This week, the ratings of 15 oil and gas stocks on Portfolio Grader are down. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Golar LNG Partners (GMLP) is on the decline this week, earning a D (“sell”) after receiving a C (“hold”) last week. Golar LNG Partners owns floating storage and regasification units and liquefied natural gas carriers. For more information, get Portfolio Grader’s complete analysis of GMLP stock.

Kinder Morgan, Inc. Class P (KMI) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). Kinder Morgan is a pipeline transportation and energy storage company. The stock price has fallen 7.9% 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 27.60. To get an in-depth look at KMI, get Portfolio Grader’s complete analysis of KMI stock.

The rating of Cosan Limited Class A (CZZ) declines this week from a D to an F. Cosan is a global ethanol and sugar company in terms of production with low-cost, large-scale and integrated operations in Brazil. The stock gets F’s in Cash Flow and Margin Growth. At $10.45, the stock is under the 50-day moving average of $11.96. The trailing PE Ratio for the stock is 32.90. For more information, get Portfolio Grader’s complete analysis of CZZ stock.

The rating of Crescent Point Energy Corp. (CPG) slips from a D to an F. The stock gets F’s in Earnings Revisions, Earnings Surprise, Cash Flow and Margin Growth. The stock has a trailing PE Ratio of 96.80. For a full analysis of CPG stock, visit Portfolio Grader.

This week, Goodrich Petroleum Corporation’s (GDP) rating worsens to a D from the company’s C rating a week ago. Goodrich Petroleum explores, develops, produces, and acquires oil and natural gas properties. In Earnings Growth, Earnings Revisions, Equity and Cash Flow the stock gets F’s. At $14.52, the stock is below the 50-day moving average of $15.57. As of March 21, 2014, 25.7% of outstanding Goodrich Petroleum Corporation shares were held short. Shares of the stock have been trading at an exceptionally rapid pace, up threefold from the week prior. For more information, get Portfolio Grader’s complete analysis of GDP stock.

This is a rough week for EXCO Resources, Inc. (XCO). The company’s rating falls to F from the previous week’s D. EXCO Resources is an oil and natural gas company involved in the exploration, exploitation, development and production of onshore North American oil and natural gas properties. The stock gets F’s in Earnings Surprise, Equity and Cash Flow. As of March 21, 2014, 16.1% of outstanding EXCO Resources, Inc. shares were held short. The trailing PE Ratio for the stock is 46.40. For a full analysis of XCO stock, visit Portfolio Grader.

Calumet Specialty Products Partners, L.P. (CLMT) earns an F this week, moving down from last week’s grade of D. Calumet Specialty Products produces hydrocarbon products in North America. The stock gets F’s in Earnings Growth, Earnings Momentum and Earnings Revisions. Cash Flow and Margin Growth also get F’s. To get an in-depth look at CLMT, get Portfolio Grader’s complete analysis of CLMT stock.

Chevron Corporation’s (CVX) rating weakens this week, dropping to an F versus last week’s D. Chevron is an integrated energy company with operations in countries located around the world. For a full analysis of CVX stock, visit Portfolio Grader.

Plains All American Pipeline, L.P. (PAA) gets weaker ratings this week as last week’s C drops to a D. Plains All American Pipeline is involved in interstate and intrastate crude oil pipeline transportation and crude oil terminalling storage activities. For more information, get Portfolio Grader’s complete analysis of PAA stock.

TransCanada Corporation (TRP) earns an F this week, falling from last week’s grade of D. TransCanada develops and operates energy infrastructures, including natural gas pipelines. The stock’s trailing PE Ratio is 27.00. To get an in-depth look at TRP, get Portfolio Grader’s complete analysis of TRP stock.

The rating of Enbridge (ENB) declines this week from a D to an F. Enbridge is in the business of transportation and distribution of crude oil and natural gas primarily in Canada and the United States. The stock gets F’s in Earnings Growth, Earnings Momentum and Cash Flow. The stock currently has a trailing PE Ratio of 79.90. For a full analysis of ENB stock, visit Portfolio Grader.

Slipping from a C to a D rating, StealthGas (GASS) takes a hit this week. StealthGas offers marine transport services for liquefied petroleum gas producers and users. The stock receives F’s in Earnings Growth, Earnings Revisions, Earnings Surprise and Cash Flow. To get an in-depth look at GASS, get Portfolio Grader’s complete analysis of GASS stock.

This week, Ultrapar Participacoes S.A. Sponsored ADR’s (UGP) rating worsens to an F from the company’s D rating a week ago. Ultrapar Holdings operates in the segment of liquefied petroleum gas (LPG) distribution, light fuel & lubricant distribution, and related business in Southern and Southeastern Brazil, production and marketing of chemicals, and provision of integrated logistics solution services for special bulk cargo. 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 UGP stock.

Gevo (GEVO) earns an F this week, falling from last week’s grade of D. Gevo operates as a technology development company for biobutanol. The stock gets F’s in Equity, Cash Flow and Sales Growth. For more information, get Portfolio Grader’s complete analysis of GEVO stock.

The rating of PDC Energy (PETD) slips from a C to a D. PDC Energy 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 March 21, 2014, 12% 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.

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.