Fracking Technology

Hydraulic stimulation

To enhance the flow of gas or oil wells and exploit the potential of the deposits more efficiently, wells in production are stimulated hydraulically.

Injecting a fluid under high pressure and at a high flow rate at a specific point inside the well causes cracks to be formed within the rock – the so-called “hydraulic fracturing”. During the fracturing process, the crack measuring about 100 metres in length is filled with proppant agents (bauxite beads) to stop the crack from closing again.

This method of deliberately fracturing the rock increases the drainage area for the gas or crude many times. Gas or oil is then able to drain from the rock into the crack and flow into the well. The now highly permeable flow path to the well means less energy is expended, and the natural gas or oil can therefore be extracted from the deposit more efficiently.

Advantages of hydraulic fracturing

• Improved productivity (higher rate and/or extended productive life at constant levels)
• Increased reserves in the well
• Fewer wells required to extract the natural gas or oil from the deposit (reduced impact on the environment thanks to fewer drilling sites)

Planning and preparation for hydraulic fracturing

Long before the fracturing goes ahead, the fracturing process is planned, and detailed simulations are run. The purpose of the simulation is to optimise the fracturing process, i.e. to achieve the highest possible increase in the flow rate with as little fluid and proppant agent as possible. Once planning is completed, an operating plan is prepared for examination by the mining authority.

Following approval by the mining authority, the operating plan is implemented, the required materials are ordered and personnel is requisitioned. Prior to the actual hydraulic fracture job, a mini fracturing procedure is carried out. The data points returned are used to optimise the design of the fracturing process.

Safety of employees, external personnel and the environment

The safety of personnel and the protection of the environment have top priority. When fracturing is carried out, the following safety measures are put in place: 

• Channel blocks, rainwater retention basins (to prevent accidental leakage of fluids)
• Pressure tests (with a safety margin above operating pressure)
• Relief valves
• Monitoring pressure annuli (real-time monitoring)
• Pre-heating of fracturing fluid (to reduce tension in well string and borehole)
• Safety clothing: jacket, pants, helmet, gloves, shoes, safety goggles, etc.

Composition and disposal of proppant agents

The fluid used with the proppant agents in hydraulic fracturing consists of:

• Water (95%)
• Additives (5%)]

source : http://www.rwe.com