1 6 NEW YORK STATE MUSEUM 



is probably as much as 80 per cent. In other words, not over 20 

 per cent of the total amount of oil contained in the sands is recover- 

 able by methods heretofore in common use. 



In order to recover part of the oil that is left in the sand when the 

 wells can no longer be profitably operated by the old method of 

 pumping, another method is being introduced for increasing the 

 production of oil wells, known as restored pressure or " flooding." 

 This method is not successful in all oil fields, but the oil sands of 

 New York and northern Pennsylvania lend themselves more 

 successfully to extraction of oil by flooding than any other known 

 oil pools. 



Briefly the method of obtaining oil through restored pressure is 

 as follows : 



Water is introduced into a well and by reason of the hydrostatic 

 pressure thus established by the water, the oil is forced away in 

 advance of the slowly moving water from the bottom of the well, 

 thus creating an oil flood. Wells are drilled in advance of the oil 

 flood which continue to produce until they are reached by the water 

 flood, after which, unless they are subjected to cross and reversed 

 flooding, they function only as pressure wells forcing the oil beyond 

 into an ever increasing area where new wells are drilled to obtain 

 the flood oil. 



This new method of obtaining oil by restored pressure is not with- 

 out its problems, for flooding is a new business venture and probably 

 less than 5 per cent of the New York fields have been subjected 

 to this process of extracting oil. Floods travel slowly, depending 

 mainly on the pressure applied and the porosity of the oil sands. 

 The average progress of a flood varies from 50 to 200 feet a year. 

 Although gratifying results have been obtained from the areas 

 already flooded there are grave dangers of costly mistakes 

 unless scientific studies are made of the best methods of 

 applying the flood. Such studies should include the spacing of 

 the wells, because there are many factors which determine the proper 

 number of wells in a given area. It is evident that the operator 

 desires to obtain the maximum amount of recoverable oil with the 

 fewest number of wells possible. At present the number of wells 

 an acre in flooded territory varies from two or three to as many as 

 ten in exceptional areas. The proper number of wells to drill on 

 various leases will of course vary with local conditions. These 

 local conditions will involve a study of well logs, dips, domes, 

 anticlines and other clinal structures, the depth of wells, thickness 

 of sands, rate of movement, direction and control of floods, pressure 



