Horizontal or directional drilling has revolutionized the way the oil and gas wells are being drilled in the Williston Basin. The reason that horizontal drilling is changing the oil and gas business is that a well drilled sideways through a formation that contains oil and gas will produce many more times that of a vertical well. A vertical well will only penetrate a limited area of the productive zone, whereas a well drilled horizontally may penetrate up to 10,000' of the zone. This also means that previously tight shale formations such as the Bakken Formation can result in prolific production.
The Bakken Formation has poor porosity which reduces the ability of the gas and oil to flow out of this horizon. Recently, horizontal drilling of lateral holes combined with hydraulic fracturing ("fracking") has resulted in substantial production from thick formations that have poor porosity. Fracking is a procedure whereby packers (plugs) are set every 250' to 300' and up to ten 2,000 horsepower hydraulic pumps deliver high pressure fluids that contain a high percentage of round ceramic beads are utilized as propellant and keep the fissures and fractures open along the bedding-planes that are created by the high pressure fluids. The fissures and channels created by the high pressure fluid and held open by the ceramic beads that are left behind; provide a pathway to allow the gas and oil to flow into the drill hole.
Two new technologies are currently being used to enhance horizontal drilling:
- Log While Drilling (LWD); and
- Drill String Radar (DST)