基于物理意义的示功图凡尔开闭点精确提取

Accurate extraction of valve opening and closing points based on the physical meaning of surface dynamometer card

凡尔开、闭点的提取是抽油井示功图识别与量化分析的基础,对抽油井故障诊断、功图量油等具有重要作用。根据有杆抽油泵的工作原理和凡尔开、闭点的物理意义,对地面示功图上凡尔开、闭点位置进行了理论分析,提出了一种精确提取地面示功图上凡尔开、闭点的方法。在位移-时间曲线上确定上、下死点后,对载荷-时间曲线进行分区、去噪(平滑去噪、拟合去噪、迭代去噪)后,直接采用穷举比较法寻找最优解,从而确定固定凡尔和游动凡尔打开点(B点、D点);采用相同方法再确定游动凡尔和固定凡尔的关闭点(A点、C点)。编制了相应的软件,并利用1 000多个算例进行验证(包括多种故障算例),结果表明该方法能精确确定示功图上凡尔开、闭点位置。

The extraction of valve opening and closing points is the basis for the identification and quantitative analysis of pumping well dynamometer cards,and it is important for the failure diagnosis and production evaluation of pumping wells.In light of the working principle of sucker rod pump and the physical meaning of surface dynamometer card,this paper discusses theoretically valve opening and closing points and presents an accurate method of extracting the valve opening and closing points of surface dynamometer cards.After the top and bottom dead centers are determined on displacement-time curve and the loading history curve is dealt with by parition and de-noising（smooth de-noisng,curve fitting and iteration de-noising）,methods of exhaustion and comparison are applied to find optimal solutions and to determine the opening points of travel valve and set valve.The opening points of the valves are determined by the same method.A corresponding computer program is developed and analyses of 1 000 examples indicate that this approach is effective.