CHAPTER 7 

 SECOiNDARY RECOVERY OF PETROLEUM 



PAUL D. TORREY 



The following definition of secondary recovery by Johnson and van 

 Wingen ^ is used for the purpose of this paper : 



Recovery by any method (natural flow or artificial lift) of that petroleum 

 which enters a well as a result of augmentation of the remaining native reser- 

 voir energy (as by fluid injection) after a reservoir has approached its eco- 

 nomic production limit by primary recovery methods. 



It is appreciated that there is a growing tendency to include all water- 

 and gas-injection operations, regardless of the time during the life of a 

 reservoir in which they are commenced, within the scope of secondary 

 recovery. Some change in definition, therefore, may be adopted generally 

 in the future and, in fact, is recognized by certain authorities at present. 



From the foregoing definition it will be evident that there are three 

 fundamental requirements for the application of secondary methods: (1) 

 an injection well, (2) a producing well or wells drilled into, (3) a com- 

 mon porous and permeable oil-bearing formation, through which liquids 

 or gases are forced under artificial pressure. 



This paper considers the history of secondary-recovery operations in 

 the United States, the various methods that have been employed to increase 

 recovery from oil fields in which the primary reserve has become depleted, 

 secondary oil reserves in the United States, the susceptibility of oil fields 

 to the application of secondary methods, and the costs of development and 

 operation of secondary projects and some of the results that have been 

 obtained. A brief review of secondary operations in the Rocky Mountain 

 states is presented. 



The oil that may be produced by secondary methods does not require 

 discovery, and the application of these methods serves to make available 

 more of that which has already been found. For this reason, the additional 

 oil which is so obtained does not have to return exploration and leasing 

 expenses to yield a profit. The economic opportunities for secondary re- 

 covery, consequently, are sometimes more attractive than in the develop- 

 ment of primary production. However, for both primary and secondary 

 production, the amount of oil that can be obtained and the development 

 and operating expenses will determine the success or failure of a project. 

 Improvements in oil-recovery technology and increased prices for crude 

 oil are just as important in secondary operations as they are in primary 



' Johnson, Norris, and van Wingen, Nicco, Glossary of Terms and Definitions Pertaining to Second- 

 ary Recovery Operations, submitted to Standing Subcommittee on Secondary Recovery Methods, Am. 

 Petroleum Inst., Oct. 20, 1948. 



