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What happens to hydrofracturing fluids and the bedrock is cracked?
When bedrock is cracked during the hydrofracturing process, the fluids injected to fracture the rock can escape into the cracks, potentially contaminating groundwater. This can pose a risk of groundwater pollution with chemicals used in the fracking fluid and from the release of naturally occurring substances from the rock formations. The extent of the contamination will depend on factors such as the depth of the cracks and the proximity to groundwater sources.
facts about fracturing?
Hydraulic fracturing, also called fracking, hydrofracking, and hydrofracturing, is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid.
How do you hydro fracture a water well?
Hydrofracturing is a technique first applied to oil and gas wells. Water wells which are drilled into rock can be treated with this to increase their water yield, or renew a low yielding well. In a well, water flows from fissures into larger and larger fissures. A well is a collection point for water to flow from the cracks in the rock, collect, and be pumped out. The production rate of a well depends upon how many water bearing fissures connect to the well. Over time, these cracks can become blocked, with silt, bacterial growth in the rock that creates crusts, oxidations, and precipitations of minerals. * In hydrofracturing, a device is lowered into a well and a collar is pumped up. Then, high pressure water is used to fill the well and pressurize it to up to 3-4000 PSI. This essentially backflushes the well, by forcing water into the cracks, opening them up, and flushing out the contaminants. It also may establish new fractures through which water can connect and flow into the well. Sometimes, chemicals are added to enhance the process. The contents of the well are then pumped out. Hydrofracturing can cause impressive gains to well flows. It typically costs about half as much as drilling a new well...which, itself has only a 50% chance of working better than the well replaced, since it is often drilled into the same formation, and the same things which happened to cause the first well to fail may cause the second to fail, or pump no better, than the first. Proponents of the technique believe that the pressure affects a 100 foot circle of rock around the treated well. In some localities the technique has been banned because of belief that it will adversely affect other people's wells. In most cases, it does nothing, but some people whose wells are near a hydroshocked well have reported it improves their flow.
What is an effective alternative to hydrofracturing oil and gas wells?
Some wells can be produced without fraccing, but the production would be much lower and the well could not be kept on production for a sufficient period of time to pay back the investment. For a well that is producing from a low permeability formation, the well can be drilled horizontally through the formation, for much higher production rates. This is commonly done when fracturing is not feasible, due to an overlying gas cap or underlying water zone. Improved productivity is also possible through injection of acid, which will open up the natural pores through the chemical reactions. Both hydrochloric and hydrofloric acid are used. In many case today, wells are drilled horizontally, and then fractured in sections, to produce the highest productivity. This is referred to as a "zipper frac."
How is oil removed from layers of rock?
Petroleum oil is seldom found as pools in layers between rocks, rather it is normally in the pores of the rocks. Usually there is considerable pressure from the layers of rocks above the oily rock layers so if there is a crack in the rock layers, the oil will seep into the crack - sometimes resulting in oil pooling on the surface as it is squeezed up through the crack to the surface. Mostly however, oil is recovered from the deep layers of oily rock by sinking a shaft into the oily layer and pumping the oil to the surface. Once the oil that will naturally flow into the drilled shaft has been recovered, secondary and tertiary oil recovery methods are used. Some of these include pumping water into the area around where the oil is trapped in the rock to displace the oil with the water. Carbon dioxide may be pumped into the rock from wells drilled around the oil field. The carbon dioxide mixes with the oil and reduces the viscosity to help it flow better, Surfactants may be added to the fluid pumped into the wells to get the oil to not stick to the pores so much and flow to where the well has been drilled. In Hydraulic fracturing (also fracking, fraccing, hydrofracturing or hydrofracking) fluid is pumped under pressure into the well to cause the rocks to fracture in order to make it easier to recover the oil by providing cracks that the oil can flow through instead of having to migrate solely through the pores of the rocks. Most of the time, however fracking is used to assist gas recovery rather than oil recovery.
