OCR Text |
Show Secondary Oil Recovery V v j ( Two-thirds of all U.S. oil deposits discovered are still in the ground because underground pressure diminished before the oil supply did. Now, like toothpaste at the bottom of a tube, it needs encouragement to emerge. This diagram depicts one of fifteen waterflood units operated by W. R. Grace & Co. in the western part of the country which artificially restores pressure by pumping pump-ing water into the fringes of the oil zone to force the crude to the surface without changing the environment. |