This week, four Oil and Gas stocks are improving their overall rating on Portfolio Grader. Each of these rates an “A” (“strong buy”) or “B” overall (“buy”).

Chesapeake Midstream Partners (NYSE:CHKM) is bumping up its rating from a C (“hold”) to a B (“buy”) this week. 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.

EQT Midstream Partners LP (NYSE:EQM) shows solid improvement this week. The company’s rating rises from a B to an A. EQT Midstream Partners LP provides natural gas transmission, storage, and gathering services in Pennsylvania and West Virginia. For more information, get Portfolio Grader’s complete analysis of EQM stock.

This is a strong week for Cabot Oil & Gas Corporation (NYSE:COG). The company’s rating climbs to A from the previous week’s B. 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.