Use of Advanced Pattern-Recognition and Knowledge-Based System in Analyzing Dynamometer Cards

Abstract

Summary A quick and accurate identification of downhole problems is essential in rod-pumping in order to minimize operating costs and to maximize oil production. TOTAL-CFP has developed, for its french subsidiary, a system to assist the engineers in the day-to-day oil field operations in rod pumping. The system will make rod-pumping expertise available to field-operations personnel. It provides a tool for improving data analysis and it can be used as a training aid for engineers dealing with rod-pumping wells for the first time. This system is made up of three sub-systems: a dynamogram acquisition system, a dynamogram management system and a knowledge-based system. This paper presents the knowledge-based system which is used for diagnosing downhole problems and suggesting corrective actions. To achieve these goals, the system applies advanced pattern recognition techniques which mainly consists of pattern recognition techniques which mainly consists of structural pattern recognition methods and hierarchical data structures, called Quadtrees. The diagnostics and recommendations are based on the analysis of surface dynamometer and downhole cards. The interface between the user and the system is very friendly. The system provides the user with graphical explanations of its diagnostics. A first version of the system (a prototype) was installed in March, 1991 and the specifications of the final version are planned for the end of the year. planned for the end of the year. Introduction In rod-pumping, apart from the normal decline of oil fields, the production decrease may have different origins. In this paper, production decrease may have different origins. In this paper, we mainly focus on the late downhole problems detection which can involve excessive repairs and maintenance, energy consumptions, etc… To detect and diagnose the downhole problems in rod-pumping, a knowledge-based system has been developed which mainly uses the surface dynamometer cards and the downhole cards. A surface dynamometer card is a record of the load vs. position of the polished rods. Because of the rod stretch, the surface dynamometer card cannot generally be used to understand how the pump is operating downhole. An analytical method allows to transform the load vs. position at the surface unit to load vs. position at the pump. This plot is called downhole card.