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131.
132.
利用煤层裂隙地震各向异性寻找煤层气气藏 总被引:5,自引:0,他引:5
煤层气是以吸附状态储集在煤层的微裂隙、裂缝中,煤层既是煤气的源岩层,也是煤层气的储集层。由于煤层裂隙的存在,将导致煤层的各向异性;根据横波分裂理论:横波通过方位各向异性介质时,横波将发生分裂现象,分裂为两个偏振方向近乎正交的横波,即传播方向平行于裂隙方向的快横波和传播方向垂直于裂隙方向的慢横波。本文介绍了煤层裂隙引起的横波分裂现象的实验室研究及实际野外试验成果。实际结果表明,利用转换横波探测煤层裂隙是可行的。本文最后给出了试验煤层裂隙发育范围和裂隙发育方向。 相似文献
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135.
Shi-Rong Mei 《地震科学(英文版)》1996,9(1):1-12
In this paper, the stress concentration process and the time-space distribution of stress when earthquakes are in preparation in one or more earthquake-generating bodies in a tectonic block have been analyzed and their relation with seismicity and earthquake precursors have been studied. The results show that: 1 When the regional stress field has intensified to a certain level, fracture begins in some block or blocks. The regional stress field will vary with time and the occurrence of strong earthquakes in groups is the result of the evolution of this dynamic stress field. In this process, the existence and development of more than one high stress concentration zone may give rise to a variety of pre-seismic anomaly-to-earthquake relations. 2 The process of stress variation in an earthquake-generating block generally appears as a nonlinear one. After the long-term elastic deformation, there may be more than one time of inelastic deformation and fault-softening from the beginning of the stage of inelastic deformation to just before the main fracture. Corresponding to such a nonlinearity, the stress and strain fields in the earthquake-generating block will display a complex pattern of time-space evolution; and thus the earthquake precursor fields controlled by stress and strain must display complexities in many aspects. 相似文献
136.
Seismic anisotropy beneath Southern Tibet 总被引:2,自引:0,他引:2
SeismicanisotropybeneathSouthernTibetQING-TIANLUI(吕庆田),KAI-YIMA(马开义),MEIJIANG'(姜枚),A.HirnandA.Nercessian(InstituteofMineralDe... 相似文献
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梅冥相 《沉积与特提斯地质》1996,16(6):24-33
与层序地层学定义的类型Ⅰ层序(LST+TST+CS+HST)及类型Ⅱ层序(SMT+TST+CS+HST)不同,淹没不整合型碳酸盐三级旋回层序以凝缩段直接覆盖在层序界面之上形成的,“CS+HST”序列为特征,而且其底界面为一淹没不整合面或加深饥饿间断面。该类型三级旋回层序是碳酸盐台地淹没事件产生的凝缩作用过程的产物,它以总体向上变浅的非对称相序为特征。华北北部晚寒武世地层中发育的四个淹没不整合型三级旋回层序的相序特征表明,台地淹没事件及其相关的凝缩作用,只要沉积背景适合,并非三级旋回层序所独有,高频率海平面变化也常产生“瞬时淹没”,因而凝缩段并非都发育在最大海侵期,并且凝缩段也存在级别归属问题。 相似文献
139.
This paper introduces how the ratioR of the characteristic stiffness of rock samplevs. the stiffness of testing machines would influence the rupturing process and the acoustic emission (AE) on the part of the
tested rock samples. Result of the experiment shows: WhenR>0.20, the rock sample would rupture abruptly; whereas whenR<0.20, the rock samples would rupture slowly. When the samples rupture abruptly, the time-dependent variation of the AE rate
takes such a pattern:peak value—stable low values—rises to the maximum value (concentration)—drops back to the minimum value
(quiescence)—(rises again)—ruptures. Moreover, smallerR-value tends to be associated with longer quiescence and vice versa. WhenR>1.50, no pre-failure quiescence is detected. When the rock samples rupture slowly, the variation pattern of the AE rate (after
the stress has increased to more than 50% of the rupturing stress) is as the following:stable low (or high) values—rises (or
drops) to its maximum (or minimum) values and then continues for some time—ruptures.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 223–233, 1991.
This study is supported by the Chinese Joint Seismological Science Foundation. 相似文献
140.
We have made a data collection and analysis system for recording microcracks in rock to study the three dimensional pattern
of fracture and the dynamic properties of rock during pressurization. This system, with 8 channel data detection, records
in real-time, from the initial microcracks to the final vibration waveform excited by the master fracture. The detected data
are recorded digitally at the hard disk of an IBM computer (or 286, 386 personal computer) as well as transmitted to disk.
The sampling rate for each channel is 10 MHz.
Collecting every acoustic emission events in the loaded rock sample with 8 channels by this system, mathematically modelling
the AE event travel time, and taking the coordinates of the AE event hypocenter and the three components of P wave velocity
as unknown parameters, we set up a set of residual equations for joint inversion, so that the three dimensional localization
of AE event hypocenters can be completed under variable velocities, which will lay foundations for the research on rock fracture
clearly.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismological Sinica,13, 489–495, 1991.
The design and development of the system, and the experiments are sponsored by the Chinese Joint Seismological Science Foundation. 相似文献