Hi Craig,
I've cleaned really dirty greasy/oily carpet areas around the kitchen area in pubs and restaurants and have found prochems power burst pre-spray very effective especially if its given 5-10 minutes dwell time then agitated thoroughly. I then extract with fibre and fabric rinse to neutralise.

Picture of Indian restaurant carpet part done with power burst and fibre and fabric rinse and using a 135psi portable! This carpet was filthy and my shoes stuck to it if I stayed still long enough!
I would try this method perhaps more than once if needed then remove stubborn spots with solvall spotter. I would imagine it's carpet tiles or a very short pile commercial carpet if its in an office so shouldn't be that bad. Just be careful if the tiles are bitumen backed as solvent spotters can draw the bitumen through to the surface and make matters worse. If they are carpet tiles and are bitumen backed try citrus gel instead.
Kind regards,
Jason.