随钻声波测井仪隔声结构研究

Acoustic logging while drilling (LWD) is one of the key technologies for discovery and identification of reservoirs. In LWD wave velocity measurments, a drill collar mode wave propagating along the drill collar could be excited, and its amplitude is large enough to cover up the useful signals. It is necessary to suppress and isolate the drill collar mode wave for getting better formation wave information. So design of acoustic insulation structure is particularly important for acoustic LWD instruments. Compared to foreign researches, however,the related internal researches on acoustic insulation structure of acoustic LWD is still in the basic research stage. In this application,theoretical analysis, numerical simulation and experimental measurement methods are used to study the principles and explore effective solution of acoustic insulation structure in acoustic LWD. By studying acoustic propagation in the acoustic insulation structure with finite-length, analyze the frequency domain characteristics of mode wave spreading in it. By referencing reasearch methods of phononic crystals, study the band gaps of insulation structures in LWD, study relationship between acoustic attenuation characteristics and the various parameters, analyze the frequency domain and insulation of acoustic insulation structure. Then by carrying out sample experimental measurement, verify the reliable of similation results. Based on the above studies, a new effective program for designing acoustic insulation structure that satisfying acoustic LWD could be proposed. These works could lay a reliable theoretical basis and experimental evidence for the design of acoustic insulation structure in acoustic LWD.

随钻声波测井是用于发现识别油气的随钻测井核心技术之一。在声速的随钻测量中，会激发一种沿钻铤传播的钻铤模式波，该模式波在波列中占主导地位，必须采用隔声结构对其进行压制和隔离才能测到有效信号。因此，随钻声波测井仪器的隔声结构设计显得尤为重要。相比于国外，目前国内对于随钻声波测井仪器隔声结构的研究尚处于研发验证阶段。本项目拟通过理论分析、数值仿真和实验测量等方法研究随钻声波测井隔声结构的原理并寻找有效方案。考察有限长随钻声波测井仪隔声结构的声传播规律，分析其中模式波的频域特征；借鉴声子晶体的设计思路，研究随钻声波隔声结构的带隙特征，考察该结构的声衰减特性与各参数之间的关系、隔声频带范围以及隔声量的大小。然后，开展小样实验测量，并与理论模拟结果进行对比验证。通过上述理论和实验研究，给出一种新型的、有效的随钻声波测井的隔声结构的设计原理与方案，为随钻声波测井仪器的研发奠定可靠的理论基础和实验依据。

随钻声波测井是用于发现识别油气的随钻测井核心技术之一。在声速的随钻测量中，会激发一种沿钻铤传播的钻铤模式波，该模式波在波列中占据主导地位，必须采用隔声结构对其进行压制和隔离才能测到有效信号。因此，随钻声波测井仪器的隔声结构设计显得尤为重要。相比国外，国内对于随钻声波测井仪器隔声结构的研究尚处于研发验证阶段。项目通过理论分析、数值仿真和实验测量的方法研究随钻声波测井隔声结构的原理并寻求有效方案。考察了有限长随钻声波测井仪隔声结构的声传播规律，分析了其中模式波的频域特征；借鉴声子晶体的设计思路，研究了不同类型晶格结构随钻声波隔声结构的带隙特征，考察了声衰减与各参数之间的关系，隔声频带及隔声量的大小。搭建了一套隔声结构声衰减测试系统，开展了小样隔声结构试验测量，并与理论仿真结果进行了对比验证。对随钻声波隔声结构的机械性能进行了初步仿真研究。在数值仿真的基础上，在保证现场施工安全的条件下，提出了一种环形刻槽周期结构的一维声子晶体模型的设计原理与方案，衰减频带在10-15kHz，声衰减量达到35dB，并成功应用于随钻声波实验样机的研发中。项目研究实现了利用数值仿真对实际隔声结构设计及测试的指导作用，避免设计失误造成的成本浪费。为随钻声波测井仪器隔声结构乃至电缆测井隔声结构研制提供了可靠的理论支撑和实验依据。