贴井壁声波测井仪的有限差分模拟研究  

Finite difference modeling of the acoustic field by sidewall logging devices

作　　者：何峰江[1] 陶果[1] 王锡莉 

机构地区：[1]中国石油大学(北京)CNPC测井重点实验室,北京昌平102249 [2]新疆测井公司岩石物理研究中心,新疆克拉玛依834000

出　　处：《地球物理学报》2006年第3期923-928,共6页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(50374048)资助

摘　　要：贴井壁声波测井仪在石油勘探开发中具有广泛的应用.它能够避开泥浆的影响而直接检测井壁附近的地层性质.但目前对此进行的数值模拟研究还仅局限于比较简单的模型.有限差分法可以模拟比较复杂的井眼模型,然而贴井壁声源的频率较高(80kHz左右),使有限差分法计算量过大.本文应用局部加密交错网格有限差分方法解决了这类数值模拟中计算精度和计算量之间的矛盾.用这种算法模拟了井中有仪器时贴井壁声源激发的声场,并将其与无仪器时的声场作了比较.对模拟结果的验证和分析显示,该有限差分方法能够正确模拟贴井壁声源激发的声场.通过考察井中仪器本体对贴井壁声源激发声场的影响发现,测井仪器本体能够对直达波进行衰减而对环绕井壁传播的面波影响不大.Sidewall acoustic logging tools have been used in oil fields for directly characterizing formations nearby boreholes and evaluating the quality of the cementation in cased holes without significant interferences of drilling mud. However so far studies on the acoustic field by such a device are only limited to a few simple cases. In this paper, we investigate the 3-D acoustic field problem with finite difference modeling for more realistic cases containing the tool body itself. We have solved the problem by employing a FDTD method with a non-uniform staggered grid. Our results demonstrate that this method can simulate such an acoustic field accurately. By comparing beth the results with and without the considered tool body, we find that the existing of the logging tool body would substantially attenuate direct waves but has only little effects on interface waves.

关 键 词：井中声场模拟 贴井壁声波测井 局部加密交错网格 有限差分 

分 类 号：P631[天文地球—地质矿产勘探]