The ratings of 17 Oil and Gas stocks are down this week, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Phillips 66 (NYSE:PSX) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Phillips 66 is an advantaged downstream energy company. It operates through the following businesses segments: Refining and Marketing, Midstream and Chemicals. The Refining and Marketing segment purchases, refines, markets and transports crude oil and petroleum products in the United States, Europe … In Portfolio Grader’s specific subcategories of Earnings Growth and Earnings Revisions, PSX also gets F’s. For a full analysis of PSX stock, visit Portfolio Grader.

This week, PDC Energy’s (NASDAQ:PETD) rating worsens to a D from the company’s C rating a week ago. PDC is an oil and gas company with drilling and production operations in the Rocky Mountains, the Appalachian Basin, and Michigan. The stock gets F’s in Earnings Revisions and Cash Flow. As of Nov. 15, 2013, 13.1% of outstanding PDC Energy shares were held short. To get an in-depth look at PETD, get Portfolio Grader’s complete analysis of PETD stock.

This is a rough week for EOG Resources, Inc. (NYSE:EOG). The company’s rating falls to D from the previous week’s C. EOG Resources is in the business of the exploration, development, production, and marketing of natural gas and crude oil. The stock gets F’s in Earnings Growth, Earnings Momentum, and Margin Growth. The stock price has dropped 7.8% over the past month, worse than the 1.7% decrease the S&P 500 has seen over the same period of time. The stock currently has a trailing PE Ratio of 41.90. For more information, get Portfolio Grader’s complete analysis of EOG stock.

Suncor Energy (NYSE:SU) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Suncor Energy is an integrated energy company in Canada. The stock gets F’s in Earnings Momentum and Earnings Surprise. For a full analysis of SU stock, visit Portfolio Grader.

Enbridge Energy Partners, L.P. Class A (NYSE:EEP) experiences a ratings drop this week, going from last week’s D to an F. Enbridge Energy Partners transports crude oil and natural gas liquids to refineries in the midwestern United States and eastern Canada. The stock gets F’s in Earnings Growth, Earnings Revisions, and Earnings Surprise. Cash Flow and Sales Growth also get F’s. The trailing PE Ratio for the stock is 48.90. To get an in-depth look at EEP, get Portfolio Grader’s complete analysis of EEP stock.

PVR Partners, L.P.’s (NYSE:PVR) rating weakens this week, dropping to a D versus last week’s C. Penn Virginia Resource 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. The stock price has fallen 6.7% over the past month. The stock’s trailing PE Ratio is 100.80. For more information, get Portfolio Grader’s complete analysis of PVR stock.

Slipping from a C to a D rating, Green Plains Renewable Energy, Inc. (NASDAQ:GPRE) takes a hit this week. Green Plains Renewable Energy constructs and operates dry mill, fuel-grade ethanol production facilities. The stock gets F’s in Earnings Growth, Earnings Revisions, and Margin Growth. As of Nov. 15, 2013, 17% of outstanding Green Plains Renewable Energy, Inc. shares were held short. To get an in-depth look at GPRE, get Portfolio Grader’s complete analysis of GPRE stock.

This week, Chevron Corporation (NYSE:CVX) drops from a C to a D rating. Chevron gives management and technological support to international subsidiaries that operate petroleum, chemicals, mining, power generation, and energy services. The stock also gets an F in Sales Growth. For a full analysis of CVX stock, visit Portfolio Grader.

The rating of ONEOK Partners, L.P. (NYSE:OKS) slips from a C to a D. ONEOK Partners is engaged in the gathering, processing, storage, and transportation of natural gas in the United States. The stock also gets an F in Sales Growth. To get an in-depth look at OKS, get Portfolio Grader’s complete analysis of OKS stock.

Continental Resources, Inc. (NYSE:CLR) earns an F this week, moving down from last week’s grade of D. Continental Resources explores for, develops, and produces oil and natural gas properties in the United States. The stock receives F’s in Earnings Growth, Earnings Momentum, Cash Flow, and Sales Growth. Investors seem to agree with the downgrade and have pushed down the share price 5.2% over the past month. For more information, get Portfolio Grader’s complete analysis of CLR stock.

Teekay Corporation (NYSE:TK) experiences a ratings drop this week, going from last week’s C to a D. Teekay is a provider of international crude oil and petroleum product transportation services. The stock receives F’s in Earnings Momentum, Earnings Revisions, and Earnings Surprise. Equity and Cash Flow also get F’s. For a full analysis of TK stock, visit Portfolio Grader.

Slipping from a D to an F rating, Frontline (NYSE:FRO) takes a hit this week. Frontline owns a fleet of very large crude carriers and Suezmax tankers that transport crude oil and oil products between ports. The stock gets F’s in Earnings Revisions, Equity, Cash Flow, and Sales Growth. As of Nov. 15, 2013, 12.7% of outstanding Frontline shares were held short. For more information, get Portfolio Grader’s complete analysis of FRO stock.

This week, Endeavour International Corporation (NYSE:END) drops from a D to an F rating. Endeavour International is an international oil and gas exploration and production company that acquires, explores, and develops energy reserves. The stock gets F’s in Equity and Cash Flow. Share prices fell 37.2% over the past month. As of Nov. 15, 2013, 20.7% of outstanding Endeavour International Corporation shares were held short. To get an in-depth look at END, get Portfolio Grader’s complete analysis of END stock.

This is a rough week for North European Oil Royalty Trust (NYSE:NRT). The company’s rating falls to F from the previous week’s D. North European Oil Royalty Trust is involved in gas and oil production. It holds overriding royalty rights in certain concessions or leases in the Federal Republic of Germany. The stock also gets an F in Sales Growth. For a full analysis of NRT stock, visit Portfolio Grader.

This week, SandRidge Energy, Inc.’s (NYSE:SD) rating worsens to an F from the company’s D rating a week ago. SandRidge Energy explores and produces natural gas and crude oil. The stock gets F’s in Earnings Growth, Earnings Momentum, and Equity. Cash Flow and Margin Growth also get F’s. Investors seem to agree with the downgrade and have pushed down the share price 13.5% over the past month. As of Nov. 15, 2013, 10.5% of outstanding SandRidge Energy, Inc. shares were held short. To get an in-depth look at SD, get Portfolio Grader’s complete analysis of SD stock.

The rating of Gevo (NASDAQ:GEVO) slips from a D to an F. Gevo operates as a technology development company for biobutanol. The stock gets F’s in Equity, Cash Flow, and Sales Growth. As of Nov. 15, 2013, 16.4% of outstanding Gevo shares were held short. For a full analysis of GEVO stock, visit Portfolio Grader.

Teekay Offshore Partners L.P. (NYSE:TOO) earns a D this week, falling from last week’s grade of C. Teekay Offshore Partners LP provides marine transportation and storage services to the offshore oil industry. The stock also rates an F in Sales Growth. For more information, get Portfolio Grader’s complete analysis of TOO 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.