Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away fr...Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away from the borehole. Remote acoustic logging uses phase-controlled array-transmitting and long sound probes that increase the depth of investigation. The interpretation of logging data with respect to fractures is typically guided by practical experience rather than theory and is often ambiguous. We use remote acoustic reflection logging data and high-order finite-difference approximations in the forward modeling and prestack reverse-time migration to image fractures. First, we perform forward modeling of the fracture responses as a function of the fracture-borehole wall distance, aperture, and dip angle. Second, we extract the energy intensity within the imaging area to determine whether the fracture can be identified as the formation velocity is varied. Finally, we evaluate the effect of the fracture-borehole distance, fracture aperture, and dip angle on fracture identification.展开更多
基金supported by National Petroleum Major Project(Grant No.2011ZX05020-008)
文摘Fracture identification is important for the evaluation of carbonate reservoirs. However, conventional logging equipment has small depth of investigation and cannot detect rock fractures more than three meters away from the borehole. Remote acoustic logging uses phase-controlled array-transmitting and long sound probes that increase the depth of investigation. The interpretation of logging data with respect to fractures is typically guided by practical experience rather than theory and is often ambiguous. We use remote acoustic reflection logging data and high-order finite-difference approximations in the forward modeling and prestack reverse-time migration to image fractures. First, we perform forward modeling of the fracture responses as a function of the fracture-borehole wall distance, aperture, and dip angle. Second, we extract the energy intensity within the imaging area to determine whether the fracture can be identified as the formation velocity is varied. Finally, we evaluate the effect of the fracture-borehole distance, fracture aperture, and dip angle on fracture identification.
文摘逆时偏移已成为复杂陡倾角构造成像的标准工具.当地下构造含有强衰减体时会强烈的吸收高频能量,导致地震波的振幅减弱和相位失真,常规的逆时偏移技术难以获得较高的成像分辨率.因此,如何在逆时偏移中进行Q补偿(Q-Compensated Reverse Time Migration,Q-RTM),包括幅值补偿和相位矫正,是有效地提高含强衰减特征的复杂地质构造的成像分辨率,并使反射界面在正确位置成像的热门研究方向.但是,在Q-RTM的波场延拓中同时补偿幅值和矫正相位并不那么容易实现,而且在地震波能量补偿过程中放大的高频噪声会引起稳定性问题,这些都是Q-RTM当前需要解决的主要问题.因此,本文首先回顾了Q-RTM近年来的发展现状,介绍了Q-RTM的基本原理和成像条件,分析了当前存在的主要问题及其解决方法,并展望了Q-RTM的未来发展方向.
