Why is there so much crema on my espresso?
Crema is basically carbon dioxide fizzing up the coffee oils. By the description you're giving, it is likely to be too much. Your beans could be too oily and/or too fresh. It could be a combination of the type of beans / blend / or the way it's roasted. 

Just as a guide, it is best for the beans to rest for around about a week after it's roasted. And if your beans end up soaking in oil, that is not good!