From a macro viewpoint, the shale energy revolution is a fairly recent phenomenon in the history of energy production in the United States. It fuels a significant proportion of the rise in extraction of unconventional resources. Part of this is due to the proportional decrease in easily accessible conventional resources around the globe, as well as the overall growth of energy consumption domestically and globally. A few key factors drove the shale breakthrough: domestic supply and demand drivers, technology advancements that enabled economic feasibility, and a supportive domestic infrastructure, regulatory and policy environment.
Shale gas and oil is trapped in layers of organic-rich sedimentary rock, as water flows carry the fine mud and sediment and organic matter and deposit it in beds.
Over the course of geological ages, increased overburden pressure and heat from deposition of subsequent layers above the organic matter and rock trap the plant and animal detritus and transform it into kerogen and eventually, hydrocarbons. In shale formations, the oil or gas is trapped in the rock in relatively thin layers of horizontal strata; it does not easily flow within the shale layer or into other layers. Shale is a sedimentary rock with very low porosity and permeability, lacking large channels through which hydrocarbons may move about the formation and is devoid of large gaps and pockets within the formation (ExxonMobil Corporation, 2014). For this reason, more economical and technically feasible sources of hydrocarbons have been pursued, even though geologists have known about shale oil and gas for quite some time. The first commercial shale gas well was drilled in 1821, in Fredonia, New York, predating the well-known oil boom of Titusville, Pennsylvania (Trembath, 2011).
Shale resources were poised like a loaded steel trap, waiting for the key enabling technologies to spring into a fit of action and exploitation. People have known of the presence of shale oil and gas for quite some time, dating back to Native
Americans, who referred to it as “rock that burns.” However, it wasn’t until the
1930’s that shale really began to be explored commercially in the Antrim shale of
Michigan. The advent of pipelines, key to the transportation of natural gas, linked the resource with the consuming cities, and by the 1980’s, over 9000 wells had been drilled there (Arthur, Langhus, & Alleman). A series of technologies, used in combination, began to solve the problems of low permeability, thin hydrocarbonbearing pay zones, and geological uncertainty, and thus unlocked the first truly prolific shale play of the present era: the Barnett Shale.
The three main technologies that drove the shale revolution are hydraulic fracturing, horizontal drilling, and seismic imaging and reservoir mapping. The most recent advancement has been made with 3D and 4D seismic, as well as fracturing efficiency, but all of these technologies have existed for many years. Hydraulic fracturing, or “fracking,” was first pioneered in the 1940’s, and adopted in larger scale in the 1950’s (Trembath, 2011) (Arthur, Langhus, & Alleman). By using massive quantities of fluid and sand pumped down hole into the tight shale reservoir rock, a
wedge is driven through the source rock, allowing for the free flow of the previously trapped hydrocarbons to flow into the wellbore. Over time, fracking became refined through research, in the form of slickwater fracks, acid fracks and gravel packing operations in sandface completions, and now multi-stage selective zonal fracking.
Although highly successful in solving the permeability issue, fracking has brought concerns about freshwater consumption, especially in areas of development where stressed aquifers are present.
The second pivotal technology was horizontal drilling, whereby a wellbore can be drilled…