This week, the overall grades of 15 oil and gas stocks are lower, according to the Portfolio Grader database. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Golar LNG Partners’ (GMLP) rating falls to a D (“sell”) this week, down from C (“hold”) the week prior. 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’s (KMI) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). Kinder Morgan is a pipeline transportation and energy storage company. The stock price has dropped 6.6% over the past month, worse than the 1.7% decrease the S&P 500 has seen over the same period of time. The stock’s trailing PE Ratio is 27.80. For a full analysis of KMI stock, visit Portfolio Grader.

Slipping from a D to an F rating, Cosan Limited Class A (CZZ) takes a hit this week. 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. For more information, get Portfolio Grader’s complete analysis of CZZ stock.

The rating of Crescent Point Energy Corp. (CPG) declines this week from a D to an F. The stock gets F’s in Earnings Revisions, Earnings Surprise, Cash Flow and Margin Growth. The stock currently has a trailing PE Ratio of 254.70. To get an in-depth look at CPG, get Portfolio Grader’s complete analysis of CPG stock.

The rating of Goodrich Petroleum Corporation (GDP) slips from a C to a D. 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. Investors seem to agree with the downgrade and have pushed down the share price 15.6% over the past month. As of March 4, 2014, 20.6% of outstanding Goodrich Petroleum Corporation shares were held short. For a full analysis of GDP stock, visit Portfolio Grader.

EXCO Resources, Inc. (XCO) gets weaker ratings this week as last week’s D drops to an F. 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. Share prices fell 8.1% over the past month. As of March 4, 2014, 12.4% of outstanding EXCO Resources, Inc. shares were held short. The trailing PE Ratio for the stock is 46.00. To get an in-depth look at XCO, get Portfolio Grader’s complete analysis of XCO stock.

This week, Calumet Specialty Products Partners, L.P.’s (CLMT) rating worsens to an F from the company’s D rating a week ago. 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. Shares of the stock have been exchanging at an usually rapid pace, twice the rate of the week prior. For a full analysis of CLMT stock, visit Portfolio Grader.

Chevron Corporation (CVX) earns an F this week, moving down from last week’s grade of D. Chevron is an integrated energy company with operations in countries located around the world. For more information, get Portfolio Grader’s complete analysis of CVX stock.

Plains All American Pipeline, L.P. (PAA) is having a tough week. The company’s rating falls from a C to a D. Plains All American Pipeline is involved in interstate and intrastate crude oil pipeline transportation and crude oil terminalling storage activities. To get an in-depth look at PAA, get Portfolio Grader’s complete analysis of PAA stock.

TransCanada Corporation’s (TRP) rating weakens this week, dropping to an F versus last week’s D. TransCanada develops and operates energy infrastructures, including natural gas pipelines. The stock currently has a trailing PE Ratio of 37.60. For a full analysis of TRP stock, visit Portfolio Grader.

This is a rough week for Enbridge (ENB). The company’s rating falls to F from the previous week’s D. 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. Shares of the stock are changing hands at twice the rate they were a week ago. The stock has a trailing PE Ratio of 75.60. For more information, get Portfolio Grader’s complete analysis of ENB stock.

StealthGas (GASS) gets weaker ratings this week as last week’s C drops to a D. 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.

Slipping from a D to an F rating, Ultrapar Participacoes S.A. Sponsored ADR (UGP) takes a hit this week. 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. 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 a full analysis of GEVO stock, visit Portfolio Grader.

This week, PDC Energy (PETD) drops from a C to a D rating. 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 4, 2014, 11.2% 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.