可用于地质导向的随钻声波远探测测井理论基础研究

With the breakthrough and important applications of remote acoustic reflection imaging in wireline logging environment, especially the dipole shear-wave reflection imaging technology, it has become important to expand this technology into LWD measurement, in which the propagation characteristics of the borehole acoustic wave have extremely changed, in order to address the need in drilling, strengthening its theoretical foundation and promoting field applications. Our approach consists of theoretical analysis, numerical simulation and laboratory measurement. We will study the radiation of multipole acoustic source mounted on the drill collar from borehole into formation and its receiving characteristic when used as a receiver. Through this study, we want to find the controlling factors affecting the measurement of acoustic reflection waves in LWD. This study will develop a fast computation method for LWD remote acoustic reflection imaging. The analysis will allow for optimizing the key parameters of LWD remote acoustic reflection imaging. The physical simulation using laboratory experiment will further rationalize optimized controlling parameters, verify the impact of drill collar on acoustic radiation and reception, providing a validation of feasibility for LWD remote acoustic reflection imaging. The purpose of this project is to propose an implementation scheme of applying the remote acoustic reflection imaging to the LWD environment. For the new field of LWD remote acoustic reflection imaging, the project results will provide a theoretical foundation and experimental support for this promising technology.

电缆测井条件下的声波远探测，尤其是偶极横波远探测技术，已取得了突破性的进展和重要应用，但在随钻声波远探测方面，由于测井环境的差异，井孔声波的传播特征发生了明显变化，还需在理论和方法上进行深入的研究，才能满足随钻地质导向的迫切需要。本项目拟采用理论分析、数值模拟和实验室测量相结合的研究路线，通过对钻铤上的多极子声源在钻铤和地层中的声场辐射及接收器对井处入射弹性波的接收响应研究，阐明声波与钻铤的相互作用效应，明确影响随钻声波远探测反射声场的主控因素；在此基础上，建立随钻声波反射声场快速计算及仪器参数优化方法，优选随钻声波远探测测井仪器的关键参数。结合物理模拟实验，进一步验证优选参数的合理性，研究钻铤的存在对声源辐射的影响以及随钻声波远探测测井仪器的测量效果验证方法。最终提出在随钻环境下进行声波远探测测井的实施方案，本项目的研究将为随钻声波远探测测井仪器的研发奠定理论基础与实验依据。

电缆测井条件下的声波远探测，尤其是偶极横波远探测技术，已取得了突破性的进展和重要应用，但在随钻声波远探测方面，由于测井环境的差异，井孔声波的传播特征发生了明显变化。本项目采用理论分析、数值模拟和实验室测量相结合的研究路线，通过对钻铤上的多极子声源在钻铤和地层中的声场辐射及接收器对井处入射弹性波的接收响应研究，阐明了声波与钻铤的相互作用效应，明确了影响随钻声波远探测反射声场的主控因素；在此基础上，针对弹性波入射充液井孔产生的散射和透射声场，给出了井孔对入射波的接收因子，推导了散射位移的渐近解形式，提出了一种快捷、有效地模拟远探测声场的解析方法，优选了随钻声波远探测测井仪器的最佳激发频段。与电缆偶极声源的情况相比，随钻条件下偶极声源的最大辐射效率明显降低，声源的优势激发频率也有所下降，并且受钻铤外径的影响较大。虽然，随钻测井中偶极声源的辐射效率有所降低，但由理论模拟的随钻偶极远探测数据的成像结果可知，声源辐射到地层中的能量仍足以探测井外反射体，从理论上初步证实了将偶极远探测技术引入到随钻测井中是可行的，这为随钻声波远探测探边技术提供了理论依据。结合物理模拟实验，进一步验证了优选参数的合理性，研究了钻铤的存在对声源辐射的影响以及随钻声波远探测测井仪器的测量效果验证方法。