钻头振动波井眼防碰监测系统及其现场试验

现有的井眼防碰检测技术均建立在井眼测量轨迹数据和钻进中对异常现象判断的基础上，由于各项数据误差及井下情况的不确定性，致使防碰作业存在极高的危险性。为此，根据现场实际防碰钻进时人工监听方法得到的启发，研发了钻头振动波井眼防碰监测系统：通过安装在套管顶端的加速度传感器采集井下沿套管传播的钻头破岩时产生的振动信号，并对信号进行特征提取以判断钻头趋近邻井套管的程度，利用计算分析软件实现信号特征显示，当信号特征值超过门限值时实现报警，由定向井工程师及时进行井眼防碰扫描，决定是否改变井眼轨迹。通过对比分析不同工况下监测系统采集振动信号的时域特点，认识到钻头钻速、钻压对钻头振动信号的影响，经过频域分析得到钻头振动信号的频域范围在200～400 Hz。该监测系统操作简单、不影响正常的油气井生产及钻井施工，目前已经在中国渤海、南海等区块进行了先导性试验，为井眼防碰技术发展提供了一条新的技术思路。

A drill bit vibration anti-collision monitoring system and field experiment

The present detection technique of borehole anti collision is generally based on the measured well trajectory data and the judgment on the abnormality in the drilling process. The error in data and the uncertainty of downhole situation will result in an extremely high risk in the downhole anti collision operation. Therefore, inspired by the human monitoring method at actual drilling sites, a drill bit vibration anti collision monitoring system was developed. First, the acceleration sensors installed at the top of the casing were used to collect the vibration signal of a drill bit; then, the feature signal was extracted to estimate the extent to which the drill bit was approaching the well casing; finally, the calculation analysis software was applied to manifest the characteristic signal: when the characteristic value exceeded the threshold value, an alarm was given for the directional drilling engineer to do the anti collision scanning immediately to decide whether or not to alter the well trajectory. Through analyzing the time domain signal collected by the monitoring system under different working conditions, we found the influence of drill speed and weight on bit; through analyzing the frequency domain signal, we determined the frequency range (200 400 Hz) as the drill bit signal. In those pilot tests performed in the well blocks in the Bohai Bay and South China Sea, the monitoring operation was proved to be simple and feasible with little effect on the normal production of oil wells and the drilling operation, providing a new way to the wellbore anti collision technology.