纵波方位各向异性在河道砂体识别中的应用

Application of P-wave azimuthal anisotropy in channel-sand recognition.

(1.大庆石油管理局地球物理勘探公司,黑龙江大庆163357；2.中国科学院地质与地球物理所，北京100029；3.北京艾普斯特能源技术有限公司,北京100085)

Daqing Geophysical Exploration Company, Daqing 163357, China

松辽盆地北部扶杨油层属三角洲平原沉积，河道广泛发育，条带状发育的河道砂体具有很强的非均质性和各向异性。为此，基于河道砂体的沉积特点，借鉴储层裂缝的检测方法和技术，研究了薄互层河道砂体的振幅和频率随方位角的变化(AVA/FVA)规律。首先进行了岩石物理正演数值模拟，发现各向异性对方位角地震反射振幅的影响较大，而储层岩性的变化是影响各向异性的主要因素；然后对测井沉积微相与方位频率各向异性的统计分析进行了对比，结果表明，沉积旋回与方位频率各向异性有较好的对应关系，方位频率各向异性发育的区域对应物性较好的河道砂体的空间分布。

Fuyang reservoir in northern Songliao basin is a delta plain with well-developed channels of which the banded channel-sand is of strong heterogeneity and anisotropy. Therefore, based on the sedimentary characteristics of channel-sand, AVA/FVA features of thin inter-bedded channel-sand were studied in terms of detecting methods for reservoir fractures. Firstly, petrophysical forward modeling was carried out. The results show that the anisotropy has greater influence on azimuthal seismic reflection amplitude while some changes in reservoir lithology are the main impact factor for anisotropy. Then, logging sedimentary microfacies analysis was compared to the statistical analysis of azimuth-frequency anisotropy, showing that the sedimentary cycles are well corresponding to azimuth-frequency anisotropy. In addition, the area with strong anisotropy is the channel-sand where the physical properties are very good.