To accurately recognize the valve opening and closing points of dynamometer cards is of great significance to fault diagnosis and oil yield calculation about dynamometer cards from sucker-rod pumping wells. Aiming at the limitations of valve opening and closing points recognition research and the oil production characteristics in the context of big data, and further improving the recognition accuracy and practicality, a novel method based on 8-directions chain code and shape matching to identify the valve opening and closing points of surface dynamometer cards from sucker-rod pumping wells is proposed. Firstly, by analyzing the theoretical dynamometer card and the physical expression meaning of valve opening and closing points, the contour of the preprocessing surface dynamometer card was extracted by 8-direction chain code. Then the shape matching database was established, and the extracted contour was smoothed and the chain code was compressed in a certain number of iterations until the shape matches with the database shape data. Finally, the valve opening and closing points of surface dynamometer cards were located by the positioning rule of the matched shape. The proposed method was applied to the valve opening and closing points recognition of 1650 surface dynamometer cards in a block in Shengli Oilfield, and the located valve opening and closing points were applied to eleven kinds of the working condition recognition from sixty sucker-rod pumping wells. Compared with the working condition recognition methods based on the proposed method and based on the existing 4-direction chain code and polygonal approximation method, the working condition recognition rate is improved by about 1%. The result shows that the accurate valve opening and closing points recognition can improve the fault diagnosis rate and the liquid production capacity calculation accuracy rate by dynamometer cards, thus validates the effectiveness of this method.
周斌,邢林林,张敏. 基于八链码形状匹配的抽油机井地面示功图凡尔开闭点识别[J]. 科学技术与工程, 2022, 22(12): 4788-4796.
Zhou Bin, Xing Linlin, Zhang Min. Valve Opening and Closing Points Recognition in Surface Dynamometer Cards from Sucker-rod Pumping Wells Based on 8-direction Chain Code and Shape Matching[J]. Science Technology and Engineering,2022,22(12):4788-4796.