论文部分内容阅读
本文分析了简化模型下声波测井时裸眼井(内充流体一般是泥浆)中弹性波的传播,此波场可看成是轴向传播有不同波矢的分波的叠加。分析表明,对于井外只有单一均匀岩层且无限深的井,仅对如(18)式所示的特征频率成分才存在具有轴向传播最大相速度v_(zm)=c_2的所谓“首波”;而v_x>c_2及c_2>v_z>b_2的分波却不存在,此处c_2和b_2分别是井外岩层的纵波和横波速度。这正解释了文献[3]中所报道的裸眼井的“过滤效应”。分析还表明,对于井外具有多层岩层的井,只在一定条件下才存在与上述特性相近的“首波”。本文结果对声速测井显然是重要的。
In this paper, we analyze the propagation of elastic wave in the open-hole well (filled fluid generally is mud) under sonic logging in the simplified model. This wave field can be regarded as the superposition of the partial waves propagating with different wave vectors in the axial direction. The analysis shows that there is only the so-called “first wave” with the maximum axial velocity v_ (zm) = c_2 for the characteristic frequency components as shown in (18) for wells with only a single uniform formation and infinite depth. ; While the subsignals of v_x> c_2 and c_2> v_z> b_2 do not exist, where c_2 and b_2 are the longitudinal and shear wave velocities of the out-of-well rock formation, respectively. This explains the “filtration effect” of open-hole wells reported in [3]. The analysis also shows that for wells with multiple formations outside the well, there is a “first wave” similar to the above characteristics only under certain conditions. The results of this paper are obviously important for acoustic velocity logging.