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With West Texas Intermediate crude holding above $90 and the price of natural gas back over the $4 handle for the first time in years, U.S. oil-field services stocks finally have started to rebound. The emergence of hydraulic fracturing certainly has played a part in this turnaround, as the United States is starting to emerge as a net exporter of energy products to the rest of the world.

In a new report, the energy analysts at Jefferies make the case that the bigger service providers ultimately will see the largest benefit from the surge in domestic production. As the U.S. land services market gives way to that much more of a spot market, there appears to be inefficiencies of operation that can undermine operating margins, even relative to contracted relationships that may not have the same manufacturing efficiency of 24-hour/7-day operations. Simply put, the bigger, the better.

Here are the oil-field services stocks to buy from Jefferies.

Superior Energy Services Inc. (NYSE: SPN) leads off the list. Superior provides specialized oil-field services and equipment to oil and gas companies, and it spiked higher on big trading volume last week. Jefferies has a price target of $33. The Thomson/First Call consensus estimate is $32.

U.S. Silica Holdings Inc. (NYSE: SLCA) is stock to buy. Providing the material used in hydraulic fracturing, or fracking, has driven revenues substantially. The Jefferies price target is $25. The consensus estimate is $24.50.

Pioneer Energy Services Corp. (NYSE: PES) is a small cap name that makes the grade. The Jefferies price target is $9. The consensus target is higher at $10.

Helmerich & Payne Inc. (NYSE: HP) announced solid fiscal second-quarter results last week. An expected increase in natural gas drilling this summer could drive revenues even higher. The Jefferies price objective is $74. The consensus is lower at $71. Either target would represent a substantial move higher from current levels.

Ensco PLC (NYSE: ESV) broke above its 200-day moving average and has traded well lately. The Jefferies price target is $72. The consensus estimate is at $70.

National Oilwell Varco Inc. (NYSE: NOV) makes the Jefferies list and is also a top holding for billionaire T. Boone Pickens. The Jefferies price objective for the stock is $85. The consensus is also $85. This could be a top stock to buy for investors. A move to the target price would represent a 30% gain from current trading levels.

Cameron International Corp. (NYSE: CAM) first-quarter earnings missed estimates due to slower North American activity levels, but year-over-year earnings were up 29.6%. The Jefferies price target is $75, while the consensus is close at $74.50.

Halliburton Co. (NYSE: HAL) is one of the favored big three at Jefferies. Halliburton has among the largest exposure to North America, with 56% of annual revenues derived there. The Jefferies target for the stock is $49, but the consensus is slightly higher at $50.

Schlumberger Ltd. (NYSE: SLB) is another industry giant and it wraps up the Jefferies stocks to buy. With revenue gains from around the world, Schlumberger is a solid long-term portfolio holding. The Jefferies target price is $86. The consensus target is higher at $91.50.

With continued growth of hydraulic fracturing, as well as an increased focus on the oil industry as helping to provide jobs in the United States, business should continue to improve. Investors may want to add multiple names for the Jefferies list to their portfolios, with a focus on the larger market cap names.