Because our operations are diverse – oil and natural gas, onshore and offshore, in varied ecosystems and economies – we research the specific environmental considerations for each project and respond to them individually. In addition, our operations are guided by our Global Environmental, Health and Safety Management System (GMS). This system is built on principles from a number of industry and regulatory sources including the U.S. Occupational Safety and Health Administration, U.S. Environmental Protection Agency, International Labour Organization, and World Bank, and ensures consistency throughout our operations.
Hydraulic fracturing is one of the many steps in the process of drilling and completing most oil and natural gas wells. It is a well-stimulation method used to complete 90 percent of the oil and natural gas wells drilled in the United States. Although the injection process for each well typically lasts only two to three days, the well may produce for 20 years or more.
Commonly known as “fracking,” the stimulation process involves injecting a mixture of water, sand, and a small amount of chemical additives at high pressure into rock formations many thousands of feet below the surface of the earth. The mixture travels inside cement-lined steel casing until it reaches the targeted hydrocarbon-bearing formations, where it creates small fractures that provide a path for trapped oil and natural gas to flow into the wellbore. Hydraulic fracturing makes it possible to recover previously inaccessible oil and natural gas. It extends the life of existing wells and increases the productivity of new wells. This has the effect of reducing the overall number of wells drilled to produce oil and gas. Hydraulic fracturing is often combined with horizontal drilling techniques that enable greater reach within an oil- and/or natural gas-bearing formation from a single well site.
In the last few years, public concerns have been raised that the chemicals used in fracturing fluids may reach ground and surface water supplies. We require our site operators to adhere to strict standards and best management practices to avoid potential environmental impacts during onshore oil and natural gas development. It is not our practice to unnecessarily store fracturing fluids on location. Upon delivery, fracturing fluids are blended on location and pumped, and flowback fluids are captured in steel tanks in our DJ Basin operations (and lined pits in our Marcellus operations) and then properly disposed of according to applicable federal and state laws and regulations. Noble Energy encourages the utilization of environmentally friendly additives. We do not use diesel fuel in our hydraulic fracturing fluids.
Noble Energy is an active member and participant in FracFocus.org, a national hydraulic fracturing chemical registry website. We began voluntarily disclosing the chemicals used at Noble Energy wells through FracFocus.org in mid-2011. Plans are underway to extend FracFocus beyond MSDS reporting.
Well integrity is an initial line of defense against water contamination. The pre-drilling subsurface evaluations conducted by our geologists and engineers are used to determine the depths of formations that contain underground drinking water, the proximity of that water to potential oil and natural gas intervals, and the integrity of the confining layers above and below the target completion zone. Our engineers then design a casing and cementing plan that shows how the well will be constructed. This plan is peer reviewed.
In accordance with best management practices, we utilize multiple strings of casing and cement to prevent gas migration or drinking water contamination. We monitor our pump pressures and fluid returns during the cementing process to ensure adequate coverage of cement across the production and groundwater zones. At various stages of the drilling and completion process, mechanical integrity of the casing and cement is tested to ensure proper installation. During the well construction process, various methods may be used to test the mechanical integrity of the well, such as pressure testing, and various types of wire line logs (including, in some cases, bond logs). We also have well control procedures in place to prevent events, such as loss of well control, from occurring. During the production phase, we continuously monitor flow rates and annular pressures, and we regularly inspect the wellhead assembly and other equipment for leaks, corrosion or damage.
We recognize the importance of water quality and availability. Developing energy resources can require large volumes of water, and significant energy is needed to access, treat and deliver water. With increasing demand for energy and water, we are actively managing and conserving water resources to minimize the impact of our operations.
Noble Energy is committed to a safe, healthful and environmentally responsible work environment. Recognizing the role of our contractors in achieving EH&S excellence, it is intended that our contractors work under conditions and rules that are at least as protective as those governing our own employees. While we do not take control of a contractor’s safety program or relieve any contractor of its safety responsibility, we have developed a separate Contractor Safety Management Plan to achieve compliance with this element of our Global Environmental, Health and Safety Management System (GMS), which includes third party audits. Our plan includes the evaluation of contractor safety performance prior to contract award through the ISNetworld Contractor Database.