The Fault Diagnosis System Of Sucker-rod Pumping Wells Based On Analysis Of Pumping Card

The sucker-rod pumping is the most widely used oil pumping equipment at home and abroad. It has many advantages, such as simple structure, easy to manufacture, convenient maintenance etc. Since the circumstance underground is very complicated and harsh, the sucker-rod pumping is often subjected to damage, especially the underground equipments, which would influences the production of oil field negatively and causes huge losses in economy if these faults fail to be treated in time. Therefore, the significance of fault diagnosis of sucker-rod pumping can never be exaggerated.Traditionally, people use (surface)indicator card to analyze the working condition of pump. However, there is a large discrepancy between indicator card and underground indicator card (pumping card) because of the vibration of sucker-rod and influences of other factors. As a result, it is considerably hard to analyze the working condition of pump just by using indicator card. This paper presents a method for judging the faults of sucker-rod pumping by analyzing pumping card. Firstly, converting the indicator card into pumping card; secondly, the expert system is introduced to analyze the working condition of equipments and finally draws the conclusion. Main tasks in this paper are as follows:(1) This paper introduces the leading methods and development of fault diagnosis, briefly analyzes the working principle of sucker-rod pumping and presents the main structure of diagnosis system.(2) The cause of formation of indicator card and relevant conceptions are put forward. Also this paper introduces the process of working out pumping card by using Gibbs wave equation. The main idea of this method is to regard the entire system as a vibration system, in which one end is free, and another end is forced to do reciprocating motion. This system has certain initial conditions and boundary conditions, and gives output (pumping card) in response to external excitation (indicator card).(3) This paper introduces expert system and relevant conceptions, and then builds up the knowledge base and inference engine, including the mathematic description of faults and corresponding inference rules. (4) The fault diagnosis system has been realized with the combine programming of VC++ and MATLAB. This system has following functions:calculating pumping card, displaying pumping card, fault diagnosis, giving the alarm and data management.The testing proves that this system can be realized easily and identify faults effectively. Therefore, this system can meet the demand of oil production.