Hydraulic Fracturing Definitions
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- Base Water
- water used to formulate fracing fluids. This water can be river water, drinking water, well water or treated wastewater effluent.
- chemicals added to frac fluid formulation to “break” the gels and release the proppant materials. The breakers can work on a time-release and temperature-depended principal, or can be introduced later as an independent fluid. Most breakers are typically acids, oxidizers, or enzymes.
- Crosslinking Agents
- chemicals added to the frac fluid formulation to gel or increase the viscosity of the fluid. Required to keep the proppant materials suspended until they reach the fracturing site.
- Drilling Mud
- Liquid drilling fluid is often called drilling mud. The drilling mud is compound mixture of several chemicals as polymer, oil, water, salt, etc. The drilling mud is changed when it is exposed to downhole condition where there are high temperature and high pressure. The drilling fluid used for a particular job is selected to avoid formation damage and to limit corrosion
- Flowback Water
- murky, salty water from fracing natural gas wells; often high in salinity and total 00 dissolved solids (TDS). It consists of frac fluid that returns to the surface as well as produced water. It is laden with the same fracing chemicals that were pumped into the well, in addition to any unique contaminants that are present in the rock formation water deep below. Flowback water recovery is ~15-40% percent of the volume of fluid that is injected, that is forced down a well, and it flows back over a period of 3-4 weeks after fracing, most of it within 7 to 10 days. More than half of the frac fluid remains in the formation.
- short for Hydraulic Fracturing: the process of pumping water, chemicals and proppant at high pressure down the wellbore in order to break open fissures in gas-bearing shale formations. The process is used to maximize well production rates.
- Fracing Fluids
- the drilling fluids (composed of water and chemicals) used to fracture the well; formulations are proprietary and vary based on the geological characteristics of the formations and the service provider.
- Natural Occurring Radioactive Materials that may be present in the flowback or produced waters.
- Produced Water
- refers to the low volumes of “brine” that come up with the gas or oil over the life of the well; it requires proper treatment before disposal. This naturally occurring water found in the sedimentary shale beds traversed by the wellbore is generally very saline in nature and presents an environmental challenge for drillers.
- sand, ceramic beads or other materials used to “prop” the shale fractures or cracks open, providing a pathway for the gas to flow to the surface.
- Reuse Water
- term applied to treated flowback or produced waters suitable for use in fracing fluid formulation or other well drilling activities.
- Tight Gas
- term used to describe that gas deposits in shale formation are tightly held and will not flow unless the shale is fractured.