Calculation of elastic properties in lower part of the Kola borehole from bulk chemical compositions of core samples
Calculation of elastic properties in lower part of the Kola borehole from bulk chemical compositions of core samples
复制标题
根据岩心样品的大量化学成分计算科拉钻孔下部的弹性特性
DOI：
--
复制
发表时间：
1994
期刊：
影响因子：
--
通讯作者：
N. A. Derevschikova
中科院分区：
文献类型：
--
作者：
A. Babeyko;S. Sobolev;E. Sinelnikov;Y. Smirnov;N. A. Derevschikova
深井中的原位弹性性质受多种因素控制，主要是岩性、岩组、充满流体的裂缝和孔隙。为了区分不同因素的影响，从实测速度中提取岩性控制部分是有用的。为此，我们计算了矿物组成和各向同性无裂纹的弹性性能在科拉钻孔的下部，从大量的岩心样品的化学成分。我们使用了一种新的技术，岩石物理模拟的基础上热力学方法。通过与高围压下上地壳结晶岩的矿物成分观测值和密度及弹性波速度的实验室测量值的比较，证实了模型的合理精度。对6840- 10535 m深度段的896个岩心样品进行了计算。使用这些结果，我们估计密度和无裂纹的各向同性弹性特性的554岩性定义层组成的这个深度段。平均合成纵波速度比垂直地震剖面（VSP）速度高2.7%，比声波测井速度高5%。平均合成横波速度比VSP高1.4%。这些差异可以解释为叠加的织物相关的各向异性的影响，平行于叶理平原对齐的裂纹，随机取向的裂纹，与裂纹的效果是主要的控制。低声波测井速度可能是由钻孔壁中的钻井诱导裂缝（水力压裂）引起的。计算出的合成密度和速度截面可用于更详细的解释，但这需要新的、更详细和可靠的地震数据。
In-situ elastic properties in deep boreholes are controlled by several factors, mainly by lithology, petrofabric, fluid-filled cracks and pores. In order to separate the effects of different factors it is useful to extract lithology-controlled part from observedin-situ velocities. For that purpose we calculated mineralogical composition and isotropic crack-free elastic properties in the lower part of the Kola borehole from bulk chemical compositions of core samples. We use a new technique of petrophysical modeling based on thermodynamic approach. The reasonable accuracy of the modeling is confirmed by comparison with the observations of mineralogical composition and laboratory measurements of density and elastic wave velocities in upper crustal crystalline rocks at high confining pressure. Calculations were carried out for 896 core samples from the depth segment of 6840–10535m. Using these results we estimate density and crack-free isotropic elastic properties of 554 lithology-defined layers composing this depth segment. Average synthetic P- wave velocity appears to be 2.7% higher than the velocity from Vertical Seismic Profiling (VSP), and 5% higher than sonic log velocity. Average synthetic S-wave velocity is 1.4 % higher than that from VSP. These differences can be explained by superposition of effects of fabric-related anisotropy, cracks aligned parallel to the foliation plain, and randomly oriented cracks, with the effect of cracks being the predominant control. Low sonic log velocities are likely caused by drilling-induced cracking (hydrofractures) in the borehole walls. The calculated synthetic density and velocity cross-sections can be used for much more detailed interpretations, for which, however, new, more detailed and reliable seismic data are required.