Oil and gas exploration and production major Occidental Petroleum (NYSE:OXY) is having a great run lately. Production is ramping up, thanks to its premier asset footprint in some of the best oil fields in the United States, including the Permian Basin. This led to double-digit earnings growth in the last quarter.

Occidental Petroleum's share price has performed well, as you'd expect. However, no stock is completely without risk. In the energy world, things can (and often do) go wrong. In that light, here are three reasons why Occidental Petroleum stock could fall.

Declining oil prices
As an exploration and production company, Occidental Petroleum is highly dependent on supportive oil prices for growth. When these prices are favorable, revenue and earnings per share get a boost. The other side of this coin is that the company is vulnerable to a downturn in petroleum prices.

Recently, this has played out, enough that it is a concern going forward. The price of West Texas Intermediate crude in the United States in just a few weeks has fallen from over $100 per barrel to its current level near $93 per barrel.

That price of oil is below Occidental's average realized price. Last quarter, Occidental realized an average price of $97.48 per barrel in the United States. This development will affect Occidental's results this quarter, and the impact could be more significant if the trend continues.

Any production disruption in the Permian Basin
Occidental Petroleum has planted its flag in the Permian Basin in a big way. Of course, there's good reason for this, since the Permian Basin is one of the most productive oil fields in the United States. In fact, the U.S. Energy Information Administration said the Permian is one of only three domestic onshore oil fields that produces at least 1 million barrels of oil per day.

However, it's worth noting that Occidental Petroleum generated more than half of its oil production last quarter from the Permian. If there's any sort of disruption there, Occidental would be really exposed.

Other exploration and production companies, such as Anadarko Petroleum (NYSE:APC), have more diversified portfolios. For instance, Anadarko holds onshore operations across the U.S. in fields such as the Eagle Ford and Marcellus shales. Anadarko is also active in the deepwater Gulf of Mexico and holds considerable interests in international developments in Algeria and Ghana. Moreover, Anadarko has built a large liquefied natural gas project in Mozambique, which holds a lot of potential.

This helps insulate Anadarko from unexpected events in any one area. Occidental Petroleum is doing just fine, to be sure, because the Permian is a hugely productive field. But being so dependent on one basin could backfire if things go wrong.

Increasing capital spending
Most oil companies are busy cutting capital spending in light of lackluster returns on new projects over the past year. Instead, they're allocating more capital to increasing cash returns to shareholders. Occidental isn't following suit. Rather, the company continues to allocate more capital into acquiring new acreage and developing existing projects.

This year, Occidental plans to spend $10.2 billion on capital projects. This is up 16% from the $8.8 billion spent last year. This approach could pay off if the new projects work out in the company's favor, but if that is not the case, investors will likely question the higher capital expenditures.

The Foolish takeaway
No company is a risk-free investment, and that's especially true in the energy space, where things can change quickly. Occidental Petroleum is highly dependent on oil prices, and is also overly reliant on one oil-producing area of the country. In addition, it is breaking from the mold of other exploration and production companies by significantly increasing capital spending this year.

These decisions could strike gold for the company if everything materializes as planned, but if not Occidental stock could hit a rough patch in the days ahead.