Hydraulic Fracturing – a tried-and-tested production method
The media discussions on unconventional gas production often mention “fracing” – short for “hydraulic fracturing”. This technology is basically nothing new – over one million wells worldwide have been drilled using this method in the last sixty years – and it has been constantly developed.
The fracing method is not just used to produce oil and gas, but also for water wells and in geothermal energy. For 40 years now the technology has also been used in other countries with very high environmental standards, such as Norway.
The fracing method is not just used to produce oil and gas, but also for water wells and in geothermal energy. For 40 years now the technology has also been used in other countries with very high environmental standards, such as Norway.
The basic idea is simple: small artificial fractures are created in pre-defined locations in the subterranean rock using water pressure. This is where the term “hydraulic fracturing” comes from. The cracks are then filled with sand or other agents (so-called proppants) to keep them open and create permeable channels through which the gas can flow to the well and be extracted.
The liquid mixture used for hydraulic fracturing is made up of water and sand (to 99%) as well as a very small quantity of so-called additives. These are chemical additives that ensure that the quartz sand mixes with the water, for instance, so that the cracks generated for the gas to flow through stay open long enough and to ensure no microorganisms reach the reservoir. The actual composition of the mixture depends on the characteristics of the reservoir concerned. Many of the additives used are also contained in day-to-day products such as thickening agents in food, detergents, cosmetics or soaps. However, the concentration of these additives in the fracturing fluid is so low that the fracturing solution is not subject to specific labeling requirements according to the legislation on chemicals and is classified as WGK 1 (water hazard classification 1).
That being said, the fewer additives are used, and the more environmentally friendly they are, the better. For that reason Wintershall supports the development of environmentally friendly fracturing solutions with an even lower number of chemical components.
That being said, the fewer additives are used, and the more environmentally friendly they are, the better. For that reason Wintershall supports the development of environmentally friendly fracturing solutions with an even lower number of chemical components.
Protecting the environment and drinking water
Between the level where gas is being produced and the useable groundwater there are many hundred, often several thousand meters of thick rock strata, so-called cap rock. This impermeable cap rock serves as a natural seal, so that neither gas nor fracturing fluids that remain behind during production can rise up to the groundwater. Most of the fracturing liquid is extracted again and disposed of properly or purified. However, a certain amount remains behind in the rock strata. How much that is depends on the geological characteristics of the reserve. To be more precise: on the permeability of the rock strata.
The drilling is completed within a sealed system of steel tubing and cement casing. The gap between the steel pipes and the rock mass is filled with cement, the impermeability is tested before operations begin and monitored continuously. These precautions ensure that fracturing solutions cannot reach the potable water-bearing strata, neither during nor after drilling operations.
There are reports in the USA that claim that drinking water was contaminated during the production of shale gas. These allegations must be taken very seriously and must be examined thoroughly. These investigations are already underway.
In Germany, however, there is not one single case of the groundwater being contaminated from fracing operations because of a leak in the cap rock or the cement protection, not least because of our high environmental standards.
The drilling is completed within a sealed system of steel tubing and cement casing. The gap between the steel pipes and the rock mass is filled with cement, the impermeability is tested before operations begin and monitored continuously. These precautions ensure that fracturing solutions cannot reach the potable water-bearing strata, neither during nor after drilling operations.
There are reports in the USA that claim that drinking water was contaminated during the production of shale gas. These allegations must be taken very seriously and must be examined thoroughly. These investigations are already underway.
In Germany, however, there is not one single case of the groundwater being contaminated from fracing operations because of a leak in the cap rock or the cement protection, not least because of our high environmental standards.
