Shale gas - an additional source of energy and problems

Shale gas is a kind of natural gas, it consists mainly of methane and is concentrated in shales.

Shales are called rocks, formed from several layers of parallel low-temperature minerals (chlorite, sericite, actinolite, muscovite, etc.).

These rocks are characterized by the ability to easily split into plates, forming spaces (collectors) between which shale gas accumulates.

Separate collectors are not rich in gas reserves, but, nevertheless, they are quite enough to organize industrial production.

Deposits of shale rocks are available on all continents, which can make any country non-volatile, providing the necessary resources.

The production of such gas at cost is high due to the fact that initially this was due to the opening of large areas, using fracturing technology (hydraulic fracturing) and the continuous drilling of long wells in large quantities, creating cracks for gas evacuation.

Gas production

The first industrial gas production from the oil shale deposit was carried out in the USA.

Later, the technology was improved by combining vertical and horizontal drilling, which allowed to reduce the cost of gas production.

Today, shale gas is mined by drilling vertical and horizontal wells using multi-branches at one depth and multi-stage wells (horizontal) with a take-off length of up to three kilometers.

The technology of extraction of shale gas provides for pumping into the drilled wells a mixture of water, chemicals and sand. There is a hydraulic shock, which destroys the walls of gas collectors, which allows to pump all available gas to the surface.

Horizontal drilling technology uses an innovative 3DGEO method of seismic modeling that combines geological research and mapping with computer processing of information, including visualization.

Drilling a horizontal well must be carried out with strict account of all rules, for example, the correct drilling angle should correspond to the slope of the slate.

Shale gas as a commodity

The cost of gas production is determined by such indicators:

- the content in the hard sands of clay, which is able to absorb the energy of hydraulic fracturing, which increases the amount of chemicals used and is reflected in the cost price;

- Sulfur dioxide content (a lower sulfur dioxide inclusion rate increases the gas price when sold);

- the content of kerogen;

- the cost of production in thick and thermally strong shales related to the Paleozoic and Mesozoic periods;

- an indicator of the content of silicon dioxide (the higher it is, the more fragile the shale and the lower the cost price).

Benefits of mining

- development of oil shale deposits using hydraulic fracturing can be carried out in densely populated areas;

- direct proximity of shale gas fields to end users;

- production takes place without the emission of greenhouse gas.

disadvantages

- With the technology of hydraulic fracturing requires large reserves of water near the fields, the liquid is contaminated and difficult to dispose of;

- Shale wells are less durable in operation than conventional ones;

- drilled wells cut the production rate very quickly - by 30-40% per year;

- about 85 toxic agents are used to extract shale gas, although the exact figures are confidential;

- when gas is extracted, methane is significantly lost, which intensifies the greenhouse effect ;

- profitability of extraction is expedient only if there is a high gas price and demand for it;

- Shale ancient deposits have a high level of gamma radiation, which increases the radiation background as a result of hydraulic fracturing.

Ecology and production of shale gas

With the existing technology, shale gas can not be a worthy alternative to the natural.

However, with careful environmental control, the extraction of gas from shale is possible in sparsely populated areas.