What is ‘Fracking’?
- Hydraulic fracturing is not a new technology and has been used to produce hydrocarbons since 1947 – the first European frack was completed in 1952 in the Soviet Union
- Approximately 2.5million hydraulic fracture jobs have been completed worldwide and 60% of all new oil and gas wells are using the technology
- Hydraulic fracturing has been routinely used in the North Sea and Onshore UK conventional hydrocarbon basins (e.g. East Midlands) for 30+ years
- c. 2,000 onshore wells in the UK and c. 200 have been hydraulically fractured
- The combination of horizontal drilling and hydraulic fracturing have enabled the ‘energy revolution’ in the US
How is a well hydraulically fractured?
- Before any hydraulic fracturing takes place a well has to be drilled into the formation of interest
- The well is constructed with multiple casings (steel tubulars) cemented in place to isolate and protect shallower formations (and any aquifers), with a surface wellhead
- Once the well has been constructed, a ‘frac completion’ may be run, i.e. hydraulic fracturing undertaken
- High-pressure fracture fluid is injected into the wellbore, (using surface pumps) with the pressure above the fracture gradient of the rock
- The two main purposes of fracturing fluid are:
–To extend fractures
–To carry proppant into the formation, the purpose of which is to hold the fractures open to allow the flow of hydrocarbons into the well bore
- The fluid injected into the rock is typically a mixture of water, proppants (sand), and chemical additives.
- Typically 99.5% of fracking fluid is made up of water and sand.
- Hydraulic fracturing of a well may be conducted in a numbers of ‘stages’ or jobs – depending upon the well design and formation characteristics. During fracturing operations various types of monitoring can be conducted to help understand fracture development and propagation (e.g. microseismic)
- Following hydraulic fracturing, a continuous process of well integrity monitoring and management is undertaken to ensure the well integrity envelope is not compromised during its life cycle
Typical hydraulic fracturing equipment
Typical hydraulic fracturing equipment involves storage tanks, mixers, high pressure pumpers and data monitoring units. This equipment is temporary during the short period fracturing operations.