CHAPTER XII 



PHYSICAL PRINCIPLES APPLIED TO 

 PRODUCTION PROBLEMS 



The present chapter deals with the application of sound or pressure 

 waves for determining the distance (depth) to the fluid level and to partial 

 obstructions in an oil well. Before considering this specific application, it 

 is well to review briefly certain physical principles of oil recovery in wells. 



Principles Underlying Oil Recovery in Wells 



The fluid level in an oil well or, more specifically, the height to which 

 liquid petroleum and/or water stands above the producing horizon, is a 

 direct indication of the pressure exerted against the producing zone in the 

 bore-hole.f 



Under equilibrium conditions, 



where 



pbh = hd + Pg + p,n (1) 



Pbh= bottom hole pressure in pounds per sq. in. 



h = height of fluid in the well in ft. 



d = average fluid pressure gradient or fluid density in pounds 



per sq. in. per foot 

 pg = weight in pounds of section of gas column one inch square 



from fluid level to casing head 

 pgJ^ = casing head pressure in pounds per sq. in. 



In words, Equation 1 states that the bottom-hole pressure is equal to the 

 pressure of the column of fluid, plus the pressure of the gas column, plus the 

 casing-head pressure. 



t T. E. Swigert and C. R. Bopp, "Experiments in Use of Back-Pressure on Oil Wells," 

 U. S. Bureau of Mines, Tech. Paper 322, 1924. 



S. F. Shaw, "Well Back-Pressure and Fluid Levels," Oil and Gas Journal, Nov. 22, 1928. 



S. F. Shaw, "Increasing the Ultimate Recovery of Oil," A.I.M.E. Petroleum Technology, 

 1931, pp. 178-193. 



C. V. Millikan and Carrol V. Sidwell, "Bottom Hole Pressures in Oil Wells," A.I.M.E. 

 Petroleum Technology, 1931, pp. 194-205. 



C. V. Millikan, "Reservoir and Bottom Hole Producing Pressures as a Basis for the Pro- 

 ration of Crude Oil," Oil and Gas Journal, Aug. 11, 1933. 



C. E. Reistle, Jr., and E. P. Hayes, "A Study of Sub-Surface Pressures and Temperatures 

 in Flowing Wells in the East Texas Field and the Application of These Data to Reservoir and 

 Vertical Flow Problems," U. S. Bur. of Mines Report of Investigations, 3211, May 1933. 



H. C. Miller, E. S. Burnett, and R. V. Higgins, "Oil Well Behavior Based upon Sub- 

 surface Pressures and Production Data," A.I.M.E. Petroleum Technology, 1937, pp. 97-109. 



M. Muskat, "Use of Data on the Build-up of Bottom Hole Pressures," A.I.M.E. Petroleum 

 Technology, 1937, pp. 44-48. 



M. Muskat, R. D. Wyckoff, H. G. Botset, and M. W. Meres, "Flow of Gas Liquid Mixtures 

 Through Sands," A.I.M.E. Petroleum Technology, 1937, pp. 69-96. 



M. L. Haider, "The Productivity Index," A.I.M.E. Petroleum Technology. 1937, pp. 112-119. 



J. J. Jakosky, "Bottom Hole Measurements in Pumping Wells," A.I.M.E. Petroleum Tech- 

 nology, Tech. Pub. 1058, 1939. 



