For the current week, the overall ratings of 15 oil and gas stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

Crescent Point Energy Corp. (CPG) earns an F (“strong sell”) this week, moving down from last week’s grade of D (“sell”). In Portfolio Grader’s specific subcategories of Earnings Revisions, Earnings Surprise, Cash Flow and Margin Growth, CPG also gets F’s. The stock has a trailing PE Ratio of 107.40. For more information, get Portfolio Grader’s complete analysis of CPG stock.

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. To get an in-depth look at GMLP, get Portfolio Grader’s complete analysis of GMLP stock.

Cosan Limited Class A (CZZ) earns an F this week, moving down from last week’s grade of D. Cosan is a fully integrated company in the renewable energy and infrastructure segments in Brazil. The stock gets F’s in Cash Flow and Margin Growth. The stock’s trailing PE Ratio is 36.20. For more information, get Portfolio Grader’s complete analysis of CZZ stock.

Goodrich Petroleum Corporation (GDP) experiences a ratings drop this week, going from last week’s C to a D. Goodrich Petroleum explores, develops, produces and acquires oil and natural gas properties. The stock receives F’s in Earnings Growth, Earnings Revisions, Equity and Cash Flow. As of Aug. 15, 2014, 24.9% of outstanding Goodrich Petroleum Corporation shares were held short. To get an in-depth look at GDP, get Portfolio Grader’s complete analysis of GDP stock.

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. As of Aug. 15, 2014, 11.1% of outstanding EXCO Resources, Inc. shares were held short. For more information, get Portfolio Grader’s complete analysis of XCO stock.

The rating of Calumet Specialty Products Partners, L.P. (CLMT) declines this week from a D to an F. 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.

This week, Plains All American Pipeline, L.P.’s (PAA) rating worsens to a D from the company’s C rating a week ago. Plains All American Pipeline is involved in interstate and intrastate crude oil pipeline transportation and crude oil terminalling storage activities. The stock currently has a trailing PE Ratio of 26.70. For more information, get Portfolio Grader’s complete analysis of PAA stock.

The rating of TransCanada Corporation (TRP) slips from a D to an F. TransCanada develops and operates energy infrastructures, including natural gas pipelines. To get an in-depth look at TRP, get Portfolio Grader’s complete analysis of TRP stock.

Enbridge (ENB) earns an F this week, falling from last week’s grade of 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. The stock’s trailing PE Ratio is 32.90. For more information, get Portfolio Grader’s complete analysis of ENB stock.

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

Ultrapar Participacoes S.A. Sponsored ADR (UGP) earns an F this week, falling from last week’s grade of D. Ultrapar Participacoes is engaged in the fuel distribution and chemical businesses in Brazil. For more information, get Portfolio Grader’s complete analysis of UGP stock.

The rating of Gevo (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. To get an in-depth look at GEVO, get Portfolio Grader’s complete analysis of GEVO stock.

PDC Energy’s (PETD) rating weakens this week, dropping to a D versus last week’s C. 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. For more information, get Portfolio Grader’s complete analysis of PETD stock.

This week, Chevron Corporation’s (CVX) rating worsens to an F from the company’s D rating a week ago. Chevron is an integrated energy company with operations in countries located around the world. To get an in-depth look at CVX, get Portfolio Grader’s complete analysis of CVX stock.

This week, Kinder Morgan, Inc. Class P (KMI) drops from a D to an F rating. Kinder Morgan is a pipeline transportation and energy storage company. The stock currently has a trailing PE Ratio of 34.30. For more information, get Portfolio Grader’s complete analysis of KMI 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.