (as a source of electrical energy) faces significant challenges from governmental policies to reduce greenhouse gas emissions, and fuels from crude oil can also face similar legislation (Speight, 2013a, 2013b, 2014a) in addition to the types of application and use, location and regional resources, cost of energy, cleanness and environmental factors, safety of generation and utilization, and socioeconomic factors, as well as global and regional politics (Speight, 2011a). More particularly, the recovery of natural gas and crude oil from tight sandstone and shale formations face challenges related to hydraulic fracturing. Briefly, hydraulic fracturing is an extractive method used by crude oil and natural gas companies to open pathways in tight (low-permeability) geologic formations so that the oil or gas trapped within can be recovered at a higher flow rate. When used in combination with horizontal drilling, hydraulic fracturing has allowed industry to access natural gas reserves previously considered uneconomical, particularly in shale formations. Although, hydraulic fracturing creates access to more natural gas supplies, but the process requires the use of large quantities of water and fracturing fluids, which are injected underground at high volumes and pressure. Oil and gas service companies design fracturing fluids to create fractures and transport sand or other granular substances to prop open the fractures. The composition of these fluids varies by formation, ranging from a simple mixture of water and sand to more complex mixtures with a multitude of chemical additives. Hydraulic fracturing has opened access to vast domestic reserves of natural gas that could provide an important stepping stone to a clean energy future. Yet questions related to the safety of hydraulic fracturing persist and the technology has been the subject of both enthusiasm and increasing environmental and health concerns in recent years, especially in relation to the possibility (some would say reality) of contaminated drinking water because of the chemicals used in the process and the disturbance of the geological formations (Speight, 2015a).
The danger revealed by the peak energy theory is that the world is approaching an energy precipice in which (apparently) crude oil that is available one year will not be available the next year. On the other hand, the peak energy opponents take a more realistic view in that the depletion of fossil fuels will occur gradually and, and with the current trends in considering other sources of energy, the concept of the energy precipice is not logical (Speight and Islam, 2016).
The most unrealistic variable in the peak energy scenario arises from the misuse of data that supposedly indicate that the world is approaching the energy precipice in which fossil fuel will no longer be available for use as energy sources – the date of the energy precipice is not only wildly speculative but, in many cases, totally unrealistic. Fossil fuel energy sources will undoubtedly reach a depletion point in the future when these energy sources are no longer available – but not at the moment or even in the present century. At the same time, new gas-fired generating units use highly efficient technologies and are supported by abundant gas supplies. As a result, gas is increasingly viewed as the most economical fossil fuel choice for electricity generation for the United States. Finally, a word on reserve estimation. There are a number of different methods by which crude oil and natural gas reserves can be calculated. These methods can be grouped into three general categories: (i) volumetric methods, (ii) materials balance method, and (iii) the decline curve method or production performance method.
The methods designated as volumetric methods represent attempts to determine the amount of oil-in-place by using the size of the reservoir as well as the physical properties of the reservoir rock(s) and the reservoir fluids. In the calculation process, a recovery factor is assumed, using data (and assumptions) from other crude oil and natural gas fields with similar characteristics to the field under evaluation. Based on these assumptions, the estimated amount of crude oil or СКАЧАТЬ