Oil and gas producer EOG Resources (EOG 0.59%) recently reported outstanding fourth-quarter and full-year earnings results, fueled by double-digit, oil-weighted production growth. Let's take a closer look at the three key plays that drove -- and will continue to drive -- the company's exceptional growth.

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The Eagle Ford
South Texas' Eagle Ford shale, where EOG commands a whopping 639,000 net acres, is undoubtedly the biggest driver of the company's growth. The company's performance in the play continues to exceed its expectations, thanks to frac design optimization initiatives that have led to sharp increases in well productivity and initial production rates. 

As a result of these improvements, EOG boosted its estimate for net potential recoverable reserves across its Eagle Ford acreage to 3.2 billion barrels of oil equivalent, or BBOE, up 45% from 2.2 BBOE. For perspective, that's nearly four times the company's estimate of reserve potential when it began drilling in the play four years ago.

The company is now generating after-tax returns of roughly 100% in the western Eagle Ford and 200% in the eastern part of the play, representing one of the most economical drilling programs anywhere in North America. What's more, despite having drilled 1,200 net wells to date, EOG still has 6,000 net wells remaining across its Eagle Ford acreage, representing a 12-year drilling inventory at current activity levels.

The Bakken and Leonard play
Outside of the Eagle Ford, EOG also maintains a strong position in North Dakota's Bakken shale, the other fastest-growing U.S. shale play besides the Eagle Ford. Thanks to new frac technology and downspacing initiatives, the company has reduced Bakken costs substantially and improved its rates of return into the triple digits.

Downspacing and secondary recovery initiatives have also boosted the company's Bakken drilling inventory from seven to 12 years. With 90,000 net acres under its belt, the Bakken should continue to drive strong returns for the company and remain its second-largest contributor to oil production growth over the next several years.

The company's position in the Permian Basin also contributed meaningfully to last year's oil production growth. Based on encouraging initial well results, EOG shifted its focus in the Permian away from the Midland Basin Wolfcamp play and toward the Delaware Basin's Leonard play in the second half of 2013.

The shift in focus is already paying off, as the Leonard play has become the company's highest rate of return asset in the basin, with recent wells delivering high initial production rates comparable to the Bakken and Eagle Ford. EOG will continue to concentrate on the Leonard play in 2014, with an emphasis on more efficient drilling and continued testing of additional prospective zones.

Growth fueling stronger returns
These three plays helped EOG deliver 40% year-over-year growth in crude oil production in 2013, besting the vast majority of its peers. By comparison, Chesapeake Energy's (CHKA.Q) oil production jumped 32% last year, led by its Eagle Ford assets, while ConocoPhillips (COP -0.43%) delivered 31% year-over-year growth from its Eagle Ford, Bakken and Permian operations.

Even more impressive, however, is EOG's long-term track record of 38% annual growth in crude oil and condensate production over the past five years, which is unmatched for a company of its size. This exceptional high-margin growth helped boost the company's return on equity to 15.6% last year, up from 11.8% in 2012, and increased return on capital employed to 12.4%, up from 9.4% in 2012.

With more than a decade's worth of drilling inventory across the Eagle Ford and the Bakken, EOG is well positioned to deliver robust double-digit production growth for several years and to soon become the largest oil producer in the U.S. And with its strong operational performance translating into stellar financial results, EOG should continue to keep its shareholders happy.