Heat olive oil in a large skillet over medium high heat. Add sausage, and cook, stirring frequently, until lightly browned, about 3 - 4 minutes.
Place sausage, garlic, onion, carrots, celery, beans, oregano and bay leaves into a 6 quart crockpot.
Stir in chicken broth and 2 cups water until well combined; season with salt and pepper to taste.
Cover and cook on LOW for 7 - 8 hours or HIGH for 3 - 4 hours. Stir in spinach until wilted.
Serve immediately.