The Lower Paleozoic rock units in Egypt:An overview

Lower Paleozoic rocks are exposed in various regions of Egypt（south central Sinai,north Eastern Desert and southwest Western Desert）,in addition to occurring in the subsurface such as north Western Desert and the Gulf of Suez.The Lower Paleozoic rocks in Egypt include surface and subsurface rock units of formational status.The surface rock units are the Taba,Araba and Naqus formations. The subsurface rock units include the Shifa,Kohla and Basur formations. The Infracambrian Taba Formation has been discovered recently in the outcrops of the southeast central Sinai in the Taba-Ras El-Naqab area.It is missing and/or not recognized in the subsurface.The Taba Formation consists mainly of reddish brown,unfossiliferous gravelly fine-to medium-grained kaolinitic sandstones and subordinate horizons of paleosols.The Cambrian Araba Formation and its subsurface equivalent（the Shifa Formation） are essentially composed of reddish brown,line-grained laminated sandstone and siltstone with abundant Skolithos and Cruziana sp.In contrast,the Ordovician—Silurian Naqus Formation and its subsurface equivalents（the Kohla Formation and Basur Formation） are mainly composed of white,unfossiliferous,cross-bedded,medium-to coarse-grained sandstones with haphazardly distributed pebbles and cobbles.Sedimentological analysis indicates that the Araba Formation and its subsurface equivalent were deposited in a marginal-marine environment,whereas the Naqus Formation and its subsurface equivalents were laid down in a fluvio-glacial environment. Integrated stratigraphic and sedimentological studies of the Lower Paleozoic rocks permit reconstruction of the paleogeography of Egypt at that time.Egypt has been largely controlled since the Cambrian by the pre-existing structural framework of the pre-Phanerozoic basement rocks inherited from the Late Proterozoic Pan-African event.Additionally,sedimentation processes were controlled during Cambro-Ordovician times by tectonic movements,whereas glacio-eustatic control predominated during the Late Ordovician—Silurian Period.These studies suggest that most areas of Egypt were exposed lands with episodically transgression by epi-continental seas related to the paleo-Tethys.These lands formed a part of a stable subsiding shelf at the northern Gondwana margin.

A Comparison about Metamorphism among the Oldest-Rock Units from Orogenic Belts of Dabie,Eastern Qinling and Eastern Kunlun of Central Mountain Ranges,China

The Dabie orogen, Eastern Qinling orogen and Eastern Kunlun orogen are the major components of the Central Mountain Ranges of China and each has distinctively metamorphic processes in their oldest rock units. The Dabie orogen oldest rock units had experienced an intermediate-higher pressure, upper amphibolite to lower granulite facies metamorphism in the Indosinian intracontinental subduction collision event. The clockwise pt path, synchronous attainment of t max and p max and a segment of high slope retrograde path suggest a tectono driven rapid exhumation of the oldest rock units to upper middle crustal level following the end of the subduction collision process. The oldest rock units, also called Qinling Group, of Eastern Qinling Mountains suffered intensively collisional metamorphism at an immature plate tectonic framework during Jinningian movement about 1 000 Ma ago. The clockwise pt path with reach of t max following several hundreds of MPa decreasing from p max suggests that the denudation of the deeply burial rock units was due essentially to isostatic relaxation. During the Caledonian stage, the highly metamorphosed oldest rock units suffered from a high t thermal event in arc environment and superimposed by contact metamorphism. After thermal peaks, the rock units were exhumed in a short distance and cooled down isobarically. No regional metamorphism higher than upper greenschist facies condition since 300 Ma has been traced within exposed rocks in the eastern portion of Northern Qinling orogen. The oldest rock units in the Eastern Kunlun orogen were metamorphosed to upper amphibolite facies to lower granulite facies rocks early or during the Luliang movement (some 1 800 Ma ago). The high grade metamorphic rock units had a long resident time at the deep crustal level, and were exhumed to middle upper crustal level during the Caledonian to Hercynian tectonometamorphic events. Shallow erosion of the orogenic belt led to good preservation of the low pressure metamorphic belt.

Estimating Unconfined Compressive Strength of Sedimentary Rocks in United Arab Emirates from Point Load Strength Index

In this paper, three rock types including Sandstone, Mudstone, and Crystalline Gypsum were part of a laboratory study conducted to develop a dataset for predicting the unconfined compressive strength of UAE intact sedimentary rock specimens. Four hundred nineteen rock samples from various areas along the coastal region of the UAE were collected and tested for the development of this dataset and evaluation of models. From the statistical analysis of the data, regression equations were established among rock parameters and correlations were expressed and compared by the ones proposed in literature.

The inversion of density structure by graphic processing unit(GPU) and identification of igneous rocks in Xisha area

Organic reefs, the targets of deep-water petro- leum exploration, developed widely in Xisha area. However, there are concealed igneous rocks undersea, to which organic rocks have nearly equal wave impedance. So the igneous rocks have become interference for future explo- ration by having similar seismic reflection characteristics. Yet, the density and magnetism of organic reefs are very different from igneous rocks. It has obvious advantages to identify organic reefs and igneous rocks by gravity and magnetic data. At first, frequency decomposition was applied to the free-air gravity anomaly in Xisha area to obtain the 2D subdivision of the gravity anomaly and magnetic anomaly in the vertical direction. Thus, the dis- tribution of igneous rocks in the horizontal direction can be acquired according to high-frequency field, low-frequency field, and its physical properties. Then, 3D forward model- ing of gravitational field was carried out to establish the density model of this area by reference to physical properties of rocks based on former researches. Furthermore, 3D inversion of gravity anomaly by genetic algorithm method of the graphic processing unit （GPU） parallel processing in Xisha target area was applied, and 3D density structure of this area was obtained. By this way, we can confine the igneous rocks to the certain depth according to the density of the igneous rocks. The frequency decomposition and 3D inversion of gravity anomaly by genetic algorithm method of the GPU parallel processing proved to be a useful method for recognizing igneous rocks to its 3D geological position. So organic reefs and igneous rocks can be identified, which provide a prescient information for further exploration.

纵轴岩巷掘进机截割部故障分析

主要介绍了纵轴岩巷掘进机截割部的组成和工作原理。通过对截割部结构分析,结合现场经验,总结了一些常出现的故障现象,对其原因进行分析并提出应对措施,可以帮助维修人员快速判断和解决问题,也为截割部的设计提供依据。

An Integrated Rock Typing Approach for Unraveling the Reservoir Heterogeneity of Tight Sands in the Whicher Range Field of Perth Basin, Western Australia

Tight gas sands in Whicher Range Field of Perth Basin show large heterogeneity in reservoir characteristics and production behavior related to depositional and diagenetic features. Diagenetic events (compaction and cementation) have severely affected the pore system. In order to investigate the petrophysical characteristics, reservoir sandstone facies were correlated with core porosity and permeability and their equivalent well log responses to describe hydraulic flow units and electrofacies, respectively. Thus, very tight, tight, and sub-tight sands were differentiated. To reveal the relationship between pore system properties and depositional and diagenetic characteristics in each sand type, reservoir rock types were extracted. The identified reservoir rock types are in fact a reflection of internal reservoir heterogeneity related to pore system properties. All reservoir rock types are characterized by a compacted fabric and cemented framework. But distribution and dominance of diagenetic products in each of them depend on primary depositional composition and texture. The results show that reservoir rock typing based on three aspects of reservoir sandstones (depositional properties, diagenetic features and petrophysical characteristics) is a suitable technique for depiction of reservoir heterogeneity, recognition of reservoir units and identifying factors controlling reservoir quality of tight sandstones. This methodology can be used for the other tight reservoirs.

湿陷性黄土地区碎石排水系统砂岩碎石遇水软化试验研究

为研究延安湿陷性黄土地区进行的平山造地工程碎石排水系统中砂岩的遇水软化特性及其对工程施工稳定性的影响,采用WDW-600微机控制电子万能机对现场所取砂岩岩样开展了岩石单轴压缩试验和圆盘劈裂试验,测定烘干状态、天然状态、浸水饱和状态三种不同含水量的砂岩的强度及软化特性,结果表明:该地区砂岩遇水后会发生较为明显的强度软化,其中岩石抗压强度软化程度稍大,烘干样、天然样和饱和样平均抗压强度分别为14.54MPa、10.58MPa和7.70MPa,软化系数为0.53;烘干样、天然样和饱和样平均抗拉强度分别为1.43MPa、1.30MPa和0.83MPa。试验增强了对延安湿陷性黄土地区砂岩遇水软化力学性能的认识,对岩石遇水软化后排水系统承载性能计算和稳定性分析具有参考价值。

冻结砂岩爆破破岩的能量耗散特性

为探究冻结岩体的冲击力学性能,并提出寒区爆破开挖工程中合理的爆破炸药单耗,针对寒区典型分布的砂岩,采用室内分离式霍普金森压杆试验与理论分析相结合的方法,开展了冻结砂岩冲击力学性能及爆破破岩能量耗散特性研究。结果表明:(1)冻结状态砂岩的动态抗压强度和动态弹性模量相比常温状态整体有所提升,而应变峰值整体有所下降。对比静载与动载试验结果,相同物理参数下,砂岩的抗压强度差距不大,而动态弹性模量明显高于静态弹性模量。(2)常温状态砂岩和冻结状态砂岩试件的耗散能量均随含水率的增大而逐渐减低,且冻结状态砂岩的耗散能量高于常温状态。相比常温状态,冻结砂岩在含水率为0、0.25ω、0.50ω、0.75ω、1.00ω时,其耗散能量增幅分别为21.6%、64.9%、80.3%、78.2%、83.3%。(3)相同含水率下,冻结状态砂岩的炸药单耗均高于常温状态,在含水率为0、0.25ω、0.50ω、0.75ω、1.00ω时,冻结状态砂岩爆破炸药单耗相比常温状态分别增加20.4%、61.3%、60.0%、55.6%、66.7%。(4)将常温与冻结状态砂岩爆破炸药单耗数值进行拟合,得到不同状态砂岩爆破破岩的单耗修正模型,可为寒区爆破工程提供参考。

钻爆法隧道上台阶爆破炮孔装药量精细计算方法

目前隧道钻爆法施工技术日趋成熟,但炮孔装药量的精细计算仍缺乏可靠的经验或理论公式。基于利文斯顿爆破漏斗理论,考虑隧道上台阶爆破方案设计中的炮孔孔距、排距和倾角等因素,提出了倾斜与垂直炮孔负担爆破岩石体积的计算方法。考虑岩石坚固性系数、爆生临空面方向等因素的影响,建立了炸药单耗优化计算方法。最后,基于炮孔装药量经验体积计算公式,提出了隧道上台阶爆破炮孔装药量精细计算的方法。依托临沂至滕州高速公路寨山隧道开挖试验段,验证了炮孔装药量计算方法的可靠性,研究成果对指导隧道精细爆破具有重要意义。

深部硬岩钻探中孕镶金刚石钻头碎岩单元强化研究进展及建议

随着深部矿产资源的勘探开发与利用的不断发展,孔底环境更加复杂,孕镶金刚石钻头作为地质钻探的专用工具,复杂的深部硬岩地质环境对孕镶金刚石钻头性能也提出更高的要求。孕镶金刚石钻头的碎岩效率及寿命与其碎岩单元性能息息相关,本文对深部硬岩钻进中孕镶金刚石钻头的钻进磨损响应研究现状进行综述,目前研究还不够完善,仍需进一步开展微观深入分析,厘清响应机制。在此基础上,讨论了近年来碎岩单元的创新设计进展,重点从胎体内部结构强化及异形孕镶唇面结构等方面总结分析不同强化方式对切削单元强度、磨损量、钻进效率的影响,研究结果表明确实可以有效提高深部硬岩孕镶钻头的切削效率和工作寿命。从延寿增效的角度讨论了适用于深部硬岩钻进的孕镶金刚石钻头碎岩单元强化方向,为深部地质钻探用孕镶金刚石钻头的设计与制造提供参考。

新疆阿尔金山曼特里克一带阿尔金岩群的解体及重新厘定及找矿前景分析

阿尔金造山带地质情况复杂,各类岩石地层呈大小差异悬殊的构造岩片或岩块产出,岩石地层单位厘定争议已久。根据前人统计的资料及1∶5万区域地质矿产调查,对原划分于阿尔金岩群中,但岩石类型及其组合、变质程度、原岩建造特征和变质矿物组合等方面,与阿尔金岩群定义不符的岩石组合经过区域对比,结合测年数据,将其厘定为巴什库尔干岩群贝壳滩岩组,并分析其具有Cu、Mo找矿前景。

赣中地区早白垩系(燕山期)龙古山单元岩体高岭土深加工提纯试验

高岭土由长石、普通辉石等铝硅酸盐类矿物风化而成,主要成分为高岭石,用途广泛。试验以赣中地区早白垩系(燕山期)龙古山单元岩体的高岭土为研究对象,采用捣浆、螺旋分级、水力旋流器分级、磨矿、浮选、磁选、增白和酸浸等选矿工艺进行深加工提纯,得到能满足工业利用的高岭土、高纯石英砂、长石和云母等产品,从而推进高岭土的开发利用。

数字钻探随钻参数与岩石单轴抗压强度关系

针对常规的现场岩石单轴抗压强度测试方法周期长、成本高的问题,提出一种基于数字钻探测试岩石单轴抗压强度的方法。根据岩石钻进过程中的受力特点,基于能量分析法,推导了岩石单位切削能与随钻参数的关系式。同时,基于自主研发的多功能岩石钻探测试系统,开展了砂岩及不同强度砂浆试件等完整岩石的数字钻探试验,通过试验结果分析,建立了随钻参数与岩石单轴抗压强度的定量关系模型(DP-UCS模型),并对其进行了验证,结果表明:DP-UCS模型预测的单轴抗压强度与单轴压缩试验测定的单轴抗压强度的差异率平均值小于10%,证明了该模型的有效性。

苏北盆地闵北地区阜宁组一、二段火山岩的储集特征

苏北盆地金湖凹陷闵北地区火山岩储集空间主要有原生孔隙和次生孔隙两类 ,原生孔隙包括粒间孔、晶间孔、气孔及原生节理 ,是在火山岩堆积、成岩时形成的 ,原生孔隙多处于孤立分布的状态 ,并且又多被充填。次生孔隙包括粒内溶孔、溶蚀孔、缝、洞等 ,是火山岩成岩之后 ,因风化、淋滤、溶蚀及构造应力作用形成 ,次生孔隙能大大改善储集性能 ,尤其是构造节理 ,对孤立分布的原生孔隙起到了很好的连通作用。通过对火山岩孔、渗测井曲线分析对比发现 ,在剖面上 ,一个岩流单元的孔、渗值由下往上呈变大的趋势 ;岩流组的孔、渗变化特点与岩流单元一致或表现为这一规律的若干次重复 ;研究区东西向孔、渗值变化较大 ,南北向相对平稳。阜宁组一段的Ⅵ～Ⅺ及阜二段的Ⅲ岩流组储集性能较好。

塔河油田缝洞型油藏流动单元的定义和划分

目前,流动单元研究在砂岩油藏研究中已得到广泛应用,但对于缝洞型碳酸盐岩油藏来说,由于成岩后生作用、构造断裂作用、溶蚀作用等多种因素对储集空间的综合影响,使砂岩油藏的流动单元研究方法难以直接应用于缝洞型碳酸盐岩油藏。因此,针对塔河油田缝洞型碳酸盐岩地质特征,论证了该区碳酸盐岩储层渗流屏障的存在及其类型,探索性提出区别于砂岩油藏的缝洞型碳酸盐岩储层流动单元的综合研究方法,包括油藏压力趋势分析法和流体性质分析法等,并综合缝洞型储层的发育特征初步划分了该区的缝洞型碳酸盐岩流动单元。

破裂围岩锚固体变形破坏特征试验研究

为了进一步揭示破裂围岩锚固体的承载机制，在自主研制的真三轴物理模拟试验系统的基础上，采用反复加卸载围压的方法预制破裂岩体，加锚后进行继续加载试验，研究破裂围岩锚固体以及锚杆的变形破坏特征。研究发现，随着锚杆预紧力的增加，锚固体变形模量随之增加，全应力一应变曲线呈现双峰特征。在锚杆预紧力较小的情况下，破裂围岩内部滑移块体主要沿原有裂隙面滑移，二次破坏较少发生且裂隙发育位置比较集中。在锚杆预紧力较大的情况下，滑移块体会发生二次破坏，破裂围岩锚固体新生裂隙倾角高、数量多且分布均匀。锚固体变形过程中锚杆控制角在空间以及时间上不断发展变化：锚杆压缩区在空间上为向围岩深部开口的喇叭形，其深度为1～1．5倍托盘直径；随着锚固体压缩变形，锚杆压缩区会发生二次甚至多次破裂。锚杆控制角在压缩区初次破裂时为50°～64°，在压缩区多次破裂后最终稳定为34°～56°。锚杆在破裂面附近受到两侧滑移块体剪切错动作用下处于压、张、剪复杂应力状态，弯曲变形严重，这反过来使破裂面两侧滑移块体出现一定程度的错动分离。

高温高压条件下花岗岩切削破碎试验研究

为了达到最接近实际工程的试验效果,采用中国矿业大学的"20MN伺服控制高温高压岩体三轴试验机",设计了精确的加压和旋转系统,操作控制比较方便,测量数据准确。利用大尺寸(φ200mm×400mm)花岗岩试样和工程钻头(φ30mm的PDC钻头),使试验条件更加接近实际工程情况,开创了该类大试样试验的先河。通过正交试验研究花岗岩在高温高压状态下的切削破碎规律,得出以下结论:(1)高围压状态(100MPa)下,随着温度升高,花岗岩的可切削性逐渐增强,在超过一定的钻压时,切削速度随着温度的升高而明显增大,在755N钻压下,300℃的切削速度比室温时增大30%～50%;(2)高围压状态(100MPa)下,随着温度升高,单位破岩能耗明显降低,在钻压为755N时,300℃时的单位破岩能耗比室温时降低20%～30%;(3)在高温高压环境下,切削速度随着钻压或转速的增大而增大;单位破岩能耗随着转速的增大而增大,随着钻压的增大而减小,与室温无围压状态下的切削破碎规律基本一致;(4)由于花岗岩在此温压范围内属于渐进破坏,抗压强度下降缓慢,如果钻压太低则切削速度和单位破岩能耗受温度影响很小,为了在高温下取得对花岗岩的良好切削效果,钻压需要超过一定的值。

基于数字化施工的山区公路土石混合弃渣工程尺度参数测定方法研究

为了解决山区公路土石混合弃渣取样代表性和实验结果离散性问题并获取弃渣工程尺度参数。结合数字化施工过程获取弃渣总重量、堆填体积和极限直立高度,提出弃渣工程尺度容重、内摩擦角和黏聚力计算公式,组成山区公路土石混合弃渣工程尺度测定方法体系,并与传统有限尺寸和数量实验测定方法进行比较。研究结果表明:该方法紧密结合施工过程,不用进行额外的取样和实验,且参数取值偏小、稳定性评价结果具有一定保守特征,可以作为传统方法的有益补充。基于数字化施工的山区公路弃渣工程尺度参数测定方法,可以为动态设计、动态评估提供参数支持,也有助于动态施工、规划堆积、施工优化、施工风险管控。

岩石破裂过程的统计损伤模拟研究

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