Shale gas is a kind of natural gas, it consists mainly of methane and concentrated in shales.
called shale rock, composed of several layers of parallel low-temperature minerals (chlorite, sericite, actinolite, muscovite, and others.).
These rocks are characterized by the ability to easily split into the plates forming space (collectors), among which shale gas accumulates.
Some collectors are not rich gas reserves, but, nevertheless, they are sufficient to organize commercial production.
shale rocks are on all continents, which can make any country in the volatile, provide the necessary resources.
extraction of this gas at cost price high due to the fact that originally it was associated with the opening of large areas, using hydraulic fracturing technology (hydraulic reservoir) and continuous drilling of long holes in large numbers, creating a crack in them for pumping gas.
Gas
first commercial production of gas from shale deposits in the United States have carried out.Later
technology perfected by combining vertical and horizontal drilling, which reduced the cost of production of gas.
Today shale gas is extracted, carrying drilling vertical and horizontal wells using multiotvodov at the same depth and multi wells (horizontal) with a length of up to three kilometers of removal.
technology of shale gas involves injection wells drilled in a mixture of water, chemicals and sand.There is a hammer, which breaks down the walls of gas reservoirs, which allows to pump to the surface all the available gas.
horizontal drilling technology uses innovative methods of seismic modeling 3DGEO, which combines geological studies and mapping with computer processing of information, including visualization.
horizontal drilling must be carried out with strict regard to all the rules, for example, the right angle drill must match the angle of the formation of oil shale.
Shale gas as a commodity
cost of gas is determined by such indicators:
- content in the hard sands of clay, which is able to absorb the energy of the fracture, which increases the amount of chemicals used and the impact on the cost price;
- content of sulfur dioxide (a low rate of inclusion of sulfur dioxide increases in the price of gas sales);
- kerogen content;
- production costs in thick and thermally strong shales belonging to the Paleozoic and Mesozoic periods;
- an indicator of the content of silica (the higher it is, the more brittle slate and lower cost).
Benefits mining
- mining of oil shale using hydraulic fracturing can be carried out in densely populated areas;
- proximity shale gas to end users;
- production runs without greenhouse gas emissions.
Disadvantages
- when hydraulic fracturing technology requires large supplies of water near the fields, the fluid is contaminated and difficult to be disposed;
- shale wells in operation are less durable than conventional;
- drilled wells reduce the production rate is very fast - by 30-40% per year;
- to extract shale gas, using about 85 toxic assets, although exact figures are confidential;
- the extraction of methane gas is much lost, which increases the greenhouse effect;
- profitability of production is suitable only if high gas prices and demand for it;
- ancient shale deposits have high levels of gamma radiation, which increases background radiation as a result of the fracture.
Ecology and shale gas
With the existing technology, shale gas will not be a viable alternative to natural.
However, with careful environmental monitoring, gas production from shale available in sparsely populated areas.
