Sprinkle the sugar into a small saucepan. Place the pan over medium-high heat and warm the sugar until it starts to melt and color. As soon as you see it turn brown, begin to gently swirl the pan. When the sugar has turned a deep caramel color (you can put a drop of sugar on a white plate to test the color), about 3 minutes, stand back and add the white wine and orange juice. It may bubble and spatter, so watch out. Turn the heat up to high, stir with a wooden spoon, and boil the sauce until it is reduced by half — you should have about 1/3 cup. Pull the pan from the heat and set it aside. (You can make the sauce up to 2 days ahead and keep it covered in the refrigerator.).
Pat the scallops dry between two paper towels. Slice or pull off the little muscle attached to the sides of the scallops. Have a warm serving platter and a small strainer at the ready.
Put the saucepan with the caramel sauce over very low heat so that it can warm while you cook the scallops.
Put a heavy-bottomed skillet over high heat. When the pan is hot, pour in 1 1/2 teaspoons olive oil and swirl to coat the bottom. Add the scallops, season them with salt and pepper, add a little more oil if needed, and cook for another 1 to 2 minutes, or until the scallops are firm on the outside and just barely opaque in the center — nick one to test. Transfer the scallops to the serving platter.
Check that the caramel sauce is hot — give it more heat if necessary. Pull the pan from the heat and toss in the butter, bit by bit, swirling the pan until the butter is melted and the sauce is glistening. Season the sauce with salt and pepper, then pour through the strainer into a sauceboat or pitcher. Drizzle some of the sauce over the scallops and pass the rest at the table.
Note: For even better flavour in the sauce (imo), use the juice of a Seville Orange if you can access.