Pioneer Natural Resources ($PXD), the $27.5 billion independent oil & gas producer based in Irving, Texas, saw shares trading much higher in Wednesday's action.

Shares for Prioneer spiked over 7 percent in midday trading to $213.75, after the company received a “buy” rating from analysts at Raymond James. It is not hard to see why, either, as the company has presence in some of the US’s most promising shale plays, the Spraberry/Wolfcamp shale located near Midland, Texas.

Pioneer estimates that the Spraberry field contains some 50 billion barrels of oil equivalent, which would make it the largest known shale reserve not only in the US, but also one of the largest in the world. If the 50 billion barrel estimates proves out, Spraberry would be nearly twice as large as the much vaunted Eagle Ford shale, whose reserves are estimated at just over 26 billion barrels.

Much of this has to do with the fact that the Spraberry/Wolfcamp concern has what is called in industry parlance “stacked pay potential,” which simply means that the oil and gas hidden underneath the earth is stacked in various layers of shale. This makes for very nice drilling conditions, as one vertical well can be applied to several formations at once.

While it is common practice for oil companies to exaggerate numbers such as the amount of potential reserves they believe they will unlock from a particular play, other independents who are working in the region have also been giving similar estimates of late, making it more likely that Spraberry could likely become one of the most coveted plays, surpassing not only the Eagle Ford shale, but also others such as the Bakken and Marcellus shales.

Independent drillers and producers have so far been the The spike for Pioneer brought shares of other independents along with it. Diamondback Energy (FANG) was up 6.75 percent to $50, Clayton Williams Energy  (CWEI) gained 5.70 percent to $66.50, and Vaalco Energy (EGY) has all gained over five percent heading towards the closing bell.