For the 11th straight year, Platts ranked 250 of the world's top energy companies. Not surprisingly, the top 10 are all oil and gas companies. The list highlights some important trends for investors, however, and is worth considering in that respect.

The list
Platts evaluated the world's energy companies using four metrics: asset value, revenue, profit, and return on invested capital. The top 10 are listed here:

Rank

Company Name

2011 Rank

1

ExxonMobil (XOM 0.23%)

1

2

Royal Dutch Shell (RDS.A)

6

3

Chevron (NYSE: CVX)

2

4

BP (BP 0.71%)

118

5

Gazprom

3

6

Statoil (EQNR 2.77%)

11

7

Total (NYSE: TOT)

5

8

ConocoPhillips (NYSE: COP)

7

9

PetroChina (PTR)

4

10

Rosneft

9

Source: Platts.

Though ExxonMobil ranked first for the eighth straight year, there is a fair bit of movement on this list compared to last year's -- most notably, BP's rise from 37th place to fourth. It was the biggest mover on the list this year. BP plummeted in the 2011 rankings as it dealt with financial repercussions from its Gulf of Mexico disaster. Royal Dutch Shell and Statoil also jumped several spots this year, as the integrated majors continue to dominate the top 10.

Trends
Though PetroChina dropped five spots, China's overall presence on the list surged this year. The nation had 23 companies on the list, more than any other individual country other than the United States. Twenty of those companies also appeared on Platts' 50 Fastest Growing list, compiled from three-year compound growth rates.

Overall, Asia-based companies are slowly improving their positions on the Platts list. Seventy Asian companies were ranked this year, just as they were last year, but there were 12 in the top 50, an improvement over only nine companies in 2011.

More significantly, the companies on this year's list go beyond the PetroChinas and the CNOOCs that one would expect, to include other energy sectors, like coal and electric utilities. In fact, five of China's eight companies on the 50 Fastest Growing list are independent power producers.

Foolish takeaway
List are everywhere these days, and when they come from reputable sources like Platts, or trade magazines and industry journals, they often provide a great beginning for investment research. Keep tabs on the best of the best -- click here to add the companies above to My Watchlist.