Two small scale acoustic phased arrays with 4 elements have been designed and assembled in the laboratory. Experiments have been carried out with them. It is found that both directivity and radiation lobe width of the phased array can be regulated by changing the time delay between the input signals on neighboring elements. Results measured are in goon agreement with those calculated. By using the phased array as an acoustic transmitter and hydrophone as a receiver, small scale acoustic well-logging simulations have been carried out both on an aluminum model well and on a concrete one. Experimental results show that, by increasing the time delay of the input signals on neighboring elements, the steered radiation angle of the phased array becomes larger and larger, and generation conditions of the refracted compressional wave and the refracted shear wave are reached successively, and the refracted compressional wave, the refracted shear wave and the Stoneley wave are strengthened, respectively. Therefore, by choosing element spacing of a phased array and acoustic wave frequency appropriately, the main radiation lobe of the phased array can be widened to cover the first critical angle of all kinds of formations, which makes it possible to apply phased array acoustic well-logging in any formation continuously without regulating directivity of the phased array.

应用有限元法研究了充液井孔中的相控线阵声波辐射器在井外地层中产生的声场,探讨了增强声源向地层的某一特定方向辐射的声波能量的方法. 采用相控线阵声波辐射器并调节其参数可以控制由充液井孔向地层中辐射的声波能量的方向,使声源向地层中的某个特定方向辐射的纵波能量得到明显提高. 在井间地震勘探和反射声波成像测井等领域中应用相控线阵声波辐射器,将有利于增大探测深度、提高探测分辨率和接收信号的信噪比.

We analyse the characteristics and feasibility of the linear phased array in acoustic well-logging by using FEM simulation. Numerical results show that if appropriate delay times of sources are exerted on elements of the phased array, direction of acoustic beam radiated from the phased array can be steered so that the refracted compressional wave and the refracted shear wave can be excited effectively. Moreover, if a lower frequency or weighted linear phased array is employed, the main lobe of the phased array can be widened so that the refracted compressional wave can be stimulated sufficiently in both hard and soft formation. Therefore, the linear phased array can be used to improve the quality of well-logging data and both signal-noise ratio and exploring capacity of acoustic well-logging radically.

本文根据流体饱和多孔介质中声传播的Biot理论和多孔介质界面上的六个边界条件研究了平面声波斜入射于多层水平板装多孔介质时的反射和透射.数值计算了快纵波为入射波时声波频率、入射角等量的变化对能量的反射系数、透射系数的影响。数值计算结果表明，当声波波长与中间介质厚度呈一定比例时，反射系数、透射系数取得极值，入射角、多孔介质的性质对反射系数、透射系数的影响很大。

多孔介质声学是近几年发展起来的应用性很强的声学分支。1956年Biot提出流体饱和多孔介质声传播理论, 奠定了该声学分支的理论基础。1980年Plona用实验证实在流体饱和多孔介质中存在包括Biot慢纵波在内的三种体声波, 对Biot理论的研究和用起了巨大的推动作用。后来, 人们对Biot理论进行了多方面的修正、完善, 使其成为最成功的多孔介质声学理论, 并广泛应用于资源的声波勘探和其它领域。

反射声波成像测井的分辨率和测量范围介于常规地震勘探和常规测井之间，在当前油气勘探的诸多领域尤其是随钻测井、大斜度井和水平井评价等复杂油气藏勘探和定量解释中具有实际意义。为此，对反射声波成像测井进行了物理模拟，制作了缩小比例的铝质和混凝土模型井，并用于模拟井旁不同倾角的声阻抗不连续界面对声波的反射。在充液环境下对反射声波模型井进行了实验测量，从全波波形上可以清楚地看到沿井壁传播的折射波和来自井旁声阻抗不连续界面的反射纵波。应用偏移叠加技术对物理模拟波形进行了反演处理，从偏移剖面上反演出的反射界面的尺寸、位置和倾角等几何特性与实验参数基本一致。

提出了在实验室内评价声波测井仪器的隔声体性能的评价方法。在实验室评价隔声体的性能时,应在隔声体的两端各连接一定长度的补偿管用于模拟隔声体上下两端的部件和消除边缘效应;应采用激震源和接收信号的三轴加速度计均放置在隔声体外侧两端的测量方案,用以消除不同加速度计的物理性能不一致对测量结果的影响。三轴加速度计作为接收探头可以评价隔声体的相互正交的3 个振动方向上的隔声量和时延量。给出了实现上述测量方案的实验装置和测量实例。

利用理论分析和实验模拟的方法研究了超声脉冲反射技术测量井下套管厚度的方法。研究结果表明, 垂直入射固体板并被反射的超声脉冲波的频谱在该板的共振频率取得极小值时出现谱陷, 利用谱陷频率可以比较准确地评价固体板的厚度。对于厚度范围为4～10mm的套管, 所用换能器的工作频率范围应为270～710kHz。

利用传递函数,得到了平面脉冲声波在传播过程中任意位置处频谱的计算方法,用这种方法可以评价脉冲声波的主频偏移程度。给出了多孔介质中脉冲快纵波主频偏移的数值计算实例。计算结果表明,在一个有限的频带内,介质的声衰减与频率近似成线性关系,脉冲声波的主频偏移与介质的衰减、场点距声源的距离呈正比。该结果有利于利用脉冲声波的主频偏移来评价介质的声衰减。