The popular perception of the “shale revolution’ is that of a sudden technological breakthrough that led to a near-instantaneous change in the approach to oil and gas development in the US. Although, there were individual breakthroughs, these were generally preceded by a significant period of slow progress and focus on production from unconventional reservoirs. The switch to shale development in the Permian Basin is a study in such a process.

The Spraberry sands in the Midland Basin have been a production target since the 1950s. These fine-grained reservoirs generally required hydraulic fracturing to stimulate production, even during its early boom (1951-52). The Spraberry continued to attract interest, with cyclic increases in drilling in periods of high oil prices, notably 1984-85. Over time, companies experimented with increasing the size of the hydraulic fracture jobs applied to the wells and even attempts at horizontal drilling when that technology first became commercial.

Beginning in 2003, there was a new boom in vertical drilling in the Spraberry, with completions often extending into tight mud rocks and carbonates of the underlying Wolfcamp, building on knowledge from other areas regarding production from unconventional reservoirs. This period of the Wolfberry play was driven by small operators, reaching a peak of ~3700 new vertical wells in 2012. Prior to this period, Spraberry production had been relatively flat at 30-40 MMBO per year, but production began climbing after 2007, reaching a peak of ~111 MMBO per year in 2014.

A few hydraulically-fractured horizontal wells were drilled in the Midland Basin before 2010, but horizontal development did not begin until that year, once vertical development had shown the potential of the play. This phase of development was dominated by larger operators, and led to a rapid decline in vertical drilling and production. By 2015, there were twice as many horizontals drilled as vertical wells, and horizontal production exceeded vertical production for the first time.

There were attempts to approach the development of the Bone Springs sands in the Delaware Basin in a similar fashion in the early 2000s, but it never approached the scale of the vertical development in the Midland Basin. Horizontal development began earlier in the Delaware Basin, and both drilling and production quickly outstripped that in the Midland Basin.