Minggu, 12 Februari 2017

When everyone’s doing something unconventional, isn’t it conventional? As in monetary policy and in lifestyles, so in oil –Robin Mills 

Since June 2014, oil price has a decrease over and over and it was claimed because of the success of the exploration, extraction, and development of U.S’s shale gas resources. According to Energy Information Administration of U.S Government (2015), per November 2014 there is significant increase of U.S production compare to previous month into year (Figure 1). So, it is important to know more about Shale Gas. 

Figure 1. Production and Import Minyak Mentah in U.S. 

Shale gas refers to natural gas that is trapped within organic-rich shale formations. Shale itself is a sedimentary rock made up predominantly of consolidated clay and silt-sized particles. Shales are deposites as mud in the queit waters of tidal flats, deep-water basins, and similar low-energy depositional environments. Algae, Plant, and animal-derived organic debris becomes mixed in when these very-grained sediments are deposited (Council of Canadian Academic, 2014). Just like conventional gas, most of the shale gas produced is thermogenic methane. It may contain small amounts of other gases (e.g., ethane, butane, pentane, nitrogen [N2], helium, carbon dioxide [CO]) and impurities. Like conventional gas, shale gas can also be wet (contains commercial amounts of natural gas liquids like ethane and butane) or dry (contains very little or no natural gas liquids). Thermogenic methane can be differentiated from biogenic methane through isotopic analysis. The different between Conventional gas and Unconventional gas can be seen by their reservoir. Conventional gas reservoir are created when natural gas migrates toward sthe Earth’s surface from an organic-rich source formation into a permeable reservoir rock, where it is trapped by an overlying layer of lowpermeable rock. Wherease shale gas resources form and trapped within the organic rich shale source rock. The low permeability of the shale greatly inhibits the gas from migrating to more permeable reservoir rocks. Over the past decade the combination of Horizontal drilling and hydraulic fracturing has allowed access to produce shale gas that were previously need more cost to produce. As an American Petroleum Institute said in “Freeing Up Energy – Hydraulic Fracturing : Unlocking America’s Natual Gas, 2014” that Hidraulic Fracturing is a known technology and has been used for at least 60 years. It has helped produced more that 600 trillion cubic feet of natural gas and 7 billion barrels of oil. Without horizontal drilling and hydraulic fracturing, shale gas production would not be economically feasible, because the gas would not flow at economic rates. 

Sources : Statoil, Shale Gas Play, 2011. Council of Canadian Academic, Environmental Impact of Shale Gas Extraction in Canada, 2014.

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