In a large, oven-safe skillet over medium heat, add olive oil and butter. Once the butter has melted, add onions, celery, and carrots. Cook until fragrant, 3-4 minutes. Add thyme, red pepper flakes, salt, and pepper. Add the wild rice and cook for 2-3 minutes. Pour 5 cups of water in with the rice and vegetables and bring to a boil. Cover and reduce the heat to low. Allow the wild rice mixture to cook covered for 45 minutes, or until the rice is tender.