断裂带热释光的初步研究

本文对湖南水口山矿田断裂带岩石进行了热释光分析,断裂作用可对岩石的热释光特征产生显著变化。断裂带岩石天然热释光不存在250℃以下的低温峰;从围岩到断裂带中心,热释光峰值大幅度增加;同一断裂带从地表向深部热释光峰值增加。碎裂断裂带天然热释光峰值为10~3—10~4级,高峰温度位于290—310℃范围内;硅化断裂带的天然热释光峰值大多为10~2—10~3级,高峰温度多在330—350℃范围内。     

四川省青川断裂的特征及形成的物理条件

本文详细地讨论了四川省青川断裂的断裂特征及形成的物理条件。对断裂构造岩的微构造和宏观构造进行了细致的描述分析,将断裂岩分为四个带。结合区域资料,讨论了断裂的形成时代及与邻区的关系。     

非等间距序列的灰色预测模型及其在岩石蠕变断裂中的应用

给出了非等间距序列的灰色预测模型，讨论了该模型的灰色预测平面和最优预测函数。最一将该模型应用于符合Ｋｅｌｖｉｎ模型的岩石材料的蠕变断裂研究，给出了应用实例，并验证了该方法的可行性。     

从钠溪气田看阳新统裂缝型气藏分布复杂性

本文以纳溪气田的实际资料，特别是纳６井裂缝系统的典型资料，裂缝系统在纵横向上的分布具明显的方向性和系统中流体分布异常，剖析川南地区二叠系阳新统裂缝型气藏分布的复杂性，为裂缝型气藏的勘探提供借鉴。     

Hydrofracture mechanisms in rock during pressure grouting

Summary Hydrofracture Mechanisms in Rock During Pressure Grouting. The paper examines the basic meachnisms controlling the initiation of fractures in rocks and layered soils during pressure grouting, and their subsequent propagation into the ground mass. Previous analyses of fracture initiation have tended to concentrate on simplified models in which the ground is treated as an impervious elastic or Mohr-Coulomb continuum. The present method allows for the porous or fissured nature of the ground by considering the effect of seepage forces induced by the pore pressure gradient. The effect is quantified by use of a parameterN such that the ratio of fluid force used in expanding the injection hole, to that used in forcing fluid through void spaces, isN to (1—N).Analysis of hydrofracture propagation is based on stress analysis of a borehole in an elastic continuum, the propagating fracture zone around the borehole being represented as a non-elastic material governed by the Mohr-Coulomb failure criterion. This is supplemented by an energy approach which equates the energy supplied to the ground from the injection pump, with the energy stored in the ground and the energy necessary to fracture it.

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Zusammenfassung Brucherscheinungen im Fels bei Verprearbeiten. In der Arbeit wird der grundlegende Mechanismus untersucht, welcher bei Verpreßarbeiten in Fels und geschichtetem Boden zur Einleitung und Ausbreitung von Brüchen führt. Frühere Untersuchungen des Bruchbeginns stützten sich im wesentlichen auf vereinfachte Modelle, in denen der Untergrund als undurchlässiges Kontinuum angesehen wird, das entweder elastisch ist oder der Mohr-Coulombschen Bruchbedingung genügt. Die neue Methode berücksichtigt dagegen eine Porosität oder Klüftung des Untergrundes durch Ansatz der vom strömenden Medium auf das Gebirge ausgeübten Belastung. Diese Belastung wird aufgeteilt in einen Druckverlust an der Bohrlochwand (gleich ParameterN mal Verpreßdruck) und die entsprechende, über den gesamten durchströmten Bereich verteilte Belastung.Die Untersuchung der Bruchausbreitung geht von der Spannungsermittlung um ein Bohrloch in einem elastischen Kontinuum aus, wobei in der sich ausbreitenden Bruchzone um das Bohrloch herum nichtelastisches Material angenommen wird, das dem Mohr-Coulombschen Bruchkriterium genügt. Zur Ergänzung dient eine Energie-Betrachtung, bei der die von der Injektionspumpe abgegebene Energie gleichgesetzt wird der im Untergrund gespeicherten Energie und der aufgewendeten Brucharbeit.

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Résumé Les mécanismes de la fracturation hydraulique dans les roches pendant les injections sous pression. Le mémoire examine les mécanismes fondamentaux qui gouvernent l'initiation des ruptures dans les roches et les sols stratifiés, au cours des injections et leur propagation dans les massifs. Les analyses antérieures de l'initiation de la rupture, se sont concentrées sur des modèles simplifiés où l'on considérait la roche comme un milieu élastique et imperméable, ou comme un milieu de Mohr-Coulomb. La présente méthode admet que le massif est poreux ou fissuré, en considérant l'action des forces de percolation engendrées par le gradient de pression interstitielle. Cette action est quantifiée par un paramètreN, tel que le rapport de la force du liquide employée à dilater le forage d'injection, à celle employée pour forcer le coulis à travers les vides soitN/(1—N). L'analyse de la propagation des ruptures se base sur l'analyse des contraintes autour d'un forage dans un milieu élastique, alors que la zone de la rupture qui se propage autour du forage est représentée par un milieu non-élastique admettant le critère de rupture de Mohr-Coulomb. Cette analyse est complétée par une approche énergétique, où l'énergie qui est fournie au massif par la pompe d'injection est égalée à l'énergie emmagasinée dans la roche et à l'énergie de rupture.

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Nomenclature A area of new cracks created per unit volume of time t - E total work done by injection fluid - E _i irrecoverable component of energy - E _{i c} work done in fracturing rock or soil - E _{i l} work done to overcome various frictional forces in grouting system - E _{i p} work done to cause plastic deformation of fractured zone - E _{i s} work done to overcome shear strength of fluid during flow - E _{i v} work done to overcome frictional drag between fluid and rock in soil surfaces during flow - E _r recoverable component of energy - E _{r f} elastic strain energy stored in fluid - E _{r s} elastic strain energy stored in rock or soil - h height of overburden - i j 1, 2, 3 - K ₀ coefficient of horizontal earth pressure - k permeability of ground to grout - L length of cylindrical grout source - n rock or soil porosity - p average fluid pressure between timet and (t + t) - p ₀ injection pressure - R radius of grout front - r radial distance from borehole axis - r ₀ radius of borehole - r ₁ radius of fractured zone - S specific surface area of rock or soil - S _T tensile strength of rock or soil - t time - u grout seepage velocity - V volume of grout injected - v volumetric strain - specific surface energy of rock - bulk density of rock or soil - _{i j} ^e elastic strain increment tensor - _{i j} plastic strain increment tensor - v Poisson's ratio - _{i j} average stress tensor in the ground during timet and (t + t) - _R , _T, _Z radial, tangential and vertical stresses induced by grouting - _r , _t , _z radial, tangential and vertical stress around borehole before grouting - grout shear strength - angle of internal friction of rock or soil With 7 Figures     

Cenozoic post-collisional brittle tectonic history and stress reorientation in the High Zagros Belt (Iran, Fars Province)

The Zagros fold-and-thrust belt of SW-Iran is among the youngest continental collision zones on Earth. Collision is thought to have occurred in the late Oligocene–early Miocene, followed by continental shortening. The High Zagros Belt (HZB) presents a Neogene imbricate structure that has affected the thick sedimentary cover of the former Arabian continental passive margin. The HZB of interior Fars marks the innermost part of SE-Zagros, trending NW–SE, that is characterised by higher elevation, lack of seismicity, and no evident active crustal shortening with respect to the outer (SW) parts. This study examines the brittle structures that developed during the mountain building process to decipher the history of polyphase deformation and variations in compressive tectonic fields since the onset of collision. Analytic inversion techniques enabled us to determine and separate different brittle tectonic regimes in terms of stress tensors. Various strike–slip, compressional, and tensional stress regimes are thus identified with different stress fields. Brittle tectonic analyses were carried out to reconstruct possible geometrical relationships between different structures and to establish relative chronologies of corresponding stress fields, considering the folding process. Results indicate that in the studied area, the main fold and thrust structure developed in a general compressional stress regime with an average N032° direction of σ₁ stress axis during the Miocene. Strike–slip structures were generated under three successive strike–slip stress regimes with different σ₁ directions in the early Miocene (N053°), late Miocene–early Pliocene (N026°), and post-Pliocene (N002°), evolving from pre-fold to post-fold faulting. Tensional structures also developed as a function of the evolving stress regimes. Our reconstruction of stress fields suggests an anticlockwise reorientation of the horizontal σ₁ axis since the onset of collision and a significant change in vertical stress from σ₃ to σ₂ since the late stage of folding and thrusting. A late right-lateral reactivation was also observed on some pre-existing belt-parallel brittle structures, especially along the reverse fault systems, consistent with the recent N–S plate convergence. However, this feature was not reflected by large structures in the HZB of interior Fars. The results should not be extrapolated to the entire Zagros belt, where the deformation front has propagated from inner to outer zones during the younger events.     

Mesozoic extension in the Basque–Cantabrian basin (N Spain): Contributions from AMS and brittle mesostructures

In this work we analyse and check the results of anisotropy of magnetic susceptibility (AMS) by means of a comparison with palaeostress orientations obtained from the analysis of brittle mesostructures in the Cabuérniga Cretaceous basin, located in the western end of the Basque–Cantabrian basin, North Spain. The AMS data refer to 23 sites including Triassic red beds, Jurassic and Lower Cretaceous limestones, sandstones and shales. These deposits are weakly deformed, and represent the syn-rift sequence linked to basins formed during the Mesozoic and later inverted during the Pyrenean compression. The observed magnetic fabrics are typical of early stages of deformation, and show oblate, triaxial and prolate magnetic ellipsoids. The magnetic fabric seems to be related to a tectonic overprint of an original, compaction, sedimentary fabric. Most sites display a NE–SW magnetic lineation that is interpreted to represent the stretching direction of the Early Cretaceous extensional stage of the basin, without recording of the Tertiary compressional events, except for sites with compression-related cleavage.Brittle mesostructures include normal faults, calcite and quartz tension gashes and joints, related to the extensional stage. The results obtained from joints and tension gashes show a dominant N–S to NE–SW, and secondary NW–SE, extension direction. Paleostresses obtained from fault analysis (Right Dihedra and stress inversion methods) indicate NW–SE to E–W, and N–S extension direction. The results obtained from brittle mesostructures show a complex pattern resulting from the superposition of several tectonic processes during the Mesozoic, linked to the tectonic activity related to the opening of the Bay of Biscay during the Early Cretaceous. This work shows the potential in using AMS analysis in inverted basins to unravel its previous extensional history when the magnetic fabric is not expected to be modified by subsequent deformational events. Brittle mesostructure analysis seems to be more sensitive to far-field stress conditions and record longer time spans, whereas AMS records deformation on the near distance, during shorter intervals of time.     

一个韧性转换挤压带的变形分解作用：以阿尔金断裂带东段为例

变形构造研究显示阿尔金划分成具有近水平拉伸线理的韧性左行走滑变形域和具有陡角度倾伏拉伸线理的收缩变形域。在ＳＳ与ＰＳ之间的过渡区域还发现中等角度倾伏的拉伸线理。     

Burst strain disturbance — A new test study on fracture precursor

A multi-functional high-frequency seismometer, a new instrumental system, is used for recording multi-point strain variations of rock samples in the process of fracture development. The results indicate that strain in each point appears burst disturbance synchronously besides a tendency variation before main fracture. The burst disturbance could probably be one of the short-impending precursors before great earthquake.     

储层裂缝特征测井解释方法综述

为了更好地研究裂缝性砂砾岩储层和其它裂缝性储层裂缝的测井解释问题,综述了目前在裂缝性储层裂缝测井解释中主要采用的常规评价、人工神经网络和斯通利波３类方法在识别裂缝带和定量计算储层裂缝参数两个方面的应用原理和研究现状,并指出了今后的一些研究方向。