关键词: 横波远探测测井, 相干噪声, 不相干噪声, 地层界面波, 多次波, 坏道

Abstract: The extraction of reflected waves is a basic and key step during processing dipole acoustic reflection imaging data, and the extraction accuracy directly affects the imaging quality of near-borehole acoustical reflectors. The conventional extraction methods such as F-K filtering and Radon transformation generally ignore the noises generated under complex well and formation conditions, thus causing low extraction accuracy of reflectors and multi-solution of reservoir logging interpretation. Through analyzing the wave field characteristics of a large number of acoustic well logging data, this paper systematically determine two types of noises that affect the extraction accuracy of reflected waves:coherent noises and incoherent noises. The former mainly include formation interface wave and multiple wave, and the latter mainly include low- and high-frequency noise and bad channel. Through further research of the generation mechanisms, features, and identification methods of four kinds of noises, the noise suppression methods are developed, and S-wave reflected wave extraction method is proposed. Field application results indicate that the above method improves the extraction accuracy of reflected waves, makes the migration imaging of fractures and caves outside the borehole much clearer. This study can provide important technical support for oil-gas reservoir exploration and development.

Key words: dipole acoustic reflection imaging, coherent noise, incoherent noise, formation interface wave, multiple wave, bad channel