摘要
The seismoelectric effects induced from the coupling of the seismic wave field and the electromagnetic field depend on the physical properties of the reservoir rocks.We built an experimental apparatus to measure the seismoelectric effects in saturated sandstone samples.We recorded the seismoelectric signals induced by P-waves and studied the attenuation of the seismoelectric signals induced at the sandstone interface.The analysis of the seismoelectric effects suggests that the minimization of the potential difference between the reference potential and the baseline potential of the seismoelectric disturbance area is critical to the accuracy of the seismoelectric measurements and greatly improves the detectability of the seismoelectric signals.The experimental results confirmed that the seismoelectric coupling of the seismic wave field and the electromagnetic field is induced when seismic wave propagating in a fluid-saturated porous medium.The amplitudes of the seismoelectric signals decrease linearly with increasing distance between the source and the interface,and decay exponentially with increasing distance between the receiver and the interface.The seismoelectric response of sandstone samples with different permeabilities suggests that the seismoelectric response is directly related to permeability,which should help obtaining the permeability of reservoirs in the future.
地震波场和电磁场耦合产生的震电效应与储层物性参数有关,含流体孔隙介质中震电效应的研究有助于更好的描述储层特性。本文我们对饱和砂岩样品中的震电效应进行了实验研究,构建了一套震电测量装置。利用此测量装置记录了在声波激励下砂岩样品中产生的震电转换信号,观测得到了砂岩界面产生的震电信号的衰减特性,在此基础上进一步研究了震电信号与砂岩物理参数之间的关系。在震电效应的实验中发现尽量减小参考电位与震电信号扰动区的基准电位之间的电位差是保证震电实验测量精确性的关键点,能够显著提高震电信号的可探测性。震电测量结果证实了地震波在含流体孔隙介质中传播时,能诱导震电耦合,同时给出了震电界面响应的特点。震电信号振幅随着波源与岩样距离的增加呈线性衰减,随着接收电极与岩样界面距离的增加呈指数衰减。不同渗透率砂岩样品中产生的震电响应结果表明震电响应的强弱与样品渗透率成正相关,震电效应可以作为研究储层渗透率的一种新方法。
基金
supported by the National Science and Technology Major Project(No.2016ZX05018-005)
the New Methods,New Technology Research of Geophysical Prospecting(No.2014A-3612)
