Abstract

Exploration, discovery, and economic development of hydrocarbons in unconventional resource reservoirs in the West Texas Super Basin occurred gradually for decades. Knowledge about the basin and potential of unconventional resources and reservoirs are based on research, data, and information obtained during a century of fieldwork on the basin margins. In the basin, economic activity including drilling, subsurface data collection, completions, and production first targeting water, then minerals, and finally hydrocarbons stored in conventional reservoirs more directly contributed to the knowledge of the hydrocarbon potential for unconventional resource reservoirs.

Unconventional resource reservoirs were discovered and developed in the Spraberry 70 years ago, 50 years before unconventional oil and gas resource reservoirs were defined. The Wolfcamp Shale (Wolfberry, combined Spraberry and Wolfcamp in the Midland Basin) discovery occurred over a decade (late 1990s to late 2000s) by a network of individuals across time, several different companies, and outside events.

Similar to the Spraberry decades earlier, the Avalon (Bone Spring) play in the northern Delaware Basin developed from a traditional siltstone play near the basin center to an unconventional resource reservoir as reservoir grain size decreased toward the basin margins. Still, hydrocarbon saturation remained high on the conventional reservoir margins. In the southern Delaware Basin, the necessity for economic success in failing conventional plays lead an independent to change exploration strategy based on observations from a team evaluating subsurface data and information and knowledge of discoveries and development of unconventional resource plays throughout the United States, including the neighboring Midland Basin unconventional resource reservoir plays. These combined northern and southern Delaware Basin unconventional resource plays (Bone Spring and Wolfcamp) also became known as the Wolfbone. The Delaware Basin movement into unconventional resources also gradually occurred over a decade, 2000–2010, a few years behind the Midland Basin unconventional discoveries and early development. However, the majority of the industry did not have significant involvement, investment, drilling, and subsequent production did not show significant results in either the Midland or Delaware Basins until the middle and second half of the 2010–2019 decade and after early development and production acceleration in other oil-rich, unconventional resources, first in the Bakken, then in the Eagle Ford.

The oil price drop from 2014 to 2016 resulted in a decrease of investment and the number of drilling rigs throughout the United States but less in the West Texas Basin. The percentage of total investment and unconventional oil rigs in the West Texas Basin rose to more than 50% of total domestic industry investment and drilling activity, accounted for 35% of domestic oil production, and was the controlling supply-side factor of world oil price. During the first century (1920–2020) of exploration and production, the West Texas Super Basin has produced 63 BBOE. The United States Geological Society (USGS) and Bureau of Economic Geology estimates are that the discovery of the unconventional resource reservoirs (2000–2019) and future development in the West Texas Super Basin could technically produce twice those reserves during the next half-century.