Peter Thomas Roth makes an excellent gel formula that you rub on your face and it gives instant mattifying results and it keeps working for hours. It is called "Anti-Shine Mattifying Gel". If it doesn't keep you completely matte throughout the day I would recommend using Urban Decay's "De-Slick Mattifying Powder" which is colorless and does a great job of absorbing oil.
I hope this helps you . . .
coming from someone who battles with oily skin all the time I really don't think there's a way to prevent oil from shining through for the entire day. For someone like you who doesn't even wear makeup blotting papers are a great solution! You can try cheaper rice papers with rice powder that soak up the oil.
However, they do make a range of products that attempt to mattify your skin.
I've tried Urban Decay's De-Slick in a Tube and Murad's Oil-Control Mattifier and I do like to use a primer as well which is supposed to minimize oil even if you don't use it as a base for makeup.
There's also Clinique's Pore Minimizer T-Zone Shine Control which minimizes the appearance of pores and controls the oil on your face. But I'm afraid none of these products will prevent a shiny face for 12+ hours, probably not even 6+ hours.