Add the oil to a large pot and add in the celery, carrots, green onion, garlic and salt. Cook on medium heat for 5 minutes, stirring regularly. Add in the chicken and cook 5 more minutes. Add in the broth, green beans, rosemary, and thyme. Stir well, cover, reduce heat to medium/low and cook 25-30 minutes, stirring occasionally until veggies are tender.