机械式井下震源设计及试验研究

Design and Experimental Study of Mechanical Downhole Seismic Source

针对钻头产生的振动波信号强度低,以及在地层和套管中传播时的衰减难以在深部地层进行防碰监测的问题,研制了一种机械式井下震源。该震源由储能-打击机构、控制机构和辅助机构等3部分组成。通过采集震源所产生的震动信号,可以识别钻头距风险邻井套管间的距离。震源主要以弹簧作为储能部件,操作套筒带动止推环运动,从而使弧形卡相对位置发生变化来控制弹簧的压缩及释放,通过与弹簧相连的冲击锤撞击铁砧产生打击。井下震源室内试验结果表明,其结构设计合理,功能易于实现,起震所产生的冲击力大小合适,符合设计要求,能够为防碰监测提供一定强度的标志性震动信号。

The low intensity of vibrating wave signals produced by drilling bit and their transmission attenuation in formation and casing prevent them from conducting anti-collision monitoring in deep formation. Therefore, a kind of mechanical downhole seismic source and vibration initiation mode was developed. The source consists of energy storage-impact mechanism, control mechanism and auxiliary mechanism. The vibration signals are collected from the source in order to identify the distance between drilling bit and risky neighboring well casing. The mechanical downhole source developed mainly takes spring as the energy-saving part. The operating sleeve is used to make anti- thrust ring move so as to make the relative position of arc clinch change to control the compression and release of spring. The spring and the impact hammer connected with it collide with strike anvil to produce impact. The labora- tory experimental findings of downhole source show that its structure is reasonable and its function is easy to a- chieve. The impact force produced by vibration initiation is suitable in agreement with the design requirement. It can offer characteristic vibrating signals of some intensity for anti-collision monitoring.