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”).

This week, Chesapeake Midstream Partners (NYSE:CHKM) is showing significant improvement as the company’s rating hops from a C (“hold”) to a B (“buy”). 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.

This week, Oiltanking Partners, L.P. (NYSE:OILT) is making solid headway. The company’s rating improves to an A (“strong buy”) from last week’s B (“buy”) rating. Oiltanking Partners engages in the terminaling, storage and transportation of crude oil, refined petroleum products and liquefied petroleum gas. For more information, get Portfolio Grader’s complete analysis of OILT stock.

This week, Cabot Oil & Gas Corporation (NYSE:COG) pushes up from a B to an A rating. 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.