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

Crescent Point Energy Corp.’s (CPG) rating falls this week to an F (“strong sell”), down from last week’s D (“sell”). In Portfolio Grader’s specific subcategories of Earnings Revisions, Earnings Surprise, Cash Flow and Margin Growth, CPG also gets F’s. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. The stock’s trailing PE Ratio is 109.50. To get an in-depth look at CPG, 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. Shares of the stock have been trading at an exceptionally rapid pace, up fourfold from the week prior. For a full analysis of GMLP 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 fully integrated company in the renewable energy and infrastructure segments in Brazil. The stock gets F’s in Cash Flow and Margin Growth. Shares of the stock have been changing hands at an unusually rapid pace, up 589.9% from the week prior. The stock currently has a trailing PE Ratio of 38.60. 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 May 30, 2014, 33.1% of outstanding Goodrich Petroleum Corporation shares were held short. Shares of the stock are being traded at a very rapid pace, up 658.2% from the week prior. To get an in-depth look at GDP, get Portfolio Grader’s complete analysis of GDP stock.

The rating of EXCO Resources, Inc. (XCO) declines this week from a D 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 May 30, 2014, 12% of outstanding EXCO Resources, Inc. shares were held short. 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 receives F’s in Earnings Growth, Earnings Momentum and Earnings Revisions. Cash Flow and Margin Growth also get F’s. For more information, get Portfolio Grader’s complete analysis of CLMT stock.

Plains All American Pipeline, L.P. (PAA) earns a D this week, falling from last week’s grade of C. Plains All American Pipeline is involved in interstate and intrastate crude oil pipeline transportation and crude oil terminalling storage activities. Shares of the stock have been trading at an exceptionally rapid pace, up threefold from the week prior. For a full analysis of PAA stock, visit Portfolio Grader.

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. Shares of the stock have been changing hands at an unusually rapid pace, three times the rate of the week prior. The trailing PE Ratio for the stock is 29.80. For more information, get Portfolio Grader’s complete analysis of TRP stock.

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. Trade volume is up 615% from the previous week. The stock has a trailing PE Ratio of 69.70. To get an in-depth look at ENB, 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. For more information, get Portfolio Grader’s complete analysis of GASS stock.

Ultrapar Participacoes S.A. Sponsored ADR (UGP) gets weaker ratings this week as last week’s D drops to an F. Ultrapar Participacoes is engaged in the fuel distribution and chemical businesses in Brazil. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. For a full analysis of UGP stock, visit Portfolio Grader.

This week, Gevo’s (GEVO) rating worsens to an F from the company’s D rating a week ago. Gevo operates as a technology development company for biobutanol. The stock gets F’s in Equity, Cash Flow and Sales Growth. As of May 30, 2014, 11.7% of outstanding Gevo shares were held short. Trade volume is up 1155.7% from the previous week. To get an in-depth look at GEVO, get Portfolio Grader’s complete analysis of GEVO stock.

Slipping from a C to a D rating, PDC Energy (PETD) takes a hit this week. 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 May 30, 2014, 11.5% of outstanding PDC Energy shares were held short. For a full analysis of PETD stock, visit Portfolio Grader.

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. Shares of the stock have been changing hands at an unusually rapid pace, four times the rate of the week prior. To get an in-depth look at CVX, get Portfolio Grader’s complete analysis of CVX stock.

This is a rough week for Kinder Morgan, Inc. Class P (KMI). The company’s rating falls to F from the previous week’s D. Kinder Morgan is a pipeline transportation and energy storage company. The stock currently has a trailing PE Ratio of 29.30. 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.