Nine 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 (CHKM) is making progress this week as its rating of C (“hold”) from last week increases to a B (“buy”) rating 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.

Diamondback Energy, Inc. (FANG) is progressing from last week’s rating of B (“buy”) as the company improves to an A (“strong buy”) this week. The stock price has risen 5.5% over the past month, better than the 1.3% decrease the Nasdaq has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of FANG stock.

U.S. Energy Corp. (USEG) boosts its rating from a C to a B this week. U. S. Energy explores for oil and natural gas. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. For more information, get Portfolio Grader’s complete analysis of USEG stock.

PVR Partners, L.P. (PVR) gets a higher grade this week, advancing from a C last week to a B. PVR Partners owns and operates a network of natural gas pipelines and processing plants which provide gathering, transportation, compression, processing, dehydration and related services to natural gas producers. Even though the stock was upgraded, it has remained flat from a week ago. The stock’s dividend yield is 2.2%. For more information, get Portfolio Grader’s complete analysis of PVR stock.

Carrizo Oil & Gas, Inc. (CRZO) earns an A this week, jumping up from last week’s grade of B. Carrizo Oil & Gas is engaged in the exploration, development, production and transportation of natural gas and oil, mainly in the United States. At $52.23, the share price is approaching the 52-week high of $52.66. For more information, get Portfolio Grader’s complete analysis of CRZO stock.

Frontline (FRO) boosts its rating from a C to a B this week. Frontline owns a fleet of very large crude carriers and Suezmax tankers that transport crude oil and oil products between ports. For more information, get Portfolio Grader’s complete analysis of FRO stock.

Niska Gas Storage Partners (NKA) gets a higher grade this week, advancing from a C last week to a B. Niska Gas Storage is an independent owner and operator of natural gas storage assets in North America. Investors have pushed the stock price up 10.4% over the past month. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of NKA stock.

Advantage Oil & Gas (AAV) is seeing ratings go up from a C last week to a B this week. Advantage Oil & Gas is actively engaged in the business of oil and gas exploitation, development, acquisition and production. The stock’s price of $4.25 is above the 50-day moving average of $4.08. For more information, get Portfolio Grader’s complete analysis of AAV stock.

This week, Cross Timbers Royalty’s (CRT) ratings are up from a B last week to an A. Cross Timbers Royalty is an express trust in the United States. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. The current dividend yield is 2.4%. For more information, get Portfolio Grader’s complete analysis of CRT 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.