Heat olive oil in a large cast iron 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-qt slow cooker; season with salt and pepper, to taste.
Stir in chicken broth and 2 cups water. Cover and cook on low heat for 7-8 hours or high heat for 3-4 hours.