1. Heat the oil in a large pot over medium-high heat. Add the onion, celery, bell pepper, and garlic. Cook, stirring occasionally, until the vegetables are softened and lightly browned, about 5 minutes.
2. Stir in the rice, thyme, oregano, paprika, and cayenne pepper. Cook, stirring, for 1 minute.
3. Pour in the chicken broth and diced tomatoes. Bring to a boil, then reduce the heat to low. Cover and simmer until the rice is tender, about 15 minutes.
4. Stir in the smoked sausage and shrimp. Cook, stirring occasionally, until the shrimp is cooked through, about 5 minutes.
5. Serve hot.