A tale of two technologies
Hydraulic fracturing and horizontal drilling are often conflated as one and the same method for extracting natural gas. This is not a complete farse, as the technologies are often “wedded” to achieve optimum access to gas and oil deposits. But why is “fracking” the butt of controversy, and not horizontal drilling? NPR’s Jeff Brady says it’s all in the word – “frack” carries a naughty and blunt connotation, which is useful for activist organizations trying to mobilize supporters. It’s our contention that the buzzword itself is only part of the reason.
Horizontal drilling may not receive much attention because the known environmental impacts – compared to traditional vertical drilling strategies – are fairly minimal: instead of having to construct multiple vertical wells on a site, companies can use a single horizontal drill to tap into nearly a mile of surrounding deposits. Minimizing the number of wells built reduces air pollution, water usage, and is (visibly speaking) less scarring for the land. Moreover, where the deposit may be inaccessible through a direct straight-line drill (i.e lakes or environmentally sensitive areas), horizontal drilling allows access to these reserves without affecting the land above. The productivity of these wells is also approximately 400% higher than vertical wells. A more technical description of the difference between horizontal drilling and hydraulic fracturing can be found in another post, “What is natural gas?”
Horizontal drilling first used for oil
To test the commercial viability of horizontal drilling between 1980-1983, the French company Elf Aquitaine drilled 4 experimental wells in Europe. Oil output and production were significantly enhanced. Note that horizontal drilling was and has predominantly targeted oil, not gas. In the United States, horizontal drilling was previously used to tap conventional reserves, such as the Austin Chalk of Texas’ Giddings Field, North Dakota’s Bakken Shale, and Alaska’s North Slope fields. In the early 1990s, the rate of production and oil recovery increased from 2.5 to 7 times the rate of vertical wells in the Giddings Field. According to the EIA, as downhole drilling motors improved and technical know-how spread, the applications of horizontal drilling began to spread in the 1990s. The technology was (up until very recently) still largely used for oil, not gas:
Less than 1 percent of the domestic horizontal wells drilled were completed for gas, as compared to 45.3 percent of all successful wells (oil plus gas) drilled. 15 of the 54.7 percent of all successful wells that were completed for oil, 6.2 percent were horizontal wells. Market penetration of the new technology has had a noticeable impact on the drilling market and on the production of crude oil in certain regions. (EIA)
Horizontal drilling and shale gas
Based on a rather simple and as yet unfinished scan of current horizontal drilling projects and EIA reports, shale gas deposits cannot be accessed by horizontal drilling alone. Hydraulic fracturing is a necessary companion technology because the targeted gas reserves are locked in inaccessible, dense pockets of rock. Where the practice of horizontal drilling alone does not warrant the sort of hype or concern that “fracking” does, the public eye seems to placed emphasis on fracking technologies, as that is where more of the improbabilities and potential environmental and health effects lie.
Continuous drilling technological advances
Will it always be necessary to pair horizontal drilling with hydraulic fracturing? Not necessarily, though emerging technologies would be expensive to apply to dense shale gas reserves. According to Dr. Scott Line, however, the next advances may allow for less fracking:
The latest experimental development in this regard is utilizing complex well trajectories, with multiple horizontal legs radiating from the main horizontal to increase the surface area contact with the geological resource. This allows for a greater area to be targeted, thus allowing for increased production and a reduced need for fracture stimulation.
For information regarding other types of fracking (i.e waterless fracking), see another post of ours: “LP gas fracking”.