Shale is a very common form of sedimentary rock found almost all over the world. This rock is formed from sand, mud, clay and other small particles of minerals such as quartz. Over time, this mixture settles and shrinks to form shale deposits. Such layers are found in rocks of the Paleozoic and Mesozoic periods, which leads us to the fact that they are on average 500 to 700 million years old. In addition to the fact that shale contains natural gas, this rock contains a whole range of useful organic substances that can be used by people for various purposes. Shale is often used for various industrial purposes as a filler for concrete or bricks. Shale layers also serve as an invaluable source of scientific information about the ancient epochs of our planet. The fact is that shale contains a huge number of various fossils that can provide information about different times in the geological history of the Earth.
Shale gas production – how is shale gas extracted?
As with many other methods of mineral extraction, shale gas production technology consists of several crucial stages:
- Exploration;
- Drilling a network of wells;
- Installation of gas collection equipment;
- Creation of hydraulic fractures;
- Gathering and sorting of the products obtained from the wells.
Exploration.
At this stage, the company planning to produce gas evaluates profitability and other indicators related to production and environmental impact. If the environmental standards are in line with the legislation of the region, the process of drilling several test wells begins. Samples will be taken from them to determine the amount of gas contained in the shale. If everything is in order, the company proceeds to the next stage of work.
Drilling
The process of drilling wells in shale gas production is quite different from the standard “just drill a deep hole in the ground”. The thing is that, unlike the traditional method of gas extraction from gas deposits, this scheme does not work with shale gas. The main difference is the fact that shale gas is not in a conventional “gas bubble underground”. It is contained in the tiny pores of the shale formation located horizontally below the surface. Thus, having drilled a vertical well to a certain depth, it is diverted to a horizontal plane and drilled further as long as necessary. Thus, several (possibly dozens) of such wells are created at the production site.
After the direct drilling process, the wells are sealed. This is necessary to prevent the uncontrolled release of gas and other chemicals associated with production. In simple terms, the inserted pipes are insulated with various hermetic seals that do not allow gas to flow to the surface.
