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Microfracture and Matrix Permeability in Shales Using Mercury Injection Capillary Pressure

IP.com Disclosure Number: IPCOM000240188D
Publication Date: 2015-Jan-09

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MICROFRACTURE AND MATRIX PERMEABILITY IN SHALES USING MERCURY INJECTION CAPILLARY PRESSURE


1.Background Technology


1.1 Sedimentary Rocks


[0001]Sedimentary rocks commonly are formed from eroded fragments of other rocks. Clastic rocks, such as sandstone and shale, are composed of discrete fragments of other rocks and form when pre-existing igneous, sedimentary, or metamorphic rocks are exposed and weathered. Eroded sediments can be transported long distances by streams or ocean currents before they are deposited. Burial by other sediments and precipitation of chemical cements causes sediments to become lithified.


[0002]Sandstones, a common type of clastic rock, consist of grains, material filling the spaces between the grains (matrix and cement), and empty spaces remaining between the grains (pores). Grains are typically quartz and feldspar, with minor rock fragments and other particles. Grain diameter commonly ranges from 0.06 to 2 mm. Matrix consists of fine- grained clays and silts. Cement consists of minerals precipitated in pore space, most commonly quartz and calcite. Shales are composed of clay minerals and silt-sized particles, commonly composed of quartz or carbonate.


[0003]Sedimentary rocks with biological origins generally fall into a category called carbonate rocks. Most carbonate sediments are deposited close to their source, typically in marine settings, or even in situ, for example, in coral-reef complexes. Limestone and chalk are examples of carbonate sedimentary rocks. Carbonate rocks consist of grains, cements and pores and they are most commonly composed of calcite and/or dolomite.


1.2 Shale Gas and Shale Oil


[0004]Shale gas and shale oil (also known as oil-bearing shales)have become "game changers" in the US energy market. Shale-gas production increased from 1.10 × 1010 m3 [0.39 Tcf] in 2000 to 1.38 x 1011 m3 [4.87 Tcf] in 2010, or 23% of the U.S. dry gas production. Shale-gas reserves increased to about 1.7 x 1012 m3 [60.6 Tcf] by year-end 2009, when they

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comprised about 21% of US natural gas reserves. Technically recoverable US gas-shale resources are estimated at 2.44 ×1013 m3 [862 Tcf]. Kuuskraa et al. (2011) examined shale-gas resources in the rest of the world, and estimated technically recoverable volumes of 1.63 × 1014 m3 [5,760 Tcf] in 48 shale-gas basins in 32 countries. This amount, combined with US reserves, conservatively increase the world's gas reserves by 40%. Kuuskraa, V., Stevens, S. Van Leeuwen, T., and Moodhe, K., 2011, World shale gas resources: An initial assessment: U.S. Energy Information Administration, Department of Energy, Washington, D.C., 365 p.


1.3 Terminology


[0005]Shale gas is natural gas produced from shale. Shale gas has become an increasingly important source of natural gas in the US over the past decade, Shale gas potential is being investigated outside the US as well- in Canada, Europe, Asia, Australia, and elsewhere.


[0006]Shale is the...