The most popular artificial lift system is traditionally the sucker rod pump and some 90 % of all the wells are equipped by such a pump. Even though the system is in place since decades, there are still arguments for research. A trend towards energy reduction and therefore to achieve a more efficient way of its usage has become the most important part of the overall expenses for sucker rod equipped pumped fields. The inefficient usage of energy is one of the biggest issues for achieving a low cost operation. In this thesis, a thorough technical investigation of the operation and performance of sucker rod pumps was realized. The optimized system is based on the behaviour of cyclic loading versus required power, production rate, a variable control speed and the amount of consumed energy. Through the development of mathematical models, sensors, controls, the use of data acquisition systems and two different types of variable frequency devices, the measured signals were analysed and a study based on system efficiency was performed. A method based on frequency-elastic operation using a converter was applied. A comparison between this proposed method and the use of a converter by fixed – frequency was realized. As result, through the better distribution of energy, the method based on the frequency-elastic operation led to approximately 16 % of peak power reduction (at a production rate of 4 strokes/minute). Moreover a proposal is presented considering a balanced pumping system and its behaviour in function of frequency-elastic operation mode and fixed-frequency operation mode. Two different induction machines (standard and NEMA D) were analysed and their losses were estimated according to both methods. As result, by using the elastic frequency method, losses reduction in the induction machine could be achieved at remarkable extent at the same production rate. The losses reduction for a standard machine was about 26.38 % and for a NEMA D machine about 23.94 %. Therefore, once the NEMA D machine was replaced by a standard machine and the proposed method was applied, the total losses reduction was about 45 %. Due to that a significant reduction of costs is also presented. Based on the achieved results, this thesis provides an overall understanding of the problem areas and delivers proposals in order to optimize the system from the energy efficiency point of view.
|Translated title of the contribution||Energie Optimierung von Sucker Rod Pumpen|
|Publication status||Published - 2014|