【摘要】 随钻地震(SWD)是利用钻头旋转破岩振动产生的地震波来实现钻前预测的一项新技术。因钻头振动能量弱、井场噪音能量强以及随机连续振动造成的不同时刻、不同震相的波相互叠加,使随钻地震信噪比很低,波场非常复杂,数据处理难度大。而现场试验周期长,费用高,地下结构等未知因素多,不利于开展SWD研究。数值模拟具有在控制条件下开展研究的优势,是一种高效、廉价的数值实验方法。在Seismod地震波场模拟软件和Matlab信号分析软件的基础上,针对随钻地震低信噪比、震源信号连续随机的特点,以黏弹性介质地震波动方程、交错网格高阶有限差分数值解法和互相关信号分析为核心,建立了SWD数值实验平台,算例结果证明该模拟平台是可靠的。同时利用该模拟平台对SWD波场传播、直达波与反射波时距曲线特征、数据处理方法等进行了数值实验,深化了对SWD波场传播规律和SWD数据处理方法的认识。更多还原

【Abstract】 Seismic While Drilling(SWD) is a new technology to predict the formation by analysing acoustic waves that are emitted from drill-bit.Due to the low energy of drill-bit vibration and the high energy of rig noise along with the superposition of different time and different wave,the SWD signal to noise ratio(S/N) is very low which makes the wave-field complex and difficult for processing.It is difficult to conduct SWD research due to the long experiment time,high expense and unknown underground geological structure.While numerical simulation is a high-efficiency and low-expense numerical experiment technique.Based on seismic wave-field simulation software Seismod and signal processing software using Matlab,a SWD simulation platform was created based on seismic elastic wave equations,the staggered grid high-level finite-difference numerical solution,and the signal processing method of the cross-correlation signal.The simulation results indicate that this numerical simulation platform is reliable.Using this platform,SWD wave-field propagation,the time-distance curve characteristics of direct wave and reflect wave,and data processing method were simulated which can help us understand the SWD propagation and data processing.更多还原