1. In a large pot, warm oil over medium heat. Add onion and celery and cook, stirring, until soft, about 5 minutes. Sprinkle flour over vegetables and sauté for 1 minute.
2. Stir in potatoes, clam juice, broth and 2 cups of water. Bring just to a boil, reduce heat to medium-low and cook until potatoes are tender, about 12 minutes.
3. Stir in half-and-half and shrimp and cook until heated through, about 5 minutes. Season with salt and pepper and serve hot.