Over the past few years, “oil and gas well” and “injection well” have increasingly become part of the lingo throughout the state of Ohio. But, what do these terms mean? For individuals who are just beginning to get involved in Ohio’s bourgeoning oil and gas industry, differentiating between all of the numerous technical terms can be a somewhat harrowing experience. A great place to begin gaining a working knowledge of the industry is to understand the difference between the different types of wells used to extract oil and gas and to dispose of production wastes. This post will provide a brief overview of what production and injection wells are, how they operate and how they are regulated by the state.
Production Well
What is it?
A “production well” refers to the type of well used to extract oil or gas from subsurface deposits. Production wells are drilled thousands of feet into the earth directly into oil or gas rich deposits contained in underground formations. Traditionally, vertical wells were utilized to extract oil or gas from one subsurface reservoir. Horizontal drilling was later developed in order to extract oil and gas from multiple reservoirs through the use of one well, which is horizontally angled into the deposit.
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Once the production well is drilled, a technique called “hydraulic fracturing” is used bring the oil or gas to the surface. During hydraulic fracturing, a mixture of water, sand and chemicals called “brine” is injected at a high pressure to fracture the rock, which then releases the oil or natural gas and allows it to flow to the surface.
Why do we use them?
Production wells, especially those using horizontal drilling, turn organic-rich shale plays into hot beds of natural gas and oil production. While the Utica shale is not an oil rich shale, many anticipate that it will be a vast producer of natural gas.
According to the U.S. Energy Information Administration, approximately 27 percent of all electricity generated in the United States in 2013 came from natural gas. The ODNR reports that nearly 100 percent of the natural gas produced in Ohio, remains in Ohio. With the increase in production capacity and the decrease in price per MCF of natural gas compared to coal-generated energy, more and more of the energy we use on a daily basis will come from natural gas. Not to mention that natural gas is much cleaner to burn than coal.
How are they regulated?
The Ohio Department of Natural Resources (ODNR) is the sole regulatory authority over oil and gas operations in Ohio. The ODNR enacts rules to govern the overall operation of production wells, including the permitting, drilling, and spacing of those wells. In addition, the ODNR’s rules provide the framework for reporting production from the wells.
The statutes governing oil and gas operations in Ohio can be found in Chapter 1509 of the Ohio Revised Code.
Injection Well
What is it?
Generally, an injection well is used to place oil and gas production waste, such as brine, deep underground into porous rock formations for storage. While a production well is used to extract oil or gas from the subsurface, injection wells are used to safely dispose of waste generated from those production operations or, in some cases, to increase production from nearby producing wells.
Although there are many types of injection wells, Class II wells are the most commonly referred to in conjunction with oil and gas operations in the Utica shale. “Class II wells” include brine injection wells, annual disposal wells, and enhanced oil recovery injection wells.
How does it work?
During the oil and gas extraction process, brine is utilized to fracture underground formations and enable the oil or gas to flow back to the surface. Injection wells are drilled thousands of feet deep into the earth where the injection fluids are deposited into porous rock formations and stored.
This informational video from the ODNR’s website provides a great illustration of how injection wells work.
Why do we use them?
Because of the mixture of chemicals utilized in this process and the potential contamination from the constituents of production, the remaining brine that flows back to the surface must be disposed of in a manner that preserves the state’s natural resources and the health of its citizens. Generally, injection wells are the safest way to dispose of production waste and protect dinking waters. Injection wells do not deposit production waste into subsurface freshwater reservoirs and are typically drilled thousands of feet below water wells. Additionally, Ohio does not allow the direct disposal of brine into the state’s waters.
According to the ODNR, approximately 98 percent of brine from oil and gas production operations is deposited into various formations deep within the earth. The remaining 2 percent is utilized by local government authorities as ice control on road ways.
How are they regulated?
ODNR has the primary regulatory authority over the Class II injection well program in Ohio. (Several other states are regulated by the U.S. EPA). ODNR regulates the construction and operation of all injection wells in Ohio. ODNR also monitors the injection of waste into these wells and any potential seismic impact the activities may have to surrounding areas.
The regulations governing Class II well operations can be found in Chapter 1501:9 of the Ohio Administrative Code.
