Pioneer Natural Resources (PXD 0.63%) reported a lot of numbers in its third-quarter earnings release. However, one really stood out as an impressive result. That number is the estimated ultimate recovery of some of its recent shale wells, which could top 1 million barrels of oil equivalent over the lifetime of the well.

The estimated ultimate recovery of a well takes current production data and projects how much oil and gas that well will produce over its lifetime. The more a well produces, the higher the returns for drillers like Pioneer Natural Resources. In the case of this past quarter's numbers, many of the horizontal wells it drilled into the Wolfcamp A and B in Texas' Permian Basis are expected to exceed 800,000 barrels of oil equivalent. Further, as the slide below shows, cumulative recoveries are on a pace that could exceed 1 million barrels of oil equivalent.

Source: Pioneer Natural Resources Investor Presentation

That's pretty significant because the economic returns of 1 million barrel of oil equivalent well can be more than 100%, depending on well costs, oil content, and commodity prices. Returns like those enable oil and gas companies to turn drilling rigs into money printing presses. As the following slide details, the more oil and gas that Pioneer's wells can produce, the higher the returns.

Source: Pioneer Natural Resources

One of the reasons that Pioneer's returns are so good here is that its wells are oil rich -- nearly three quarters of the production is oil. That can make a big difference. Another producer targeting the Wolfcamp, EOG Resources (EOG 0.67%), has an average well that's split evenly with natural gas, liquids, and oil. Despite high estimated ultimate recoveries, EOG Resources only expects to see after-tax rates of return between 30% and 60% this year depending on where it drills and its well costs.

Not that 60% after tax returns are anything to sneeze at. These results only appear weaker when considering that EOG Resources enjoys triple-digit after-tax returns at its Bakken and Eagle Ford operations. If anything, the results Pioneer Natural Resources saw this quarter suggest that there is similar potential for companies like EOG Resources to find high-returning places to drill in the Permian.

Overall, the Permian Basin is turning out to be a place that energy companies can turn to in an effort to drive oil production growth. Another example here is Devon Energy (DVN 0.84%). Last quarter it used its position in the Permian to drive 36% oil production growth in the U.S. That's only the beginning for Devon, which has been able to expand its future drilling opportunities by 400% since last year and is now accelerating drilling in the Permian.

Given Pioneer's impressive results, investors should keep an eye on are what EOG Resources and Devon Energy have to say about the Permian in their upcoming earnings reports. Devon reports tomorrow and EOG reports the following day. If either company states that wells in the Permian are outperforming expectations, it would suggest the play could be even better than expected and can really drive future returns for both companies.

American oil and gas companies continue to find and produce more oil than we ever thought possible. That is creating a boom that shows no signs of letting up. The great news is that there's still plenty of time for investors to get involved as new plays and zones seem to be emerging all the time.

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