声电效应测井电声比及其与地层渗透率的关系

The ratio of the acoustoelectric field to the acoustic pressure in a borehole and its dependence on permeability

基于流体饱和孔隙介质中声波-电磁场耦合效应的测井方法具有潜在的应用价值.本文从Pride动电耦合波方程组入手,推导了伴随斯通利波的井孔电场与声压比值(电声比)的频率域表达式.结果表明,在较低频率条件下,电声比幅角的正切值与渗透率呈反比.在此基础上,提出了利用低频的声电效应测井全波反演地层渗透率的方法.针对砂岩地层,从计算模拟的声电效应测井响应反演出了渗透率,其值比利用声波测井斯通利波反演的渗透率更接近真实值.

Acoustoelectric logging based on the coupling between elastic wave and electromagnetic field in fluid-saturated porous media has potential value in the detection of formation characteristics. Applying Pridels equations for the coupled poroelastic and electromagnetic fields, we derive the expression of the ratio of the borehole acoustoelectric field accompanying the Stoneley wave to the acoustic pressure （REP） in the frequency domain. It is shown that the tangent of the REPrs argument is inversely proportional to permeability. On this basis, we propose a method to invert formation permeability from the full waveforms of the low-frequency acoustoelectric logging. Permeabilities of sandstones are estimated from the simulated acoustoelectric logs, and they are closer to the true values than those obtained by using the Stoneley wave of acoustic logging.