Comparison of laboratory-scale solute transport visualization experiments with numerical simulation using cross-bedded sandstone   总被引：1，自引：0，他引：1  

Katherine A. Klise  Vincent C. Tidwell  Sean A. McKenna   《Advances in water resources》2008,31(12):1731-1741

Using a slab of Massillon Sandstone, laboratory-scale solute tracer experiments were carried out to test numerical simulations using the Advection–Dispersion Equation (ADE). While studies of a similar nature exist, our work differs in that we combine: (1) experimentation in naturally complex geologic media, (2) X-ray absorption imaging to visualize and quantify two-dimensional solute transport, (3) high resolution transport property characterization, with (4) numerical simulation. The simulations use permeability, porosity, and solute concentration measured to sub-centimeter resolution. While bulk breakthrough curve characteristics were adequately matched, large discrepancies exist between the experimental and simulated solute concentration fields. Investigation of potential experimental errors suggests that the failure to fit solute concentration fields may lie in loss of intricate connectivity within the cross-bedded sandstone occurring at scales finer than our property characterization measurements (i.e., sub-centimeter).  相似文献   

Application of synchrosqueezed wavelet transforms to estimate the reservoir fluid mobility          下载免费PDF全文

Ya‐Juan Xue  Jun‐Xing Cao  Gu‐Lan Zhang  Guang‐Hui Cheng  Hui Chen 《Geophysical Prospecting》2018,66(7):1358-1371

This paper presents a new methodology for estimating reservoir fluid mobility using synchrosqueezed wavelet transforms. Synchrosqueezed wavelet transforms, which adopts a reassignment method, can improve the temporal and spatial resolutions of conventional time‐frequency transforms. The synchrosqueezed wavelet transforms‐based fluid mobility estimation requires the favourable selection of sensitive low‐frequency segment and more accurate estimation of the change rate of the low frequency segment in the spectrum. The least‐squares fitting method is employed in the synchrosqueezed wavelet transforms‐based fluid mobility estimation for improving the precision of the estimation of change rate of the low‐frequency segment in the spectrum. We validate our approach with a model test. Two field examples are used to illustrate that the fluid mobility estimation using the synchrosqueezed wavelet transforms‐based method gives a better reflection of fluid storage space and monitors hydrocarbon‐saturated reservoirs well.  相似文献   

A laboratory study of Equotip surface hardness measurements on a range of sandstones: What influences the values and what do they mean?     

Julie Desarnaud  Kyoko Kiriyama  Beril Bicer Simsir  Katrin Wilhelm  Heather Viles 《地球表面变化过程与地形》2019,44(7):1419-1429

The Equotip rebound tester is a simple, non-destructive technique to measure the surface hardness of materials. Having a low impact energy gives the Equotip advantages over the commonly used Schmidt Hammer on weathered rock and stone. In this study we have investigated the influence of different parameters (sample size, moisture content and surface roughness) on the surface hardness values obtained from freshly cut blocks of four types of sandstone. In a series of laboratory experiments both Single Impacts (SIM) and Repeat Impacts (RIM) methods have been used with C and D probes (which have different impact energies). Our results show that whilst sample size is of great importance we find that smaller samples can be reliably evaluated than previously reported. Moisture contents are also found to exert a more important influence on both SIM and RIM results than previously thought, with up to 26% lower hardness values recorded on saturated vs dry sandstone. Conversely, we find that surface roughness (over Sz values of 100 to 800 microns) does not have a significant impact on SIM measurements collected using the D probe. Both SIM and RIM data are found to be good proxies for compressive strength and open porosity, with SIM data collected with the C probe showing the best fits. Data collected using 3D microscopy helps visualize and quantify the small impact marks created by the Equotip and confirms that these are much reduced when using the C vs D probe. The results highlight the benefits of the Equotip to studies of the nature and deterioration of sandstone, the need for careful evaluation of any confounding factors which might influence the values obtained, and illustrate the different advantages of C and D probes. © 2019 John Wiley & Sons, Ltd.  相似文献   

Enigma variations: the stratigraphy,provenance, palaeoseismicity and depositional history of the Lower Old Red Sandstone Cosheston Group,south Pembrokeshire,Wales     

Richard G. Thomas  Brian P. J. Williams  Lance B. Morrissey  William J. Barclay  Keith C. Allen 《Geological Journal》2006,41(5):481-536

The Lower Devonian (Lochkovian‐Emsian) Cosheston Group of south Pembrokeshire is one of the most enigmatic units of the Old Red Sandstone of Wales. It consists of a predominantly green, exceptionally thick succession (up to 1.8 km) within the red c. 3 km‐thick fill of the Anglo‐Welsh Basin, but occupies a very small area (27 km²). Four formations—Llanstadwell (LLF), Mill Bay (MBF), Lawrenny Cliff (LCF) and New Shipping (NSF)—group into lower (LLF + MBF) and upper (LCF + NSF) units on stratigraphical and sedimentological criteria. Two palynostratigraphic associations (Hobbs Point and Burton Cliff) are recognised in the LLF. Overall, the Cosheston succession comprises a fluvial, coarsening‐upward megasequence, mostly arranged in fining‐upward rhythms. It is interpreted as the fill of an east‐west graben bounded by faults to the north and south of the Benton and Ritec faults, respectively. Both ‘lower Cosheston’ formations were deposited by east‐flowing, axial river systems draining a southern Irish Sea landmass. Drainage reversal, early in the deposition of the LCF, resulted in ‘upper Cosheston’ lateral, SW‐flowing rivers which carried predominantly second‐ and multi‐cycle detritus. The ‘lower Cosheston’ is characterized by an abundance of soft‐sediment deformation structures, probably seismically triggered by movements along the graben's northern bounding fault. A minimum average (≥ mesoseismic) earthquake recurrence interval of c. 4000 yr is estimated for the MBF. This and the correlative Senni Formation of south‐central Wales form a regionally extensive green‐bed development that represents a pluvial climatic interval. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

丹霞地貌砂岩的微观化学风化作用电子探针研究   总被引：2，自引：0，他引：2  

郭国林  郭福生  刘晓东  严兆彬  杨志 《中国岩溶》2006,25(2):172-176

利用偏光显微镜观察、电子探针分析等手段对江西龙虎山丹霞地貌崖壁砂岩的微观化学风化作用的发展过程进行了研究,重点观测黑云母蛭石化以及长石黏土化过程中矿物组分的变化,进而探讨丹霞地貌砂岩的微观化学风化作用机理。在微观化学风化下,强风化层胶结物中的方解石迅速分解流失,从而导致黑云母大量发生蛭石化和铁的氧化物在矿物边部富集;长石则大量发生黏土化而使高岭石、石英等矿物富集。研究表明丹霞地貌砂岩在微观化学风化作用下矿物分解以及新矿物的形成都破坏原来岩石中的力学平衡,因而风化作用在宏观上表现为岩面片状剥离和重力崩塌,据此推断更大尺度的风化作用可能与岩石中矿物的微观化学风化作用存在着密切联系,是微观化学风化作用长期累积后在宏观上的综合表现。   相似文献   

The Ridgeway Conglomerate Formation of SW Wales,and its implications. The end of the Lower Old Red Sandstone?     

Robert D. Hillier  Brian P. J. Williams 《Geological Journal》2007,42(1):55-83

The Devonian Old Red Sandstone Ridgeway Conglomerate Formation crops out in Pembrokeshire, SW Wales. It was deposited as part of a dryland alluvial fan, axial fluvial valley deposystem. It conformably overlies the mid Lochkovian Freshwater West Formation and probably predates deposition of the Lower Cosheston Group Mill Bay Formation indicating an Early Devonian (latest Lochkovian to earliest Pragian) age, rather than a Middle Devonian age as suggested by previous workers. It therefore represents the youngest preserved formation of the Milford Haven Group south of the Ritec Fault. The Formation thickens drastically into the Ritec Fault, indicating its control on sedimentation. The half‐graben topography initiated deposition of a hangingwall alluvial fan that was sourced from a southerly Lower Palaeozoic/Precambrian provenance within the present‐day Bristol Channel. The Formation is heterolithic in nature, with deposits on the fan reflecting a mixture of processes. Conglomerates were deposited primarily by laterally extensive sheetfloods, and as bars in low‐relief, laterally accreted channels. Sandstones were also predominantly deposited by sheetfloods. Gritty mudrocks in comparison demonstrate deposition by cohesive debris flows. The fan prograded northward and interfingered with a low‐gradient, high‐sinuosity fluvial channel system dominated by inclined and non‐inclined heterolithic stratification. Thinly laminated mudstone and sandstone interbeds were deposited in ephemeral fan‐toe and axial valley lakes that may have developed during sub‐humid climatic episodes. The lacustrine heterolithic association has associated matgrounds and possible ‘algal roll‐up’ structures. Calcretized peetee structures and root traces comprise a lake margin calcrete association. Fan gravels prograded into the axial fluvial valley during periods of increased sediment flux that may represent semi‐arid conditions and/or episodes of tectonic activity. Calcretes of varying development were established in both the fan and axial valley zones. Calcretes with lower stages of development are more proximal to the Ritec Fault reflecting decreased soil residence times and high deposition rates within the axial valley. More strongly developed soil profiles on the fan may indicate sequence boundaries associated with low sediment flux, or increased soil residence time due to active fan‐channel migration (the pedofacies concept). Groundwater calcretes have sharp‐based and layer‐bound calcrete profiles. Gully‐bed cements are locally developed within the fan gravels. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

鲁北深部砂岩热储开发地质环境变形效应研究          下载免费PDF全文

冯克印  贾超  丁朋朋  魏茂杰  王明珠  韩建江 《山东国土资源》2023,39(3):51-56

山东省深部砂岩热储资源丰富,热储开发利用对区域经济社会发展具有重要促进作用。但如果不注重深部热储的适度、有序开发,超出其临界量后可能会引发区域地面沉降等不良地质环境问题,因而,研究深部砂岩热储开发引发的地质环境变形问题意义重大。本文针对山东省鲁北典型深部砂岩热储区热储开采的地质环境影响问题进行深入研究,确定了开采量、开采层位等因素导致的热储层沉降量,分析了热储层沉降对该区地面总沉降的贡献。对深入认识鲁北地区深部砂岩热储的地质环境效应,合理开发深部热储资源提供借鉴与依据。  相似文献   

冻融循环作用下砂岩蠕变特性及损伤模型研究     

陈国庆  万亿  裴本灿  米冠宇 《工程地质学报》2020,28(1):19-28

青藏高原高寒地区岩体长期稳定性受冻融作用影响显著,有必要开展冻融岩石的时效性特征研究。为探讨砂岩在冻融循环作用下的蠕变劣化特性,基于不同冻融循环次数后石英砂岩及红砂岩单轴蠕变试验结果,深入分析了冻融循环对砂岩各蠕变阶段的影响特征。研究表明,在非屈服应力条件下,试样在衰减蠕变阶段的蠕变时长随着冻融循环次数的增加而明显减小,对应蠕变量及蠕变速率增大;在屈服应力条件下,试样进入加速蠕变阶段的应力阈值随着冻融循环次数的增加而逐渐降低,对应从稳定蠕变到加速破坏所经历的时间更短,破坏时累计的应变增量更大;在长期荷载作用下,试样的宏观破裂形态随循环次数的增加逐步由单一斜剪切破坏模式向共轭断面拉剪复合型破坏模式演化。根据试验结果,提出了具有冻融与长期受荷劣化特征的非定常性黏弹性系数损伤演化方程,将其引入西原模型构建了考虑冻融损伤的砂岩蠕变本构模型。利用冻融后红砂岩蠕变试验数据对模型进行了参数辨识与比较分析,验证了模型的正确性及适用性。通过对模型参数进行拟合分析,揭示了黏弹性冻融损伤系数随冻融循环次数的变化规律,表明了长期受荷损伤参数具有控制加速蠕变幅度的重要作用。研究结果对于高寒山区岩体长期稳定性评价具有一定意义。  相似文献   

Assessment of tafoni distribution and environmental factors on a sandstone djinn block above Petra,Jordan     

《Applied geography (Sevenoaks, England)》2013

Through the measurement of tafoni dimensions on an isolated, and unrecorded ‘djinn block’ in Petra's Ordovician Disi Sandstone, minimum surface recession were prevalent on eastern and western faces ranging from 10 to 127 mm/millennia. Moderate tafoni development was identified on northern aspects ranging from 105 to 110 mm/millennia. While on southern vertical faces, the greatest development ranged from 120 to 220 mm/millennia. Solar flux was correlated to the measured tafoni cell dimensions and revealed a minimal recession rate (and depth) of approximately 10–45 mm/millennia above which northern influences increased deterioration ‘moderately’ up to 110 mm/millennia, and southern influences had the greatest exacerbating effect with a maximum recessional rate of 220 mm/millennia – producing the greatest recession of nearly one inch (22 mm) each century. It is speculated that weathering accelerated on shaded (northern) faces through more frequent and longer spans of wetting and drying cycles, in addition to the effects of lichen and cyanobacteria overgrowth. While on regularly sunlit surfaces (southern), increased solar flux (up to ∼3000 MJ/m²/year) accelerated deterioration though more rapid, and extreme heating and cooling cycles. As rarely documented, tafoni on eastern faces were the smallest, and they were only slightly larger on western faces. Slightly increased heating from afternoon temperatures, in tandem with the incidence of frontal precipitation is attributed to the only slightly larger tafoni found on western faces (than on eastern aspects).  相似文献   

回灌水温对砂岩热储回灌效果的影响分析——以德州市地热田馆陶组热储为例     

张平平  王秀芹 《山东国土资源》2015,31(6)

根据砂岩孔隙型热储地热流体回灌试验中不同尾水温度与回灌量、回灌水位之间的关系,研究了相同回灌量条件下尾水温度对回灌效果的影响,并通过消除回灌尾水温度对井筒存储效应的影响,将回灌时水位升幅的观测值校正为同一温度下的真实水位升幅,从而对不同温度尾水回灌的渗透性能进行了分析。  相似文献