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) 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.

Kinder Morgan, Inc. Class P (KMI) ratings are on the decline this week as the company earns an F (“strong sell”). Last week, it received a D (“sell”). Kinder Morgan is a pipeline transportation and energy storage company. At $32.30, the stock is below the 50-day moving average of $33.06. The stock currently has a trailing PE Ratio of 27.40. For more information, get Portfolio Grader’s complete analysis of KMI stock.

This week, Cosan Limited Class A (CZZ) drops from a D to an F rating. 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, twice the rate of the week prior. The stock has a trailing PE Ratio of 33.70. For a full analysis of CZZ stock, visit Portfolio Grader.

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 trailing PE Ratio for the stock is 96.90. For more information, get Portfolio Grader’s complete analysis of CPG stock.

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. The stock receives F’s in Earnings Growth, Earnings Revisions, Equity and Cash Flow. As of March 28, 2014, 29.3% 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.

Slipping from a D to an F rating, EXCO Resources, Inc. (XCO) takes a hit this week. 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 28, 2014, 15.8% of outstanding EXCO Resources, Inc. shares were held short. The stock’s trailing PE Ratio is 46.90. For a full analysis of XCO stock, visit Portfolio Grader.

Calumet Specialty Products Partners, L.P. (CLMT) earns an F this week, falling 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.

The rating of Chevron Corporation (CVX) declines this week from a D to an F. Chevron is an integrated energy company with operations in countries located around the world. For a full analysis of CVX stock, visit Portfolio Grader.

This is a rough week for Plains All American Pipeline, L.P. (PAA). The company’s rating falls to D from the previous week’s C. 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.

The rating of TransCanada Corporation (TRP) slips from a D to an F. TransCanada develops and operates energy infrastructures, including natural gas pipelines. The trailing PE Ratio for the stock is 27.00. For a full analysis of TRP stock, visit Portfolio Grader.

Enbridge’s (ENB) rating weakens this week, dropping to an F versus last 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. The stock has a trailing PE Ratio of 80.30. For more information, get Portfolio Grader’s complete analysis of ENB stock.

This week, StealthGas’ (GASS) rating worsens to a D from the company’s C rating a week ago. StealthGas offers marine transport services for liquefied petroleum gas producers and users. The stock gets 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.

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

This is a rough week for Gevo (GEVO). The company’s rating falls to F from the previous week’s 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.

PDC Energy (PETD) earns a D this week, falling from last week’s grade of 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. As of March 28, 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.