Abstract:

Prediction for down-hole working conditions of beam pumping units is an effective strategy to timely control oil well's working state, and is important to improve production efficiency and to reduce maintenance cost.Chaos theory was used in transient prediction for oil well's down-hole working conditions.First, moment eigenvalues of invariant curves were extracted from dynamometer chart as predictive variables.Then, after data sequence of these predictive variables were proved to have chaotic characteristics, chaotic time series prediction model was established by ELM(kernel extreme learning machine) method and several uncertain variables of the model were optimally solved by IFOA(improved fruit fly optimization algorithm) with two strategies of global population diversity-evolution and local individual random-variation.Finally, model predictive results were analyzed to determine fault types according to MEA(matter-element analysis) method.Case study of two oil wells in one oilfield showed that the IFOA-KELM-MEA prediction model was reasonable and effective.

Key words: chaotic time series prediction, beam pumping units, kernel extreme learning machine, fruit fly optimization algorithm, matter-element analysis, measurement, petroleum, model

摘要：

实现对井下工况的预测是及时掌握抽油井生产状态的有效方法，对提高油井生产效率和降低维护成本具有十分重要的意义。采用混沌理论实现抽油井井下工况的短期预测，首先将所提取的示功图的不变曲线矩特征向量作为预测变量，在证明其数据序列具有混沌特性后，由核极限学习机（kernel extreme learning machine，ELM）建立混沌时间序列预测模型，对其中的几个不确定参数采用改进的果蝇优化算法（improved fruit fly optimizationalgorithm，IFOA）进行优化选取，IFOA采用全局群体多样进化和局部个体随机变异的策略，最后，对模型所预测的结果进行物元分析（matter-element analysis，MEA），诊断其属于哪种故障类型。由某油田作业区的两口生产井进行实例验证，结果表明所提出的IFOA-KELM-MEA预测模型是合理有效的。

关键词: 混沌时间序列预测, 游梁式抽油机, 核极限学习机, 果蝇优化算法, 物元分析, 测量, 石油, 模型