Shale Gas

Shale gas is natural gas stored in petroleum-rich shale rocks where petroleum is converted into natural gas subjected to high heat and pressure. Shale gas is becoming an important source of natural gas in the United States and in other countries. Major concerns are the cost, effect on environment, complexity, and safety issues of drilling technology, which require both vertical and horizontal drilling of lateral length of thousands of feet. 

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Recent advances in drilling and fracking technologies have made the access to huge deposits of natural gas in shale deposits technically and economically feasible. These are located across the United States and elsewhere [19,20], and thus shale gas production has grown about 48% per year from 2006 to 2010 in the United States. This fact will influence the American and the world energy outlooks for the near future, together with the variation in the oil price [21]. The... 

Figure 4. Comparison of GHG emissions from shale gas and conventional natural gas with low and high estimates of fugitive methane emissions, surface-mined coal, deep-mined coal, and diesel oil time horizon equal to 100 years [27]...

Thomas, C.K. The economic impact of shale gas extraction A review of existing studies. Ecol. Econ. 2011, 70 (7), 1243-1249. 

Santoro, R. Howarth, R.W. Ingraffea, T. Life cycle greenhouse gas emissions inventory of Marcellus shale gas. Technical Report of the Agriculture, Energy, Environment Program, Cornell University, Ithaca, NY, 2011. To be archived and made available on-line. 

Properties and extraction processes Tight-formation gas is natural gas trapped in low-porosity (7 to 12%), low-permeability reservoirs with an average in-situ permeability of less than 0.1 millidarcy (mD), regardless of the type of the reservoir rock tight gas usually comprises gas from tight sands (i.e., from sandstone or limestone reservoirs) and shale gas. Sometimes tight gas also comprises natural gas from coal and deep gas from reservoirs below 4500 m. Shale gas is produced from reservoirs predominantly composed of shale rather than from more conventional sandstone or limestone reservoirs a particularity of shale gas is that gas shales are often... 

Degasification of coal, gas from Devonian shale, gas from tight formations, gas from geopressured zones, gas from biomass and gas from in-situ coal gasification, etc. 

Pyrolysis studies of oil shale, gas phase subtractive investigations of evolved volatiles, and open tubular gas chromatography— vapor-phase IR spectroscopy of shale oil components were carried out in the interfaced vapor-phase thermal analysis laboratory which has been described in detail elsewhere (4,5). A general block diagram of this system is shown in Figure 1. 

In this overview, however, it should be noted that recent developments in the area of sources and production of shale gas (mainly in C1-C3) completely blnr a vision of the future which was already fairly complex to sketch. 

It is known that the efficiency of oil recovery from a field is only about 30% and it was found that the injection of water made more viscous by the dissolutiou of polymers, including biopolymers obtained by fermentation, helps to increase the production of the reservoir. The injection of biodegradable biopolymers for fracturing would contribute toward making the exploitation of shale gas less risky for the environment. 

A gas chromatograph is used to examine the concentration of toxic chemicals from shale gas. The following compounds are suspected to be present with the methane benzene, methylbenzene, parabenzene, and hydrogen sulfide. 

LBI was also well placed to benefit from the emergence of low-cost shale gas (ethane) at that time, to feed the six crackers it had in the USA. They were converted for minimal capital investment, to be able to mn 90 % of the time on ethane. 

The second feedstock factor is the use of coal in China. The quantity is vast and the cost is low, both of these positive factors being offset by logistics (it is stranded coal) and concern about the quality of both the feedstock and the impact of the low quality on the environment. Oil has been the feedstock of choice for most of the world since WWII or earlier, except for a few countries, notably South Africa where political factors forced the development of an entire chemical industry based on coal. It has been remarkable to see the development of a chemical industry in China based on coal in perhaps just 10 or 15 years. Coal to olefins (CTO) is a realily there. Synthesis gas is produced from coal and then used to make methanol, which is then converted to olefins (ethylene or propylene). Coal to olefins is happening fast in China, it is happening widely (over three dozen projects are described), and it is likely to be as significant or more significant than the North American shale gas phenomenon. 

Both of these trends— shale gas and coal to olefins— will likely be impacted by the recent (2014) drop in oil price from over 100/barrel, down to (almost) 45/barrel. Such very low oil prices make shale oil, shale gas, and deep sea drilling less attractive or even uneconomic. 

Bruijnincx PCA, Weckhuysoi BM (2013) Shale gas revolution an opportunity for the production of biobased chemicals Angew Chem Int Ed 52(46) 11980-11987... 

Keywords LCA, Greenhouse Gas, Freshwater, Shale Gas, Hydraulic Fracturing... 

The ISO guidelines specify four phases of an LCA (a) Definition of the goal and scope of a study, (b) Inventory analysis, (c) Environmental impact assessment, and (d) Interpretation. In this study, we employed the methodology described in our previous work on Marcellus shale gas [2]. 

Figure 1 Operations included within the system boundary for the shale gas life cycle. GHG emissions and freshwater consumption associated with operations up to and including gas treatment and processing are allocated to pipeline quality gas (which goes on to the transmission pipeUne) and the natural gas liquid (NGL) coproduct in accordance with their heat content (HHV) transportation, fractionation and disposition of NGL are not included within the scope of this study. GHG emissions and freshwater consumption associated with power distribution are also excluded from the scope of this study.

LCA evaluates environmental impacts in the context of the function of a product, which permits meaningful comparisons of products or activities. In our work, we employ a Tunctional unit of MWh of electricity generated . This permits comparison of the carbon and water footprints of power generated from shale gas with other methods of power generation (e.g. coal power). 

In Table 2 we report the life cycle carbon and water footprints associated with power generated from shale gas, as well as the fraction of gross methane that is emitted to the atmosphere. 

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