How Petroleum and Natural Gas are Recovered in North Dakota
Marathon Animation of Hydraulic Fracturing: This 7-minute video explains the process of hydraulic fracturing. Video courtesy of Marathon Oil.
- Billions of barrels of oil and natural gas are trapped in rock far below the surface of the Williston Basin.
- For many years, oil companies knew about this supply but were unable to get the oil out.
- In 2006, the first successful Bakken well was drilled in North Dakota using horizontal drilling and hydraulic fracturing.
- Hydraulic fracturing, or fracking, is the process of using pressurized water to fracture, or crack, deep underground rock so that trapped petroleum can be released.
- Horizontal wells are drilled in order to reach the pockets of trapped oil.
- Water makes up about 90 percent of the fracking fluid, and sand makes up about 9.5 percent. The other half-percent consists of chemical additives.
- Some of the water used in hydraulic fracturing is cleaned of chemical and rock debris and is then used to frack additional wells. This is an enormous cost-saver.
- North Dakota is one of nearly 20 states that requires oil companies to list on a public website – www.fracfocus.org. – the chemicals used in the fracking process.
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- The process of hydraulic fracturing includes stringent procedures to protect groundwater supplies.
- In North Dakota, the groundwater sources are shielded by thousands of feet of geologic formations above the fracturing operations.
- Multiple layers of casing and cement are also used for safe well construction and protection of groundwater.
- Wells are closely monitored with modern, high-tech equipment.
- The North Dakota Department of Mineral Resources Oil and Gas Division enforces rules and policies that are some of the strictest of any state in the United States.
- In North Dakota, the groundwater sources are shielded by thousands of feet of geologic formations above the fracturing operations.
- The process of hydraulic fracturing includes stringent procedures to protect groundwater supplies.
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Hydraulic Fracturing
Williston Basin Map: Geographic Representation of Williston Basin.Map courtesy of North Dakota Studies.
- The initial well bore is drilled using a drill pipe and bit.
- After the initial well bore has been drilled, the drill pipe and bit are removed.
- A steel tube, called surface casing, is set inside the well. The tube stabilizes the sides of the well and creates a protective barrier against any underground water reservoirs.
- Cement is pumped in to secure the casing and create a seal to protect groundwater from contamination.
- The well is pressure-tested to make sure there is no seepage.
- The pipe and drill bit are lowered back into the well, and the drilling continues.
- At the appropriate depth, the drill pipe and bit are angled to create a horizontal path.
- More layers of casing and cement are put in place to form permanent barriers along the entire length of the well bore.
- A perforating gun with explosives is inserted into the well to produce cracks in the shale layer.
- The perforating gun is removed, and fracturing fluid (mostly water and sand) is pumped into the well under great pressure, causing fractures deep into the shale.
- The water is removed, but the sand stays to hold the cracks open.
- The gas and oil that had been trapped in the shale then travel from the cracks into the well.
- This process can be done in multiple “stages” along the 10,000 ft lateral – called “multi-stage fracturing.”
Timelapse of drilling & fracking a well: Watch this 2-minute video to see a timelapse of all the machinery, equipment, workers and resources that go into drilling and hydraulic fracturing a well. Video courtesy of Marathon Oil.
- When oil is removed from underground, natural gas also comes to the surface.
- The majority of the natural gas is piped to gas plants, some is used to operate equipment at the well site, and some is flared, or burned.