PRODUCTION PROBLEMS 1125 



lower the instrument beyond certain critical rates of flow, which are a function of the 

 respective cross-sectional areas of the bomb and the tubing, the velocity of the rising 

 column, and the specific gravity of the fluid being produced. If bottom-hole pressures 

 are to be taken by the pressure-bomb method when a well is pumping, it is generally 

 most expedient to attach a clock-driven gauge to the bottom of the pump. In some 

 wells it is possible to lower a small diameter pressure gaugef on a wire line in the 

 annular space between the tubing and the casing. This method is subject to a number 

 of limitations such as the size of the annular space, or the presence of waxy deposits 

 or other obstructions such as liner tops, tubing catchers, or anchors. The attachment 

 of a gauge to the bottom of the pump necessitates removing the pump, the rods, and 

 at times even the tubing from the well. The equipment is then run back into the hole, 

 and the gauge records the pressure existing in the well at the depth of the pump. On 

 conclusion of a run, the pump must be pulled a second time to recover the gauge and 

 chart. The record shows the variations in pressure versus time during the test. 



It is evident that the above procedure for the procurement of direct bottom-hole 

 pressures in pumping wells entails considerable time and expense for pulling rods and 

 possibly tubing, as well as loss of production during the time the well is idle. Also, 

 the effects produced on the bottom-hole pressures by altering the pump speed or the 

 rate of production while the gauge is in the well are not available until after the instru- 

 ment is recovered. Experience with pumping wells has indicated that it is generally 

 most expedient to determine the height of the fluid column when the well is shut in, or 

 producing at various rates, and to translate the column weight into a corresponding 

 bottom hole pressure. Such tests can be made more economically and without shutting 

 down operations or pulling rods and tubing. 



METHODS FOR DETERMINING FLUID LEVELS 



Under certain conditions, various types of measuring lines, floats, and 

 chalk-line systems may be employed for determining fluid heights. As a 

 general rule, however, such methods are limited to open wells and cannot 

 be employed successfully during pumping operations. The most practical 

 methods for measuring fluid levels in pumping wells or wells under pressure 

 utilize sound or pressure wave reflections. 



Considerable work has been done on sound ranging,^ sonic means of 

 determining fluid levels, and also on sound or pressure-wave methods for 

 locating obstructions in tubings of various kinds. § The first practical 

 applications of the wave method in the United States were probably made 



t C. C. Olson, "Running Instruments in Annulus of Tubed Wells," The Oil Weekly, March 4, 

 1946. 



t C. W. Rice, "Sound Wave Apparatus," U. S. Patent 1,889,614, issued Nov. 29, 1932. 



R. A. Fessenden, "Method and Apparatus for Determining Distance by Echo," U. S. Patent 

 1,853,119, issued April 12, 1932. 



P. Langevin and C. L. Florisson, "Method and Apparatus for Sounding and for Locating 

 Submarine Obstacles by Means of Ultra-Audible Waves," U. S. Patent 1,858,931, issued 

 May 17, 1932. 



H. C. Hayes, "Method and Apparatus for Sound Ranging," U. S. Patent 1,900,015, issued 

 March 7, 1933. 



E. E. Turner, U. S. Patents 2,009,460, 2,003,160, 2,044,820, on echo methods of measuring 

 depths, issued July 30, 1935, Mar. 10, 1936, and June 23, 1936, respectively. 



R. L. Williams, "Method and Apparatus for Measuring Distances and Depths," U. S. Patent 

 2,015,702, issued Oct. 1, 1935. 



§ Th. Vautier, "Secondary Waves Produced by an Aerial Wave," Comptes Rendus, June, 

 1925, p. 1919; "Experimental Researches on Propagation of Aerial Waves Through a Long 

 Cylindrical Pipe"; Annates de Physique, Series 10, Vol. 6, pp. 311-364, 1926; Vol. 14, Annates de 

 Physique, pp. 263-626, 1930. 



