基于示功图监测的煤粉相关井下故障预警

为了防治煤粉产出导致的煤层气井排水不畅、抽油泵漏失、卡泵等井下故障,进行了应用示功图预警煤粉产出对排采设备伤害程度的研究。基于鄂尔多斯盆地韩城地区煤层气生产实践,对煤粉相关井下故障的典型示功图进行了载荷分析与形状对比,提出了示功图监测预警煤粉相关井下故障的定量参数:卸载线滞后幅度R与载荷线偏差夹角θ。根据R与θ的变化范围,将相应井下故障强度划分为4个等级。排水不畅与卡泵生产实例的分析结果表明,示功图形状特征对煤粉聚集及其相关井下故障的严重程度具有指示预警作用。综合分析单井示功图形状及载荷比、变频器电流波动、日产水量变化等生产数据,可准确查明井下设备的功能状态与煤粉造成的伤害强度。对出现故障苗头的煤层气井及时采取回注排采与高效洗井等治理措施,可有效稀释煤粉浓度,扰乱煤粉聚集,加速煤粉运移,进而缓解煤粉伤害及相关井下故障。

Forecast of coal fines-related downhole failures based on monitoring dynamometer card

Coal fines generation can cause downhole failures during coalbed methane development,which include poor drainage,pump leakage and stuck pump.In order to prevent and control these failures,the research on the forecast of damage on production equipment caused by coal fines through monitoring dynamometer card was conducted.Based on the coalbed methane production in Hancheng,Ordos Basin,the load analysis and shape comparison of typical dynamometer cards of coal fines-related downhole failures were performed.Two quantitative parameters for indicating downhole failures by monitoring dynamometer card were proposed,which were R,unload line lag range and θ,load line deviation angle.According to the variation range of R and θ,the intensity of failures was divided into four grades respectively.The example analysis of poor drainage and stuck pump showed that the shape feature of dynamometer card could be indicative for the severity of coal fines aggregation and related downhole failures.The comprehensive analysis of the production data,such as the shape and load ratio of dynamometer card,the current fluctuation of inverter,and daily water yield change,can accurately identify the functional state of downhole equipment and the damage degree of coal fines.Adopting reinjection drainage,well washing and other control measures to the wells with failure symptom can effectively dilute coal fines concentration,disrupt coal fines aggregation,accelerate coal fines migration,and then mitigate coal fines damage and related downhole failures.