Preheat an oven to 350 degrees F (175 degrees C). Spray a 9x13 inch baking dish with nonstick cooking spray.
Heat olive oil in a large skillet over medium heat. Cook the onion in the oil until translucent, about 5 minutes. Stir in the ground buffalo. Cook, breaking up meat with a spoon as it browns, about 10 minutes. Sprinkle the contents of 1 taco seasoning packet over meat and onion; mix well.
Combine the remaining packet of taco seasoning mix and the refried beans in a small bowl. Spread seasoned beans in the prepared baking dish. Layer the buffalo and onion mixture, guacamole, and sour cream over the beans. Top with the black olives, green onions, jalapenos, and the shredded Cheddar cheese.
Bake in the preheated oven until the cheese is melted, and the ingredients are hot, about 30 minutes.