吉林冰湖沟隐爆角砾岩型金矿床地质特征及成因探讨

冰湖沟隐爆角砾岩型金矿床为溜河高级变质区近年来新发现的金矿工业类型,角砾岩产于多组构造交汇部的二长花岗岩中,金矿化与中生代浅成—超浅成中—酸性侵入岩有成因联系。文章通过对冰湖沟隐爆角砾岩型金矿床地质特征的分析和阐述,初步探讨了隐爆角砾岩体形成机理及矿床成因。推断矿床大致形成于白垩纪,属中—低温热液角砾岩型矿床。     

河南祁雨沟隐爆角砾岩筒的侧向隐爆模式探讨

隐爆角砾岩筒的成岩作用方式可分为底侵隐爆和侧向隐爆,不同方式形成的隐爆角砾岩筒,其控矿特征不尽相同,并可能形成不同的矿床类型组合.在地质勘查工作中,要根据不同类型的隐爆角砾岩筒,有针对性地寻找相关类型矿床.在底侵隐爆形成的隐爆角砾岩筒的深部可能会存在斑岩型矿床,但在侧向隐爆形成的隐爆角砾岩筒的深部,由于其底部与围岩直接接触,表现为“无根”,因此,不存在斑岩型矿床的可能.通过研究,认为祁雨沟矿田内隐爆角砾岩筒的成岩作用方式为侧向隐爆,隐爆角砾岩筒表现为“无根”角砾岩筒,为残缺的斑岩成矿系统,在隐爆角砾岩筒的深部不存在斑岩型矿床的可能.     

内蒙古义盛店铀银多金属矿床地质特征及成因探讨

义盛店铀银多金属矿区位于西干沟大型破火山机构的北侧,铀银多金属矿主要产于次火山岩体内的隐爆角砾岩中及次火山岩体盖层中。文章介绍了义盛店次火山岩型铀银多金属矿床的地质特征,分别从矿体(层)赋存规律、成矿物质来源、控矿构造特征、成矿环境分析等方面对其矿床成因进行了探讨,总结了成矿模式。     

吉林三道溜河冰湖沟隐爆角砾岩型金矿床地质特征及找矿方向

三道溜河冰湖沟隐爆角砾岩型金矿床位于华北地台北缘东段太古宙高级变质区,出露岩石主要为变质深成岩.区内的隐爆角砾岩体展布受EW和NE向韧性剪切带控制.通过对冰湖沟隐爆角砾岩型金矿床的地质特征、矿化富集规律、控矿因素及地球化学、地球物理异常特征的研究表明,金矿体受隐爆角砾岩体和NE向韧性剪切带联合控制,成矿与中生代浅成低温...     

祁漫塔格克停哈尔隐爆角砾岩成矿地质特征及找矿意义

克停哈尔矿区位于青海省祁漫塔格成矿带东端,矿区出露地层有古元古界金水口岩群和寒武—奥陶系滩间山群,岩性以片麻岩、大理岩为主。侵入岩以印支期花岗闪长岩为主,是斑岩型钼矿含矿母岩;北西向的压扭性断裂为矿区主体构造,后期北东向构造为成矿提供了良好通道,是热液脉型多金属矿的主要产出部位,矿区花岗闪长岩体中发育隐爆角砾岩,2016年在隐爆角砾岩中新发现了铅锌矿,是祁漫塔格成矿带发现的第二例隐爆角砾岩型多金属矿,通过对矿区隐爆角砾岩筒初步研究分析认为,其剥蚀程度浅,保存较完整,深部具有良好的找矿前景。总结该区隐爆角砾岩成矿特征,以期为祁漫塔格成矿带同类型矿床勘查提供参考。     

山东五莲七宝山长老庄隐爆角砾岩特征及其找矿指示

隐爆角砾岩是火山活动中,在地表封闭条件下发生剧烈爆炸所形成的碎屑岩建造,具有良好的热液成矿通道。五莲七宝山地区火山活动频繁,发育多期次火山杂岩体,形成七宝山火山机构。通过本次工作,在七宝山火山机构的南部,新发现长老庄隐爆角砾岩带,发现铜铅矿体1个,矿体呈脉状赋存在隐爆角砾岩带中,赋矿岩石为碳酸盐化、硅化、金属矿化隐爆角砾岩,矿体厚3 m,铜品位0.272%～0.823%,平均品位0.45%;铅品位0.240%～2.872%,平均品位为0.45%。通过对隐爆角砾岩带的地质特征综合分析,沿含矿角砾岩筒的通道相有可能追索到深部的斑岩型矿化。     

张麻井铀钼矿床地质特征及沽源盆地找矿思路

燕山造山带形成于中生代,由于构造、火山活动,产生一系列断陷盆地,与隆起带相间出现,有等间距特点。张麻井大型铀钼矿床位于蔡家营—双脑包次级火山构造洼陷带内。主要为次流纹斑岩体控制,赋存于次流纹斑岩体顶部隐爆角砾岩中。在古太古代末基底发生强烈变质作用,成矿元素第一次富集。中生代的火山热液活动,成矿元素第二次富集。经多期次热液活动,在隐爆角砾岩部位形成富矿体。     

内蒙古官地冰长石—绢云母型银金矿床地质特征及找矿标志

官地银金矿床位于华北地台北缘早古生代造山带内,为一冰长石—绢云母型(低硫型)浅成低温热液矿床。矿床的形成和分布严格受火山机构及与其有关的北西向断裂构造控制,矿体赋存于闪长岩、闪长玢岩、流纹斑岩和隐爆角砾岩内,多呈脉状产出。典型蚀变有硅化、绢云母化、黄铁矿化、冰长石化、碳酸盐化、高岭土化、绿泥石化等,并围绕矿体具有一定的蚀变分带。硅化、冰长石化、隐爆角砾岩以及铁锰帽是其重要的找矿标志,为矿区及其外围找矿指明了方向。     

某银铅锌多金属矿特征及成因分析

本文分析了某银铅锌多金属矿地质特征及成因分析,并阐述了银、铅、锌的成矿规律。矿体严格受断裂构造和花岗岩体控制,燕山期深部岩浆为成矿提供成矿物质,北西向断裂构造为成矿提供运移通道和容矿空间。得出该矿床为构造—岩浆热液作用中低温热液脉状硫化物矿床。     

东昆仑克停哈尔斑岩型铜钼矿成矿特征及找矿方向

东昆仑克停哈尔地区物化探异常丰富,古元古界金水口岩群大理岩是成矿有利地层,印支期似斑状花岗闪长岩为铜钼矿含矿围岩,岩体中有小的隐伏斑岩体及隐爆角砾岩筒,岩体内北东向构造裂隙发育,围绕岩体已形成了斑岩型铜钼矿、夕卡岩型铁多金属矿及热液脉型铜铅锌多金属矿的岩浆热液成矿系列。由岩体往外依次出现钼、铜、铅锌矿化的分带性,总结区域及矿区地质特征认为,结合物化探异常加强隐爆角砾岩筒为中心的似斑状花岗闪长岩体及花岗斑岩体勘查,将是后期找矿工作的重点。     

含夹层盐岩双重介质耦合损伤模型研究

针对中国地下油气储库建设中所出现的含夹层盐岩问题,考虑夹层和盐岩层之间存在地质界面,采用以节点位移和孔隙压力为自由度的界面单元来模拟水力损伤造成的地层界面的开裂、扩展和流体渗漏;并基于多孔介质流–固耦合理论,建立含夹层盐岩双重介质耦合损伤模型。该模型克服了等效连续介质模型不能正确反映地层界面的渗流问题,又克服了双重介质模型不能考虑地层界面开裂问题。在此基础上,采用数值模拟技术,研究高压流体在泥岩夹层与盐岩的界面渗透及其开裂扩展特征,结果表明,高压流体沿腔体围岩渗漏过程中,含夹层盐岩界面呈扇形状张开,沿界面通道流体压力逐步降低。因此,在层状盐岩储库运营过程中,要严格控制腔体压力,避免在含夹层盐岩分层界面上产生油气渗漏,保持腔体的致密性及稳定性。     

鄂尔多斯盆地麻地沟地区长6储层敏感性分析

鄂尔多斯盆地麻地沟地区长6储层属于低孔、特低渗储层,储层渗流条件较差。为厘清储层敏感性对渗流条件的影响以及储层的损害机理,通过X衍射、全岩定量分析、薄片鉴定、室内岩芯流动实验等,对研究区长6储层进行了敏感性评价。结果表明,麻地沟地区长6储层具有弱水敏、弱酸敏、弱碱敏、中等偏弱盐敏以及弱速敏等特征。针对储层敏感性问题,可采用注入与储层内流体水质相同或相近的水、压裂和酸化等措施改造、控制入井流体的p H值、调节注入储层流体的矿化度、控制注水速度等措施使其增产。实验结果可为研究区长6低渗透油藏的可持续开发和保护提供理论依据。     

Effects of Sand Permeability and Weak Aftershocks on Earthquake-Induced Lateral Spreading

Centrifuge research conducted at Rensselaer Polytechnic Institute (RPI) is summarized focusing on the effect of sand permeability and of weak aftershocks on earthquake-induced lateral spreading. One-dimensional shaking tests were conducted in a laminar box at a centrifugal acceleration of 50 g, simulating a 10 m thick homogeneous layer of clean Nevada sand of relative density 40-45% inclined a few degrees to the horizontal. Seven centrifuge experiments were done using either water or a viscous pore fluid fifty times more viscous than water, thus varying the soil permeability by a factor of fifty and simulating either a coarse prototype sand or a fine sand in the field. These seven tests were subjected to the same shape of base input excitation but with peak input accelerations ranging from 0.18 g to 0.46 g between tests. An additional special centrifuge test of a similar model with viscous pore fluid was subjected to a strong base “main shock”, followed after a few seconds by two “weak aftershocks”. Excess pore pressures, accelerations, settlements and lateral ground deformations were measured. The results are discussed in detail and several correlations are presented between testing and measured parameters such as thickness of liquefied soil, ground surface settlement, lateral ground displacement and input peak acceleration. The results of the special test, together with other evidence, provide strong support to the hypothesis that reported continued ground deformations from lateral spreads in the field are often caused by continued weak vibration or aftershocks occurring after the main shock.     

青海多日茸铅锌多金属矿床成矿流体特征及矿床成因

青海多日茸铅锌多金属矿床是我国重要的铜铅锌多金属矿产资源基地之一,但该矿床形成机理研究尚浅,制约了对矿床特征的认识。为了科学评价研究区矿产资源,在收集前人区域成果的基础上,开展野外地质调查,分析成矿流体性质,探讨矿床成因。研究结果表明:包裹体主要为气液两相包裹体和纯CO_2包裹体,包裹体流体属于H_2O-CH_4-N_2-NaCl体系,表明成矿流体为低温、中低盐度、低密度流体。碳、氧、硫和铅同位素特征分析表明成矿流体来源于深部。多日茸铅锌多金属矿床大体经历了四大形成过程,为浅成低温低盐低密度铅锌多金属矿床。     

A sand production prediction model for weak sandstone reservoir in Kazakhstan

Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.Accurate sand volume estimation is,however,still a challenging issue,especially for reservoirs in weak formations.The weak reservoirs containing viscous or heavy oil are mainly discovered in shallow depths in Kazakhstan,with moderate temperature and pressure.Many prediction models developed for open-hole completions where the reservoir materials usually possess certain strength are not applicable for the local reservoirs where the materials are significantly weaker even if casing is used to support the wellbore with oil produced through the perforation tunnels.In this context,a prediction model was proposed where the volume of the produced sand was estimated as the volume of the plastic zone of the failed materials surrounding the perforation tunnels.The model assumes an evolving truncated conical shape for the damage zone and takes into account stress distributions and shear failure in this zone.Then,the proposed model was used to estimate sand volumes in 20 wells during oil production with sequential increase of flow rates.The predictions match well with the measured sand volumes in a local oil field.Finally,a sensitivity analysis was conducted on the model performance.It shows that the permeability of the plastic zone was the most significant controlling factor in the prediction results.     

水力梯度对黏土渗透性影响的试验研究

渗透性是土体的重要工程性质之一,其受孔隙率、颗粒粒径及流体性质等诸多因素影响,但通常认为与水力梯度无关。现采用研制的刚性壁固结渗透装置,对经不同固结压力固结的黏土试样,进行先逐级施加水压、后逐级卸除水压条件下的固结和渗透试验。试验结果表明,水压加载时,受渗透力的影响,孔隙比和渗透系数均随水力梯度增大而减小,理论分析验证了递增水力梯度下渗透系数测试值变化趋势的合理性。水压卸载时,孔隙比不变,但渗透系数随水力梯度减小而继续减小,主要与颗粒堵塞和弱结合水相关,水力梯度较大时弱结合水处于流动状态,水力梯度递减后,弱结合水处于黏滞状态,孔隙导水能力下降,渗透系数降低,基于试验数据的线性拟合式显示降幅可达初始值的一半。     

含夹层盐岩储气库气体渗透规律研究

 盐岩储气库气体密封性能是储气库的一项重要技术和安全指标,层状盐岩储气库极可能会使天然气沿着岩层逃逸,造成天然气的外部渗漏。含软弱夹层盐岩储气库的气体渗透机制十分复杂,含软弱夹层的渗流力学模型与数值计算方法是解决评估储气库气体渗透范围的关键。考虑夹层与盐岩层之间存在层面,假设软弱夹层和盐岩为多孔介质,建立了等效边界气体渗流模型,该模型既克服了等效介质模型不能正确反映层理面渗流问题,又克服了双孔双渗裂隙介质模型计算量大的缺点。结合金坛储气库建设,数值仿真了储气库在注–采气不同循环压力作用下5 a内围岩气体压力分布;研究了软弱夹层与盐岩的层理面渗透系数、采气速率和腔体群不同时注–采气等工况对储库围岩气体压力分布的影响。研究结果表明：层理面渗透系数对储气库压力分布有着至关重要的影响,溶腔群的采气速率和注–采方法对相邻矿柱的气体压力分布影响明显。研究结果为含夹层废弃盐腔储气库的设计和合理注采参数的确定提供了科学依据。     

Single fractures under normal stress: The relation between fracture specific stiffness and fluid flow

Fracture specific stiffness and fluid flow through a single fracture under normal stress are implicitly related through the geometry of the void space and contact area that comprise the fracture. Data from thirteen different rock samples, each containing a single fracture, show that relationships between fracture specific stiffness and fluid flow through a fracture fall into two general classes of behavior. Fractures either fall on a loosely-defined universal curve relating fluid flow to fracture specific stiffness, or else the flow is weakly dependent on fracture specific stiffness. The second relationship shows that flow decreases slowly with increasing fracture specific stiffness. The first relationship shows that flow decreases rapidly for increases in fracture specific stiffness. To understand this behavior, computer simulations on simulated single fractures were performed to calculate fluid flow, fracture displacement, and fracture specific stiffness as a function of normal stress. Simulated fractures with spatially correlated and uncorrelated aperture distributions were studied. Fractures with spatially uncorrelated aperture distributions tend to exhibit a weak dependence of fluid flow on fracture specific stiffness because these fractures tend to have multiple connected paths across the sample which can support flow with uniformly distributed contact area. Thus an increment in stress will increase the stiffness of the fracture without greatly reducing the amount of fluid flow. On the other hand, fractures with spatially correlated aperture distributions tend to belong to the universal relationship because correlated fractures tend to have only one or two dominant flow paths and the contact area is limited to a few regions resulting in a compliant fracture. Thus an increment in stress on a spatially correlated fracture will result in an increase in stiffness and rapid decrease in fluid flow. These spatial correlations in fracture void geometry can be differentiated in the laboratory based on the observed fracture specific stiffness–fluid flow relationship for a single fracture under normal loading.     

低渗砂岩储层渗透率有效应力定律试验研究

 试验设计多个回路,各个回路的孔隙流体压力不同,每一回路在孔隙流体压力不变,增加和降低围压方式下进行。试验过程中采用稳态法测定不同围压和孔隙流体压力下的岩芯渗透率,并用响应面法对试验结果进行处理分析。结果表明,有效应力系数a 随围压和孔隙流体压力的变化而变化。当围压很大时,试验研究得到的有效应力系数很小,这与过去试验研究的结果差别很大。最后用有效应力系数a = 1.0和本次试验获取的有效应力系数对低渗砂岩岩样进行应力敏感性评价。用有效应力系数a = 1.0评价的结果是储层存在强应力敏感,而用本次试验获取的有效应力系数的评价结果是储层表现为弱应力敏感性。     

Particle–Fluid–Structure Interaction for Debris Flow Impact on Flexible Barriers

Flexible barriers are increasingly used for the protection from debris flow in mountainous terrain due to their low cost and environmental impact. However, the development of a numerical tool for the rational design of such structures is still a challenge. In this work, a hybrid computational framework is presented, using a total Lagrangian formulation of the finite element method to represent a flexible barrier. The actions exerted on the structure by a debris flow are obtained from simultaneous simulations of the flow of a fluid‐grain mixture, using two conveniently coupled solvers: the discrete element method governs the motion of the grains, while the free‐surface non‐Newtonian fluid phase is solved using the lattice Boltzmann method. Simulations on realistic geometries show the dependence of the momentum transfer on the barrier on the composition of the debris flow, challenging typical assumptions made during the design process today. In particular, we demonstrate that both grains and fluid contribute in a nonnegligible way to the momentum transfer. Moreover, we show how the flexibility of the barrier reduces its vulnerability to structural collapse, and how the stress is distributed on its fabric, highlighting potential weak points.