Paper: F. Yavuz, J. Lea, P. Adisoemarta, T. Oetama and J.C. Cox, Texas Tech University

Fluid pound is thought to be a result of the pump hitting the fluid level when the pump is partially full of gas. However gas always is compressed to a value of pressure sufficient to open the traveling valve before the pump hits the fluid. The load on the pump is released very quickly and the pump is traveling faster when fluid pound occurs than at the beginning of the stroke. However, most down hole dynamometer cards do not show compression when fluid pound occurs. Also, the concept that there is fluid pound with gas in the pump at low pressures and gas interference when the pressure seems to be accepted. A model and all formulas for fluid pound and gas interference is presented and programmed into a short wave equation program. All code and formulas are shown. Results of high and low intake pressures on pumping with incomplete fillage are shown on the bottomhole dynamometer card and on the rod string loading. Also, effects of pumping speed and degree of pump fillage are shown on the dynamometer cards and the rod string loading. Conclusions on what effects fluid pound has on the pump system are presented, some of which conflict to some degree with traditional concepts.