Oil's been getting significant attention lately -- but just because Brent Crude prices are above $110 doesn't mean that this climb is anywhere near over. For that reason, we're turning to an oil play first. Shares of Berry Petroleum ( BRY) have kicked of 2011 in similar fashion to the rest of the industry, having already climbed nearly 14% since the first trading day of the year. But with a short ratio of 12.4, it could take short-sellers nearly three weeks to close out their positions at current volume levels -- three weeks of added buying pressure that could send Berry significantly higher. Berry is unique in that its reserves are entirely within the U.S., in California, Texas and the Rocky Mountains. As with most petroleum firms, Berry also produces a significant amount of natural gas -- around 32% of production. U.S. oil projects are traditionally more expensive to operate, requiring a higher crude price to justify drilling, but triple-digit oil effectively makes the argument against pricey U.S. terrestrial drilling moot. Even if Berry's acquisitions at the height of 2008's oil boom were poorly timed, the company is finally dusting itself off and freeing up the balance sheet liquidity to invest in new projects and necessary improvements on existing projects. While the company's dividend is far from impressive, increasing cash flows in this environment could lead the way to increased yields and a swift shakeout of short sellers.