Recent buy: Royal Dutch Shell

Last week I've purchased another batch of shares. It was finally time for me to pounce on the recent weakness in oil stocks. Currently I have three oil related stocks in my portfolio: Exxon Mobil, Kinder Morgan and Royal Dutch Shell. I decided to add 40 shares to my current position of Royal Dutch Shell for €20.50 per share. This is the lowest price I paid in all of my RDS purchases in 6 years.

My reasoning is as follows:

• Shell is a fundamentally sound company and also important: it's an integrated energy company. Lower oil prices are obviously bad for upstream business (exploration and production) but margins for downstream operations (refineries) are increasing.
• Management seems to be doing a good job with unloading assets at times with higher oil prices and buying back shares when prices are low. 
• Oil prices will fluctuate. They have so done in the past and will do so in the future. I still see future potential in the oil business (like for 20-30 years or so) before alternatives are economically feasible and provide enough (and stable!) energy. The world's population is growing to 9 billion people and these people need energy. Shell can and will provide these needs. 
• The dividend yield of 8% looks awesome! 
• I wanted to strengthen my EURO-denominated part of the portfolio. About 75% of my stock portfolio is listed in US dollars. I am not too uncomfortable with that right now, but it still provided me with an extra argument to purchase RDS.

I now own 150 shares of RDS. These new 40 shares add roughly €67 to my annual forward dividend income which now stands at €1.813.

What do you think of my purchase? And my reasoning?