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一般来说,因为纵波受断裂的影响不很明显,因此常规的 P 波地震方法对勘探地下断裂不是很适用的。不过,近年来的理论研究和实验工作则表明,地下断裂的存在对横波的影响比较明显。地下的断裂体系通常由近似垂直、成线性排列的断裂系组成。它们在近于水平面的对称轴上形成明显的各向异性区域。横波一旦进入上述区域就会分成两个或两个以上不同速度和极性的几个相位。大量的研究表明,可通过采集三个方向的波动分量来记录和解释这种横波的分相和偏振特性。为了验证这一假说,Colorado 矿业学院地球物理系在已知的裂隙储集层上采集了五英里的三分量 P 波、SH 波地面地震可控震源资料。此外,在钻井附近还采集了三分量 P 波。SH 波的VSP 资料。这项研究的费用是由一个13家企业组成的赞助团体提供的,1985年11月完成了资料的采集工作。
In general, conventional P-wave seismic methods are not suitable for the exploration of underground faults because the longitudinal waves are not significantly affected by the fracture. However, in recent years, theoretical research and experimental work have shown that the existence of underground faults on the shear wave more obvious. Underground fracture systems are usually composed of nearly vertical, linear arrangement of faults. They form distinct areas of anisotropy on an axis of symmetry near the horizontal. As soon as the transverse waves enter these areas, they are split into two or more phases of different velocities and polarities. Numerous studies have shown that the phase-separation and polarization characteristics of this shear-wave can be recorded and explained by collecting the fluctuation components in three directions. To test this hypothesis, the Department of Geophysics at the Colorado School of Mines collected five-mile, three-component P-wave and SH-wave ground-based seismic vibroseis data on known fractured reservoirs. In addition, a three-component P wave was collected near the well. SH wave VSP data. The cost of the study was provided by a sponsoring group of 13 companies and the data collection was completed in November 1985.