What is shale oil and shale gas?
Crude oil and natural gas can also occur in nature in dense clay rocks – so-called petroleum mother rocks. These are often referred to as slate, such as Posidonia slate. Therefore, the term shale oil or shale gas is often used for crude oil or natural gas from such clay rocks. Both do not differ in their formation and composition from crude oil and natural gas from conventional deposits. Significant shale gas potential could exist in Germany, shale oil potential only subordinate. This is the result of the resource estimate within the NIKO project (2016).
Clay rocks are formed by the deposition of fine-grained mineral components in the deep areas of waters with low currents. Under anoxic conditions, larger amounts of organic material can be embedded in these deposits. Organic material (e.g. algae) sinks to the bottom and can be trapped in the sediment by depositing further mineral components. The lack of oxygen prevents the organic material from degrading. In the course of millions of years, mighty sedimentary sequences are formed in this way, which are compressed by the pressure of the rocks on top and can then be described as clay rocks. Through further subsidence, clay rocks reach depths at higher temperatures. Depending on the composition of the organic material, the increase in temperature initially produces mainly crude oil. Later, natural gas is also formed and crude oil that has already been produced can be converted into natural gas. Such clay rocks are called mother rocks. Most of the hydrocarbons formed escape from these parent rocks and can fill conventional deposits. The hydrocarbons remaining in the clay rocks are called shale oil and shale gas.
Shale oil and gas worldwide
Shale oil and gas deposits are often associated with conventional deposits, as the organically rich clay rocks serve as parent rocks. Today, geological basins with a shale oil or shale gas potential or where a potential is probable have been identified on all continents.
Shale gas and shale oil are currently produced in various basins, mainly in North America. The development of shale gas deposits has also begun in China and Argentina. Increasing activity has also begun in Europe in the exploration of possible shale gas deposits. The first exploratory wells were drilled in Poland, England and Germany, among other countries. The search for shale gas is politically supported in England and Poland. In some other European countries, shale gas exploration is banned because of the public debate on possible environmental impacts.
Development of shale gas
The extraction of hydrocarbons from the subsoil generally requires the drilling of potential rock horizons. In this context, state mining authorities in Germany not only examine the technical issues relevant to exploration and production, but also consider various environmental aspects, which include emissions, waste management, water use and disposal as well as nature conservation. The basis for these approval procedures are regulated by the Federal Mining Act and various other federal and state laws and ordinances.