Abstract
Oil recovery with pumping units is widely used in oilfield development at present. The management level of pumping units is related to the overall economic benefit of oilfield. In order to effectively control the production management of pumping wells, it is necessary to take all the production data to formulate a reasonable working system and make continuous analyses about the daily management level of pumping wells. The analysis and interpretation of the indicator diagram is a direct understanding way about the situation of deep well pumps in petroleum engineering. However, the complicated practical oilfield conditions often lead to the distortion of regular indicator diagrams, resulting in the low efficiency of fault-type diagnosis and wrong recognition. A new method of identifying the fault type of indicator diagrams is proposed by using the dynamic time warping (DTW) distance, through which a two-dimensional indicator diagram is transformed into a one-dimensional differential curve. The experimental results of real indicator diagrams show that the method is effective for the type diagnosis of indicator diagrams with high accuracy and fast speed.
Highlights
Rod pumping is the commonly used method for mechanical oil extraction
E actual indicator diagrams of pumping wells are the real reflection of the complex process of the deep pumping wells and the sucker rods. e curves in the indicator diagrams possibly fluctuate and change frequently, making the diagnosis result influenced by the subjective and objective factors such as the experiences and technical levels of the interpreter, so the efficiency and accuracy of the pumping system may be restricted to some extent [6, 7]
It can be inferred that if the difference between the up-stroke curve and the reverse-translational curve of the down stroke is transformed to a one-dimensional curve, which can be plotted through a differential curve, it will be much easier for interpreters to judge the fault type since the two-dimensional shapes of indicator diagrams have been expressed by one-dimensional differential curves. e differential curve is computed by the reverse-translational curve of the down stroke minus the up-stroke curve of the indicator diagram, through which the recognition of the fault type for pumping units is highly simplified
Summary
Rod pumping is the commonly used method for mechanical oil extraction. In order to understand the real underground working situation of the deep pumping wells, the indicator diagram records the real-time changes of curves related to the changes of states of light bars. A closed curve called an indicator diagram is drawn by a complete up-and-down stroke, which contains the rich information of the pump and the rod and their corresponding working situations. Indicator diagrams are viewed as one of the important basic sources in the fault diagnosis of pumping wells and the evaluation of oil production [1,2,3]. With the rapid development of computer sciences, many indicator diagrams and their corresponding types have been digitalized and defined in the database [8], which can be applied to the fault diagnosis in the real oilfields through the database. In this paper, based on the dynamic time warping (DTW) distance of time series [16], a new method for improving the identification of indicator diagrams is proposed. is method first uses the differential curves to convert the two-dimensional closed curves of the indicator diagrams into the one-dimensional curves and identify the type of indicator diagrams through the DTW distance [17, 18]. e experimental results show that our method can effectively distinguish similar curves of indicator diagrams, and the fault recognition for the unknown indicator diagrams is accurate and fast
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