AT present there are three methods of rejuvenating oilfields repressuring the oil-sands with gas, air or with water. This paper describes the latter method, which is known as the forced drive" or "water flooding system." There is only one place in the world where this method of rejuvenation is used on a large scale; that is, in the Bradford and Allegany field of north-western Pennsylvania and south-western New York. Flooding has been responsible for the complete revival of the Bradford field, which has been producing for sixty-two years. Out of a total of 85,000 acres, there remains 69,000 acres yet to be developed and produced by water flooding. This paper briefly traces the development of flooding since its beginning and describes present-day methods. A discussion of development costs, equipment used, and a brief summary of existing view-points concerning some of the technical phases of this type of rejuvenation is given. Although recoveries from flooding operations have been small, compared with the recoveries obtained from natural production in other producing districts of the world, they are sufficient, nevertheless, to make flooding operations profitable. In the old, natural floods where hydrostatic pressure alone was used, the average recovery was approximately 3960 barrels per acre. Present-day flooding involving the use of pump pressure to augment hydrostatic pressure gives recoveries of approximately 6000 barrels per acre on leases with which the writer is familiar. The average flood well produces about 16 barrels per day at its peak. -Peak production is generally reached four and onehalf months after the beginning of a flood, and the average well has a total life of approximately thirty and one-half months. Wells closely spaced yield higher peak productions than widely spaced wells for any gives pressure, and their productive life is shorter. Wider spaced wells, however, may be given the characteristics of closely spaced wells by means of increased pressure applied at the water intake wells. There are two schools of thought concerning the shape of the flood zone between wells, and these points are briefly discussed in the paper. It is the writer's opinion that eventually flooding will be found successful and economically practicable in the rejuvenation of other old oilfields, providing plentiful supplies of satisfactory water for flooding are available, and the producing sand is not too variable in permeability.
. Up to the present time petroleum technology has developed for use three artificial methods for the rejuvenation of oilfields. These are: repressuring the oil-sand with gas, air or with water, the latter being known as the "forced drive" or "water flooding" system.