Introduction

This chapter deals with the different calculation models that enable the determination of the most important operating parameters of sucker-rod pumping. The available calculation procedures will be presented in the order of their introduction, starting with the earliest and simplest formulae of limited accuracy and ending with the up-to-date complex simulation models. The accurate prediction of the operating conditions of a rod pumping system has a vital importance for the design of new installations and also for the analysis, as well as optimization, of existing installations. There are some very basic operational parameters, most of the additional data required for design or analysis can be derived from:

• the polished rod loads occurring during pumping

• the downhole stroke length of the plunger

• the torques required at the speed reducer

Due to the importance of the above parameters, several approximate formulae and calculation methods have been developed in the past to find their values. Of these, early procedures that give fairly good estimations for shallow wells when pumping light fluid loads are discussed in this chapter. Under such circumstances, the rod string can be treated as a concentrated mass, and this assumption leads to quite simple physical and mathematical models. As well depths increase, however, the assumptions of these conventional predictions are no longer valid, and the calculation accuracies attained rapidly deteriorate.

A detailed treatment of the API RP 11L procedure is presented, which ensures a much higher degree of accuracy in the calculation of pumping parameters than the simple formulae...