FAQ

How are wells drilled?

A well is made by drilling a hole called a wellbore, into the earth. Oil and gas wells can range in depth from a few hundred feet to over 20,000 feet. Metal pipe, called casing, is placed in the well-bore and cement is pumped down the casing. The cement pushes out around the bottom of the casing, and flows up the space between the wellbore and casing, back to the surface. When the cement hardens, it forms a bond between the walls of the wellbore and the outside of the casing. This bond protects groundwater, and oil and gas reservoirs, from contamination. Holes are then made in the casing opposite the reservoir, allowing oil and/or gas to move into the casing, and up to the surface where they are processed and transported to market.

What is oil and natural gas?

Petroleum is a general term for oil and natural gas. Oil and gas are important fossil fuels formed from the decomposition and pressurisation of algae, plankton and other organisms. This process forms hydrocarbons, which are compounds consisting entirely of hydrogen and carbon that are powerful combustible fuels. Individual deposits of oil and gas can also contain other compounds, but it is the hydrocarbons that make them valuable.

What is casing?

Casing is the pipe installed into the hole drilled in the ground that keeps the sides from falling in.

How are wells plugged and abandoned?

When a well is no longer needed, either because the oil or gas reservoir becomes depleted, or because no oil or gas was found (called a dry-hole), the well is plugged and abandoned. A well is plugged by placing cement in the well-bore or casing at certain intervals as specified in laws or regulations. The purpose of the cement is to seal the wellbore or casing and prevent fluid from migrating between underground rock layers. Cement plugs are required to be placed across the oil or gas reservoir (zone plug), across the base-of-fresh-water (BFW plug), and at the surface (surface plug). Other cement plugs may be required at the bottom of a string of open casing (shoe plug), on top of tools that may become stuck down hole (junk plug), on top of cut casing (stub plug), or anywhere else where  a cement plug may be needed. Also, the hole is filled with drilling mud to help prevent the migration of fluids.

How do I find oil or gas production information on a well?

Production (or injection) information on oil and gas wells can be found online. Generally an online production/injection (OPI) program that allows monthly production/injection information by well from 1977 to present can be viewed. Totals by field, operator, and lease can also be obtained, with the capability of saving that information into an Excel spreadsheet.

What is hydraulic fracturing?

Hydraulic fracturing, (also known as hydrofracturing, “fracking”, or “fracing”) is the process of creating small cracks, or fractures, in underground geological formations to allow oil or natural gas to flow into the wellbore and thereby increase production. Prior to initiating hydraulic fracturing, engineers and geologists study and model the physical characteristics of the hydrocarbon bearing rock formations, including the formation permeability, porosity, and thickness. Using this information, the well operator designs the process to keep the resulting fractures within the target formation.

To fracture the formation, fracturing fluids are injected down the wellbore and into the formation. These fluids typically consist of water, sand (proppant), and chemical additives. The pressure created by injecting the fluid opens the fractures. In some applications, sand (proppant) is transported into the fractures by a gel-based fluid that keeps the fractures open to increase the flow of oil or natural gas to the wellbore. The chemical additives serve a variety of purposes, including increasing viscosity, reducing friction, controlling bacteria, and decreasing corrosion.

How is groundwater protected when an oil, gas, or injection well is being drilled?

When a well is being drilled, drilling fluid, a specially designed liquid, is pumped through the drill pipe, and circulated out through the wellbore, and back to the surface. One function of the drilling fluid is to lift rock cuttings out of the wellbore and to the surface. Drilling fluid also serves to cool the drill bit, and to counteract downhole formation pressure keeping reservoir fluids and groundwater from entering the well bore and preventing them from mixing. When a well is completed, casing is cemented in the wellbore, keeping reservoir fluids and groundwater from mixing.

How do the regulations ensure that well stimulation will not contaminate water?

Regulations require rigorous testing and evaluation before, during, and after stimulation operations to ensure that wells and geologic formations remain competent and that drinking water is not contaminated. Regulations require operators to evaluate the casing, tubing, and cement lining of the wellbore borehole to ensure that the well’s construction is more than adequate to withstand operations that are intended to increase the permeability of the hydrocarbon producing formation. In addition, operators are required to analyze the faults, natural fracture zones, and other wells in the area to ensure that they will not cause the migration of fluid to other zones. If there is potential for induced fractures to extend beyond the treated hydrocarbon zone, the regulations impose requirements to help prevent groundwater contamination. The regulations also require operators to monitor and test the well during and after well stimulation treatment to verify that well failure has not occurred.