This week, 16 Oil Gas & Consumable Fuels stocks are worse, according to the Portfolio Graderdatabase. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

PetroChina Company Limited Sponsored ADR (PTR) gets weaker ratings this week as last week’s D drops to a F. PetroChina Company Limited Sponsored ADR explores for, develops, produces, and sells crude oil and natural gas, and is engaged in refining crude oil and petroleum products. The company also gets F’s in sales growth, earnings surprise, and free cash flow. For more information, get Portfolio Grader’s complete analysis of PTR stock.

World Fuel Services Corporation (INT) earns a D this week, moving down from last week’s grade of C. World Fuel Services Corporation is engaged in the marketing and sale of marine, aviation and land fuel products and related services on a worldwide basis. The company also gets F’s in sales growth. For more information, get Portfolio Grader’s complete analysis of INT stock.

ConocoPhillips (COP) experiences a ratings drop this week, going from last week’s D to a F. ConocoPhillips is an international company involved in the exploration, production, refining, and marketing of energy. The company also gets F’s in sales growth, operating margin growth, earnings revisions, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of COP stock.

This week, Western Gas Equity Partners LP’s (WGP) rating worsens to a F from the company’s D rating a week ago. The company also gets F’s in operating margin growth, earnings growth, and earnings surprise. For more information, get Portfolio Grader’s complete analysis of WGP stock.

This is a rough week for BP Prudhoe Bay Royalty Trust (BPT). The company’s rating falls to F from the previous week’s D. BP Prudhoe Bay Royalty Trust holds overriding royalty interests constituting a non-operational interest in minerals in the Prudhoe Bay oil field located on the North Slope in Alaska. The company also gets F’s in sales growth. For more information, get Portfolio Grader’s complete analysis of BPT stock.

Williams Partners, L.P.’s (WPZ) rating weakens this week, dropping to a F versus last week’s D. Williams Partners, L.P. is engaged in the business of gathering, transporting, processing and treating natural gas, as well as fractionating and storing natural gas liquids. The company also gets F’s in earnings growth, earnings surprise, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of WPZ stock.

Cheniere Energy Partners LP Holdings, LLC (CQH) is having a tough week. The company’s rating falls from a C to a D. For more information, get Portfolio Grader’s complete analysis of CQH stock.

Green Plains Inc. (GPRE) declines this week from a D to a F. Green Plains Inc. constructs and operates dry mill, fuel-grade ethanol production facilities. The company also gets F’s in operating margin growth, earnings growth, earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of GPRE stock.

Slipping from a D to a F rating, Whiting Petroleum Corporation (WLL) takes a hit this week. Whiting Petroleum Corporation acquires, exploits, develops and explores for crude oil, natural gas and natural gas liquids. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of WLL stock.

This week, NGL Energy Partners LP (NGL) drops from a D to a F rating. NGL Energy Partners LP owns and operates a vertically-integrated propane business. The company also gets F’s in sales growth, earnings revisions, earnings surprise, and free cash flow. For more information, get Portfolio Grader’s complete analysis of NGL stock.

Ring Energy, Inc. (REI) slips from a D to a F this week. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of REI stock.

Northern Oil and Gas, Inc. (NOG) earns a D this week, moving down from last week’s grade of C. Northern Oil and Gas, Inc. is an independent energy company that acquires, explores, exploits and develops oil and natural gas properties. The company also gets F’s in sales growth, operating margin growth, earnings growth, earnings revisions, earnings momentum, and free cash flow. For more information, get Portfolio Grader’s complete analysis of NOG stock.

TOP Ships Inc. (TOPS) experiences a ratings drop this week, going from last week’s D to a F. TOP Ships Inc. offers marine shipping services. The company also gets F’s in sales growth and free cash flow. For more information, get Portfolio Grader’s complete analysis of TOPS stock.

Memorial Production Partners LP (MEMP) slips from a D to a F this week. Memorial Production Partners LP engages in the acquisition, development, exploitation, and production of oil and natural gas properties. The company also gets F’s in sales growth, earnings growth, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of MEMP stock.

Azure Midstream Partners LP (AZUR) gets weaker ratings this week as last week’s D drops to a F. The company also gets F’s in earnings revisions, earnings momentum, return on equity, and free cash flow. For more information, get Portfolio Grader’s complete analysis of AZUR stock.

This week, Amyris, Inc. (AMRS) drops from a D to a F rating. Amyris, Inc. provides alternatives to a range of petroleum-sourced products used in specialty chemical and transportation fuel markets worldwide. The company also gets F’s in sales growth and free cash flow. For more information, get Portfolio Grader’s complete analysis of AMRS 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.