Portal 2 GPU Analysis
Comparing Portal 2 PC system requirements to all GPUs shows that Portal 2 is going to need a graphics card that is capable of OpenGL 2.1.

Portal 2 makes use of DX 9.00 so a GPU with that capability could benefit from enhanced visuals.

To get the best visual graphical experience on Portal 2, aim to have a GPU that has at least 256MB GPU RAM.

Most bottom end graphics cards currently available today, will probably allow you to play Portal 2

We are advised that 14 year old graphics cards should be able to run Portal 2, but there could be a few exceptions to this rule.

Note that most games do not officially support laptop graphics cards, but nowadays many laptop graphics solutions are capable of running modern games. Whether desktop graphics cards or laptop, try searching for your graphics card to compare against the Portal 2 graphics card requirements chart below.