摘要：The conventional acoustic logging interpretation method, which is based on vertical wells that penetrate isotropic formations, is not suitable for horizontal and deviated wells penetrating anisotropic formations. This unsuitability is because during horizontal and deviated well drilling, cuttings will splash on the well wall or fall into the borehole bottom and form a thin bed of cuttings. In addition, the high velocity layers at different depths and intrinsic anisotropy may affect acoustic logging measurements. In this study, we examine how these factors affect the acoustic wave slowness measured in horizontal and deviated wells that are surrounded by an anisotropic medium using numerical simulation. We use the staggered-grid finite difference method in time domain (FDTD) combined with hybrid-PML. First, we acquire the acoustic slowness using a simulated array logging system, and then, we analyze how various factors affect acoustic slowness measurements and the differences between the effects of these factors. The factors considered are high-velocity layers, thin beds of cuttings, dipping angle, formation thickness, and anisotropy. The simulation results show that these factors affect acoustic wave slowness measurements differently. We observe that when the wavelength is much smaller than the distance between the borehole wall and high velocity layer, the true slowness of the formation could be acquired. When the wavelengths are of the same order (i.e., in the near-field scenarios), the geometrical acoustics theory is no longer applicable. Furthermore, when a thin bed of cuttings exists at the bottom of the borehole, Fermat's principle is still applicable, and true slowness can be acquired. In anisotropic formations, the measured slowness changes with increments in the dipping angle. Finally, for a measurement system with specific spacing, the slowness of a thin target layer can be acquired when the distance covered by the logging tool is sufficiently long. Based on systematical simulations with different dipping angles and anisotropy in homogenous TI media, slowness estimation charts are established to quantitatively determine the slowness at any dipping angle and for any value of the anisotropic ratio. Synthetic examples with different acoustic logging tools and different elastic parameters demonstrate that the acoustic slowness estimation method can be conveniently applied to horizontal and deviated wells in TI formations with high accuracy.

关键字：Horizontal well deviated well high velocity layer cuttings bed acoustic slowness estimation

ISSN号：1672-7975

卷、期、页：卷: 14 期: 3 页: 337-350

发表日期：2017-09-01

期刊分区（SCI为中科院分区）：四区

收录情况：SCIE（科学引文索引网络版）,CSCD（中国科技引文期刊）（核心）,ESI（基本科学指标数据库）

发表期刊名称：Applied Geophysics

参与作者：张阔

通讯作者：刘鹤

第一作者：王兵,陶果,岳文正

论文类型：期刊论文

论文概要：刘鹤,王兵,陶果,张阔,岳文正，Study on the simulation of acoustic logging measurements in horizontal and deviated wells，Applied Geophysics，2017，卷: 14 期: 3 页: 337-350

论文题目：Study on the simulation of acoustic logging measurements in horizontal and deviated wells