Heat oil and 2 cups of broth in a Dutch oven or 2 qt pan or larger, over medium-high heat. Add onions, celery, carrots, and sage and cook, stirring often, until soft, about 3 minutes. Stir in remaining broth and water, increase heat to high, cover, and bring to a boil. Add beans and chicken and cook, covered, stirring occasionally, for about 30-40 minutes. Serve hot.