Three Oil and Gas stocks are moving up in their overall rating this week, according to the Portfolio Grader database. Every one of these is graded an “A” (“strong buy”) or “B” overall (“buy”).

Chesapeake Midstream Partners (NYSE:CHKM) ups its rating to a B (“buy”) this week after earning a C (“hold”) in the week before. Chesapeake Midstream Partners owns, operates, develops, and acquires natural gas, natural gas liquids, and oil gathering systems, as well as other midstream energy assets in the United States. For more information, get Portfolio Grader’s complete analysis of CHKM stock.

Oiltanking Partners LP (NYSE:OILT) is making headway this week, with the company’s rating improving to an A (“strong buy”) from a B (“buy”) last week. Oiltanking Partners LP engages in the terminaling, storage and transportation of crude oil, refined petroleum products and liquefied petroleum gas. . Shares of OILT have increased 5.1% over the past month, better than the 2.5% increase the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of OILT stock.

The rating of Cabot Oil & Gas (NYSE:COG) moves up this week, rising from a B to an A. Cabot Oil & Gas is an independent company that develops, explores, produces and markets natural gas, and transports, stores, and gathers it for resale. For more information, get Portfolio Grader’s complete analysis of COG stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.