Hydraulic Fracturing

Hydraulic fracturing, or “fracking,” is the process of pumping high-pressure fluid into a gas or oil well to create cracks in rock formations that then stimulate flow of liquids and gases to the surface. This technology is essential to modern oil and natural gas production, allowing us to drill into hard rock formations that geologists once thought were unproductive. Fracking also allows the reuse of older wells and extends the life of aging reservoirs, making it a vital component in our energy economy.

To design and optimize a hydraulic fracture treatment, engineers must understand the material properties of the rock formation and the in-situ stresses that will affect conductivity and fracture geometry. These features determine how a well performs after it is stimulated and whether it will be economic. To gain this understanding, engineers must perform geologic tests such as cores, well logs and well tests, correlate these data sets with production and fracture-treatment records, and use them to model the fracturing process.

Once a fracturing treatment is designed, it must be carefully pumped in stages. Each stage requires a different combination of water, chemicals and small particles of sand or ceramic materials that are left behind to keep the fractures open. The first stage is the injection phase, where a large volume of fresh, saline, or bore water is combined with the fracturing fluid and injected into the well at very high pressures, up to 690 bar (10,000 psi). The next phase is the fracture propagation stage, where the fracturing fluid is pumped at a lower rate but still at high pressures. Finally, the flow back stage is where a low-pressure volume of saline or bore water is used to flush the proppant and clean up the equipment.

Because the fracturing https://neverbeside.com/tara-energy-services-leading-methane-emissions-reduction-in-oil-and-gas-production-testing/ fluid contains toxic chemicals, all equipment must be tested and all leaks must be repaired before each fracturing treatment. A detailed inventory of all the equipment and materials on location is typically conducted before each fracking treatment, and an inventory is often taken afterward to verify what was actually used. This inventory can reveal any mechanical problems that could cause failures during the treatment.

Air quality is a concern at drilling sites because of the combustion of excess natural gas and the exhaust from heavy machinery. In addition, the chemicals used in hydraulic fracturing can enter the air during transportation to and from a well site and when they are pumped out of a well. Earthworks’ Oil and Gas Accountability Project has worked to get disclosure bills passed in some states, but trade secret laws prevent full disclosure of all chemicals used.

It is not possible to control exactly where induced fractures go, so they can sometimes connect with faults or natural or man-made fractures and carry fluids to other geological formations—including underground drinking water supplies. The EPA’s 2016 assessment of fracking sites found that the agency was often unable to determine with certainty how close fracturing activities were to drinking water sources.