This week, five energy services stocks are improving their overall rating on Portfolio Grader. Each of these rates an “A” (“strong buy”) or “B” overall (“buy”).

Synthesis Energy Systems, Inc. (SYMX) ups its rating to a B (“buy”) this week after earning a C (“hold”) in the week before. Synthesis Energy Systems designs, invests in, builds, owns, and operates utility plants for industrial customers. In Portfolio Grader’s specific subcategory of Sales Growth, SYMX also gets an A. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of SYMX stock.

Exterran Partners, L.P. (EXLP) is seeing ratings go up from a C last week to a B this week. Exterran Partners offers natural gas compression services. The stock has a dividend yield of 2.1%. For more information, get Portfolio Grader’s complete analysis of EXLP stock.

Parker Drilling Company (PKD) shows solid improvement this week. The company’s rating rises from a C to a B. Parker Drilling provides contract drilling and related services. The stock price has been on the rise for the past three days, reaching $7.71. Shares of the stock have been trading at an exceptionally rapid pace, up twofold from the week prior. For more information, get Portfolio Grader’s complete analysis of PKD stock.

This week, CARBO Ceramics’ (CRR) ratings are up from a C last week to a B. CARBO Ceramics manufactures and supplies resin-coated ceramic and resin-coated sand proppants primarily used in the hydraulic fracturing of natural gas and oil wells in the United States and internationally. The stock price has risen 12.2% over the past month, better than the 1.7% decrease the S&P 500 has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of CRR stock.

This is a strong week for Helmerich & Payne, Inc. (HP). The company’s rating climbs to B from the previous week’s C. Helmerich & Payne provides contract drilling of oil and gas wells in the Gulf of Mexico and South America. After five consecutive days of gains, the stock price has reached $96.27. The current dividend yield is 2.5%. For more information, get Portfolio Grader’s complete analysis of HP 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.