According to a recent report from Barclays, global exploration and production spending will reach a record $678 billion this year, representing a 10% increase over 2012 levels.

The bank's forecast, an upward revision from its December 2012 estimate of $644 billion, would mark the fourth consecutive year of double-digit global spending increases since 2009.

Much of the expected increase in global E&P spending is attributed to new projects in the Middle East and other regions in Asia, Barclays added. North American spending, on the other hand, is forecast to grow by a relatively modest 2%.

Barclays' assessment has important implications for one energy subsector: the services companies. Let's check out three of them that may be worth investing in.

Halliburton
In general, the rise in global E&P spending bodes well for the companies that provide the equipment and expertise necessary to exploit shale reserves. One company that's aptly positioned to profit is Halliburton (HAL -0.53%), which, in addition to its dominant position in the U.S., also stands to benefit from the increase in E&P activity outside North America.

In particular, the company's Drilling and Evaluation business, which provides field and reservoir modeling, drilling, evaluation, and precise well-bore placement solutions, stands out as a big potential winner from the increase in E&P spending that Barclays expects in the Middle East and other parts of Asia.

Nuverra (formerly Heckmann)
Next up is Nuverra Environmental Solutions (NESC), formerly known as Heckmann, a full-service provider of water management solutions. Over the next several years, the company stands to benefit from one major trend: the scarcity of water for fracking operations and the need to efficiently recycle and reuse it.

What sets Nuverra apart from some of its competitors, such as Key Energy (KEG) -- a fluid-treatment provider that focuses mainly on water disposal -- is its overarching focus on treating and recycling produced water, as opposed to just disposing it.  

For instance, it owns a stake in a wastewater recycling facility in the Marcellus and is working hard on improving its treatment and recycling capacity. And unlike many of its competitors, Nuverra offers its customers full-service solutions, helping them handle their water disposal and recycling needs throughout the full cycle, from delivery to disposal.

National Oilwell Varco
Another potential winner is National Oilwell Varco (NOV -0.05%), the single largest supplier of rig equipment to the oil and gas industry. Through decades of smart acquisitions, it has grown to become the most dominant, low-cost provider of rig equipment for the world's largest drillers, commanding a whopping 60% market share.  

As CEO Pete Miller has noted, "No well is drilled, nor any drilling rig exists, without some equipment on it from National Oilwell Varco." While there are some short-term headwinds for the company, its longer-term prospects still appear robust. One of the key drivers of future growth should be the rig technology segment, especially its aftermarket services.

Of the more than 150 rigs National Oilwell has delivered since 2005, very few have been returned to the company for major work. Once these rigs start coming back for surveys and other work, the company stands to earn $500 million to $1 billion in additional revenue, assuming $25 million to $50 million per major rig survey, which should continue to drive profitability for at least the next several years.