PASSIVE PRESSURE DETERMINATION BY METHOD OF SLICES     

Jyant Kumar  Kanakapura S. Subba Rao 《国际地质力学数值与分析法杂志》1997,21(5):337-345

A method of slices satisfying all the conditions of statical equilibrium has been developed to deal with the problem of determination of passive earth pressure over a retaining wall in sand. A method similar to that of Morgenstern and Price, which was used to solve the stability of slopes, has been followed. The earth pressure coefficients with the proposed methodology have been computed for a vertical retaining wall for both positive and negative wall friction angle. Also examined is the variation of the interslice shear force between the retaining wall and the Rankine Passive boundary. Due to complete satisfaction of the equilibrium conditions, the method generates exactly the same earth pressure coefficients as computed by using Terzaghi's overall limit equilibrium approach. © 1997 by John Wiley & Sons, Ltd.  相似文献   

致密砂岩气藏裂隙-孔隙型弹性岩石物理模板研究:以川西坳陷A区为例     

何润发  巴晶  陈天胜  张超  庞孟强  余村  马汝鹏 《地球物理学进展》2020,(1):116-123

相对于常规砂岩,致密砂岩在岩石物理性质、力学性质等方面具有明显差异,并呈现出很强的非均质性.岩石物理模型能将储层参数与地震特性信息联系起来,因此可以作为致密砂岩储层参数与地震特性信息转换的桥梁.常规的岩石物理模型通常只考虑单一因素(例如非均匀性,单一孔隙,单一尺度等),建立的岩石物理模板并不适用于致密砂岩.本文针对高饱和气、微裂隙发育、非均质性强的致密砂岩储层,利用Voigt-Reuss-Hill模型计算混合矿物的弹性模量,采用微分等效介质(DEM)模型描述含裂隙、孔隙岩石的骨架弹性模量,基于Biot-Rayleigh波动方程构建了岩石物理弹性模板,给出了致密砂岩储层弹性参数与物性的关系.基于测井数据和实验数据对岩石物理弹性模板进行校正,并将校正后的岩石物理弹性模板结合叠前地震资料应用于川西地区储层孔隙度与裂隙含量预测.结果显示,反演裂隙含量、孔隙度与储层试气报告、测井孔隙度基本吻合,表明该模板能够较合理地应用于致密砂岩储层孔隙度及裂隙含量解释中.  相似文献   

Fundamental yet simplified model for liquefaction instability     

Chandra S. Desai  Innjoon Park  Changming Shao 《国际地质力学数值与分析法杂志》1998,22(9):721-748

A fundamental procedure is proposed for the identification of liquefaction in saturated soils based on the instability in the material's microstructure. The disturbed state concept (DSC) provides a unified constitutive model for the characterization of entire stress–strain behaviour under cyclic loading, and the values of disturbance at threshold states in the deforming microstructure provides the basis for the identification of liquefaction. The procedure is verified with respect to laboratory behaviour of two sands, saturated Ottawa and Reid Bedford. A mathematical analysis of the DSC constitutive matrix is also performed. Procedures for the application of the DSC for simplified analysis and design, and in finite element procedures are presented. It is believed that the proposed model can provide a fundamental yet simplified procedure for liquefaction analysis, and as a result, it is considered to be an improvement over the available empirical and energy-based procedures. © 1998 John Wiley & Sons, Ltd.  相似文献   

松辽盆地梨树断陷致密气储层特征研究     

郭新军 《吉林地质》2020,39(1):1-4

梨树断陷下白垩统油气资源量大,勘探程度低,储层埋藏深,岩性致密,主要为中-细粒砂岩,孔隙类型以粒间孔、粒内溶孔、晶间微孔为主,铸模孔、粒缘缝和破裂缝次之。本文主要从岩石成分和孔隙类型两个方面分析影响储层储集性的因素,认为长石含量是决定储层物性的主要因素,浊沸石在成岩阶段早期被溶蚀形成有利孔隙,成岩晚期大量高岭石的出现说明生烃过程的排酸作用改变了成岩环境,方解石胶结物的溶蚀改变了储层的渗透性。  相似文献   

Effects of topography on lofting gravity flows: Implications for the deposition of deep-water massive sands     

Christopher J. Stevenson  Jeff Peakall 《Marine and Petroleum Geology》2010

Hyperpycnal flows are generated in the marine environment by sediment-laden fresh water discharge into the ocean. They frequently form at river mouths and are also generated in proximal ice-melting settings and are thought to be responsible for transporting a large proportion of suspended river sediment onto and off the continental shelf. Hyperpycnal flows are an example of gravity currents that display reversing buoyancy. This phenomenon is generated by the fresh water interstitial fluid being less dense than that of the ambient seawater. Thus after sufficient particles are sedimented the flow can become positively buoyant and loft, forming a rising plume. Here we present results from physical scale-modelling experiments of lofting gravity currents upon interaction with topography. Topography, in the form of a vertical obstacle, triggered a localised lofting zone on its upstream side. This lofting zone was maintained in a fixed position until the bulk density of the flow had reduced enough to allow lofting along its entire length. The obstructed lofting zone is associated with a sharp increase in deposit thickness. By inference these experimentally established lofting dynamics are applied to improve understanding of the potential for hyperpycnal flows to deposit deep-water massive sands. This study provides a depositional mechanism by which large volumes of sand can be deposited in the absence of traction and the fines removed, leaving thick deposits of structureless sand with a low percentage of mud. This conceptual model for the first time provides a framework by which the geometries of certain deep-water massive sands may be predicted within specific depositional and basinal settings. This is crucial to our understanding of massive sand deposits in modern and ancient turbiditic systems and in the commercial evaluation of hydrocarbon potential of such sedimentary successions.  相似文献   

Diagenetic and sedimentary controls on porosity in Lower Carboniferous fine-grained lithologies,Krechba field,Algeria: A petrological study of a caprock to a carbon capture site     

P.J. Armitage  R.H. Worden  D.R. Faulkner  A.C. Aplin  A.R. Butcher  J. Iliffe 《Marine and Petroleum Geology》2010

Fine-grained siliciclastic lithologies commonly act as sealing caprocks to both petroleum fields and host reservoirs for carbon capture (CO₂ sequestration) projects. Fine-grained lithologies are thus of great importance in controlling fluid flow and storage in the subsurface. However, fine-grained rocks are rarely characterised in terms of primary sedimentary characteristics, diagenesis and how these relate to their flow properties (i.e. sealing or caprock quality). Seventeen samples from Lower Carboniferous estuarine caprock to a gas field (also to be used as a carbon capture site), have been analysed using a range of petrological and petrophysical techniques. The rock unit that represents the caprock to this gas field was found to be predominantly silt grade with porosity values as low as 1.8%. In these rocks, caprock quality (porosity) is controlled by intrinsic and extrinsic factors linked to primary mineralogy and diagenetic processes. Depositional mineralogy was dominated by quartz, detrital mica, detrital clay (likely Fe-rich 7Å clay and illite–smectite) with minor feldspar and oxide phases. Diagenetic processes included compaction, minor feldspar dissolution and kaolinite growth and the more important processes of chlorite, siderite and quartz cementation, as well as the likely transformation of smectite into illite. Caprock quality is controlled by the primary quantity of illite-muscovite in the sediment and also by the localised extent of chlorite and quartz cementation. Deposition in an estuarine environment led to highly heterogeneous distribution of primary and diagenetic minerals, and thus caprock quality, between and within the samples.  相似文献   

Role of fluvial and structural processes in the formation of the Wahiba Sands, Oman: A remote sensing perspective   总被引：1，自引：0，他引：1  

C.A. Robinson  F. El-Baz  T.M. Kusky  M. Mainguet  F. Dumay  Z. Al Suleimani  A. Al Marjeby 《Journal of Arid Environments》2007,69(4):676-694

The Wahiba Sands in northeastern Oman are bordered on the north, south and west by highlands. Remote sensing data are used to characterize the region between 19–23.5°N and 56.5–60°E by mapping surface and near-surface drainage, faults and fractures and aeolian features. It is suggested that the sands were originally deposited with surface runoff from the principal wadis and fluvially reworked fault zones, which define the northeastern and southwestern margins. These fluvial processes resulted in the accumulation of the vast groundwater resources now stored there. During dry climates, wind became the principal modification regime and it began to sort and shape the sediments into the dune forms that characterize today's Wahiba region. The thickness of the sands reflects the depth of the basin in which they lie. The center of the basin is filled with the thickest sand (the High Sands) and contains the highest groundwater concentrations. Presently, aeolian reworking dominates in the Wahiba region, although the Low and the Peripheral Sands continue to experience some fluvial action from occasional, seasonal rainfall. Even though dry conditions dominate today, it is clear that similar to the Sahara of North Africa, the surface sands of the Wahiba basin are indicators of groundwater occurrence.  相似文献   

A 2‐D constitutive model for cyclic interface behaviour     

Giuseppe Mortara  Marc Boulon  Vito Nicola Ghionna 《国际地质力学数值与分析法杂志》2002,26(11):1071-1096

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砂砾性低渗气层水锁效应及减轻方法的试验研究   总被引：4，自引：0，他引：4  

张琰  崔迎春 《地质与勘探》2000,36(1):92-95

采用来自胜利油田的岩样,通过水锁效应对岩样渗透率影响的试验研究证实了水锁效应是导致砂砾性低渗气层损害的主要原因之一。然后对油田常用的表面活必地表面张力的测定,并在此基础上进行了优选,最后对用表面活性剂减轻岩样水锁效应的效果进行了评价试验。  相似文献   

Unconventional Energy Resources and Geospatial Information: 2006 Review   总被引：1，自引：1，他引：0  

American Association of Petroleum Geologists  Energy Minerals Division 《Natural Resources Research》2007,16(3):243-261

This article contains a brief summary of some of the 2006 annual committee reports presented to the Energy Minerals Division (EMD) of the American Association of Petroleum Geologists. The purpose of the reports is to advise EMD leadership and members of the current status of research and developments of energy resources (other than conventional oil and natural gas that typically occur in sandstone and carbonate rocks), energy economics, and geospatial information. This summary presented here by the EMD is a service to the general geologic community. Included in this summary are reviews of the current research and activities related to coal, coalbed methane, gas hydrates, gas shales, geospatial information technology related to energy resources, geothermal resources, oil sands, and uranium resources.

American Association of Petroleum Geologists, Energy Minerals DivisionEmail:

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