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1.
Large-scale numerical simulation of groundwater flow and solute transport in discretely-fractured crystalline bedrock 总被引：1，自引：0，他引：1
A large-scale fluid flow and solute transport model was developed for the crystalline bedrock at Olkiluoto Island, Finland, which is considered as potential deep geological repository for spent nuclear fuel. Site characterization showed that the main flow pathways in the low-permeability crystalline bedrock on the island are 13 subhorizontal fracture zones. Compared to other sites investigated in the context of deep disposal of spent nuclear fuel, most deep boreholes drilled at Olkiluoto are not packed-off but are instead left open. These open boreholes intersect the main fracture zones and create hydraulic connections between them, thus modifying groundwater flow. The combined impact of fracture zones and open boreholes on groundwater flow is simulated at the scale of the island. The modeling approach couples a geomodel that represents the fracture zones and boreholes with a numerical model that simulates fluid flow and solute transport. The geometry of the fracture zones that are intersected by boreholes is complex, and the 3D geomodel was therefore constructed with a tetrahedral mesh. The geomodel was imported into the numerical model to simulate a pumping test conducted on Olkiluoto Island. The pumping test simulation demonstrates that fracture-borehole intersections must be accurately discretized, because they strongly control groundwater flow. The tetrahedral mesh provides an accurate representation of these intersections. The calibrated flow model was then used for illustrative scenarios of radionuclide migration to show the impact of fracture zones on solute transport once the boreholes were backfilled. These mass transport simulations constitute base cases for future predictive analyses and sensitivity studies, since they represent key processes to take into consideration for repository performance assessment. 相似文献
2.
为了查明乌鲁木齐西山—碗窑沟断裂带地应力分布特征, 在研究区20 km×20 km的范围内布置12个基岩应力钻孔,采用水压致裂地应力测量技术进行了基岩原地应力测量;共布置了2条观测剖面,第一剖面是沿断层走向布置了7个钻孔,第二剖面在垂直断层走向布置了6个钻孔(与第一剖面共用1个钻孔).根据实测的地应力资料,断层附近最大水平主压应力方向为NE—NEE向,与区域构造应力SN—NNE向主压方向有一些差异,说明受断层活动影响,断层附近的应力状态与区域应力场明显不同.利用地应力实测资料,研究了断层的活动性,在测量深度域内水平和垂直应力的关系为σH＞σh＞σv,该应力状态有利于逆断层活动,与地质资料反映的以逆断层活动为主基本一致.利用库仑摩擦滑动准则,摩擦系数取0.6~1.0分析,断层附近的现今地应力状态达到或超过产生逆断层摩擦滑动的临界值,表明测区现今构造应力有利于逆断层活动. 相似文献
3.
Slopes of an airborne electromagnetic resistivity model interpolated jointly with borehole data for 3D geological modelling 
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下载免费PDF全文 P.‐A. Reninger G. Martelet J. Perrin J. Deparis Y. Chen 《Geophysical Prospecting》2017,65(4):1085-1096
We investigate a novel way to introduce resistivity models deriving from airborne electromagnetic surveys into regional geological modelling. Standard geometrical geological modelling can be strengthened using geophysical data. Here, we propose to extract information contained in a resistivity model in the form of local slopes that constrain the modelling of geological interfaces. The proposed method is illustrated on an airborne electromagnetic survey conducted in the region of Courtenay in France. First, a resistivity contrast corresponding to the clay/chalk interface was interpreted confronting the electromagnetic soundings to boreholes. Slopes were then sampled on this geophysical model and jointly interpolated with the clay/chalk interface documented in boreholes using an implicit 3D potential‐field method. In order to evaluate this new joint geophysical–geological model, its accuracy was compared with that of both pure geological and pure geophysical models for various borehole configurations. The proposed joint modelling yields the most accurate clay/chalk interface whatever the number and location of boreholes taken into account for modelling and validation. Compared with standard geological modelling, the approach introduces in between boreholes geometrical information derived from geophysical results. Compared with conventional resistivity interpretation of the geophysical model, it reduces drift effects and honours the boreholes. The method therefore improves what is commonly obtained with geological or geophysical data separately, making it very attractive for robust 3D geological modelling of the subsurface. 相似文献
4.
Identifying flows into, out of, and across boreholes is important for characterizing aquifers, determining the depth at which water enters boreholes, and determining the locations and rates of outflow. This study demonstrates how Single Borehole Dilution Tests (SBDTs) carried out under natural head conditions provide a simple and cheap method of identifying vertical flow within boreholes and determining the location of in‐flowing, out‐flowing, and cross‐flowing fractures. Computer simulations were used to investigate the patterns in tracer profiles that arise from different combinations of flows. Field tracer tests were carried out using emplacements of a saline tracer throughout the saturated length of boreholes and also point emplacements at specific horizons. Results demonstrated that SBDTs can be used to identify flowing fractures at the top and bottom of sections of vertical flow, where there is a change in vertical flow rate within a borehole, and also where there are consistent decreases in tracer concentration at a particular depth. The technique enables identification of fractures that might be undetected by temperature and electrical conductance logging, and is a simple field test that can be carried out without pumping the borehole. 相似文献
5.
V. Yu. Timofeev D. G. Ardyukov E. V. Boiko A. V. Timofeev A. V. Yaroshevich P. Yu. Gornov 《Izvestiya Physics of the Solid Earth》2012,48(7-8):640-652
Variations in the water level in boreholes emerge in response to tidal, baric, and tectonic forcing. We analyze the data on atmospheric pressure and water level recorded in the boreholes located in the mid-latitude Eurasia (45°?C55°N) from Western Europe (Belgium, Uccle), Siberia (coastal area of Lake Baikal, Talaya River) to Far Eastern Russia (the Bychikha borehole near Khabarovsk and the boreholes on the Kamchatka Peninsula and Kurils). The response of the water level in a borehole to periodic tidal and baric impacts is investigated. In this case, water level variations reflect areal (lateral) and vertical deformations, which allows estimating the elastic moduli and porosity of the confined aquifer in a static model. Measurements in the boreholes drilled in the fractured solid rock enable determining the geometric parameters of the fractures. The possibility to apply the method for evaluating tectonic deformations is discussed. Application of tidal coefficients of boreholes for determining the coseismic deformation is demonstrated by the example of the Kultuk earthquake (Lake Baikal, August 27, 2008, M = 6.3). 相似文献
6.
Allen M. Shapiro 《Ground Water Monitoring & Remediation》2002,22(3):151-164
Collecting water samples for geochemical analyses in open bedrock boreholes or in discrete intervals of boreholes intersected by multiple fractures is likely to yield ambiguous results for ground water chemistry because of the variability in the transmissivity, storativity, and hydraulic head of fractures intersecting the borehole. Interpreting chemical analyses of water samples collected in bedrock boreholes requires an understanding of the hydraulic conditions in the borehole under the ambient flow regime in the aquifer as well as during sampling. Pumping in open boreholes, regardless of the pumping rate and the location of the pump intake, first draws water from the borehole and then from fractures intersecting the borehole. The time at which the volumetric rate of water entering the borehole from fractures is approximately equal to the pumping rate can be identified by monitoring the logarithm of drawdown in the borehole as a function of the logarithm of time. Mixing of water entering the borehole from fractures with water in the borehole must be considered in estimating the time at which the pump discharge is representative of aquifer water. In boreholes intersected by multiple fractures, after the contribution from the borehole volume has diminished, the contribution of fractures to the pump discharge will be weighted according to their transmissivity, regardless of the location of the pump intake. This results in a flux-averaged concentration in the pump discharge that is biased by the chemical signature of those fractures with the highest transmissivity. Under conditions where the hydraulic head of fractures varies over the length of the borehole, open boreholes will be subject to ambient flow in the water column in the borehole. In some instances, the magnitude of the ambient flow may be similar to the designated pumping rate for collecting water samples for geochemical analyses. Under such conditions, the contributions to the pump discharge from individual fractures will be a function not only of the transmissivity of the fractures, but also of the distribution of hydraulic head in fractures intersecting the borehole. To reduce or eliminate the deleterious effects of conducting geochemical sampling in open boreholes, a straddle-packer apparatus that isolates a single fracture or a series of closely spaced fractures is recommended. It is also recommended that open boreholes be permanently outfitted with borehole packers or borehole liners in instances where maintaining the hydraulic and chemical stratification in the aquifer is of importance. In a field example, a comparison of results from sampling in an open borehole and in discrete intervals of the same borehole showed dramatic differences in the concentrations of chemical constituents in the water samples, even though chemical field parameters stabilized prior to both open borehole and discrete interval sampling. 相似文献
7.
为获得矿山深部开采和设计所需要的地应力基础资料,中国地质科学院地质力学研究所于2012—2013年在冀东地区滦县—乐亭大断裂附近开展了3个钻孔水压致裂的应力测量工作,钻孔孔深为500—1 000 m.地应力测量结果初步揭示了研究区地壳浅表层现今地应力的分布规律.实测结果表明:现今研究区域应力场优势方向为NW70°;3个测点的最大剪切应力与平均应力的比值um范围为0.24—0.48,平均值分别为0.30,0.40和0.30,均未达到地壳应力摩擦极限状态(um=0.6)的水平,而唐山大地震后不久研究区浅层获得的um则较大,个别点大于0.6,平均值为0.44,表明唐山大地震后研究区应力积累程度较低,应力释放较为充分;依据断层摩擦准则及拜尔利定律可知,研究区发生较大地震活动的危险性较低. 相似文献
8.
Haim Gvirtzman 《Ground Water Monitoring & Remediation》2013,33(3):101-110
This study deals with the reliability of monitoring the transition zone between fresh and saline waters in coastal aquifers, considering the effect of tides in long‐perforated boreholes. Electric conductivity (EC) fluctuations in the coastal aquifer of Israel, as measured in long‐perforated borehole, were found to have the same periodicities as the sea tide, though some orders of magnitude larger than sea‐level or groundwater level fluctuations. Direct measurements in the aquifer through buried EC sensors demonstrate that EC measurements within the long‐perforated boreholes might be distorted due to vertical flow in the boreholes, whereas actual fluctuations of the transition zone within the aquifer are some orders of magnitude smaller. Considering these field data, we suggest that monitoring of the transition zone between fresh and saline water adjacent to the sea through long‐perforated boreholes is unreliable. EC fluctuations in short‐perforated boreholes (1 m perforation at the upper part of the transition zone) were somewhat larger than in the aquifer, but much smaller than those in the long‐perforated borehole. The short‐perforation diminishes the vertical flow and the distortion and therefore is more reliable for monitoring the transition zone in the shoreline vicinity. 相似文献
9.
Philip T. Harte 《Ground water》2013,51(6):822-827
Groundwater sampling from open boreholes in fractured‐rock aquifers is particularly challenging because of mixing and dilution of fluid within the borehole from multiple fractures. This note presents an alternative to traditional sampling in open boreholes with packer assemblies. The alternative system called ZONFLO (zonal flow) is based on hydraulic control of borehole flow conditions. Fluid from discrete fractures zones are hydraulically isolated allowing for the collection of representative samples. In rough‐faced open boreholes and formations with less competent rock, hydraulic containment may offer an attractive alternative to physical containment with packers. Preliminary test results indicate a discrete zone can be effectively hydraulically isolated from other zones within a borehole for the purpose of groundwater sampling using this new method. 相似文献
10.
Deep observation boreholes in the vicinity of active production wells in Honolulu, Hawaii, exhibit the anomalous condition that fluid-column electrical conductivity logs and apparent profiles of pore-water electrical conductivity derived from induction conductivity logs are nearly identical if a formation factor of 12.5 is assumed. This condition is documented in three boreholes where fluid-column logs clearly indicate the presence of strong borehole flow induced by withdrawal from partially penetrating water-supply wells. This result appears to contradict the basic principles of conductivity-log interpretation. Flow conditions in one of these boreholes was investigated in detail by obtaining flow profiles under two water production conditions using the electromagnetic flowmeter. The flow-log interpretation demonstrates that the fluid-column log resembles the induction log because the amount of inflow to the borehole increases systematically upward through the transition zone between deeper salt water and shallower fresh water. This condition allows the properties of the fluid column to approximate the properties of water entering the borehole as soon as the upflow stream encounters that producing zone. Because this condition occurs in all three boreholes investigated, the similarity of induction and fluid-column logs is probably not a coincidence, and may relate to aquifer response under the influence of pumping from production wells. 相似文献
11.
KV法在判定岩体完整性中的应用 总被引：4，自引：0，他引：4
使用某花岗岩体内16个钻孔的资料,用KV法分别对该岩体的强、中等、微风化层的完整性作出判断,并与钻孔揭示的实际情况进行比对,结果证明:在具备大量、较准确的波速测试数据的前提下,用KV法判断岩石的完整性所得出的结论和实际情况几乎完全一致。 相似文献
12.
Richard B. Greswell Véronique Durand Maria F. Aller Michael S. Riley John H. Tellam 《Ground water》2014,52(4):525-534
Forced gradient tracer tests between two boreholes can be used to study contaminant transport processes at the small field scale or investigate the transport properties of an aquifer. Full depth tests, in which tracer samples are collected just from the discharge of the abstraction borehole, often give rise to breakthrough curves with multiple peaks that are usually attributed to different flow paths through the aquifer that can rarely be identified from the test results alone. Tests in selected levels of the aquifer, such as those between packer‐isolated sections of the boreholes, are time consuming, expensive; and the identification of major transport pathways is not guaranteed. We present a method for simultaneously conducting multiple tracer tests covering the full depth of the boreholes, in which tracer sampling and monitoring is carried out by a novel multilevel sampling system allowing high frequency and cumulative sampling options. The method is applied to a tracer test using fluorescein conducted in the multilayered sandstone aquifer beneath the city of Birmingham, UK, producing six well‐defined tracer breakthrough curves. 相似文献
13.
随着对地下空间开发的日趋增加,地下空间的施工与利用安全问题越来越受到广泛关注,地下发育的岩溶对于地下空间的开发会造成诸多安全隐患,对人民的生产生活也会造成很多影响.跨孔地震CT技术已经广泛应用于岩石破碎带、溶洞等探测,为地下空间的开发利用及施工安全提供了重要的技术支撑.为了进一步研究该技术的成像精度,本文对影响跨孔地震... 相似文献
14.
Shulamit Gordon Martin Sharp Bryn Hubbard Ian Willis Chris Smart Luke Copland Jon Harbor Bradley Ketterling 《水文研究》2001,15(5):797-813
Studies of glacier hydrology rely increasingly on measurements made in boreholes as a basis for reconstructing the character and behaviour of subglacial drainage systems. In temperate glaciers, in which boreholes remain open to the atmosphere following drilling, the interpretation of such data may be complicated by supraglacial or englacial water flows to and from boreholes. We report on a suite of techniques used to identify borehole water sources and to reconstruct patterns of water circulation within boreholes at Haut Glacier d'Arolla, Switzerland. Results are used to define a number of borehole ‘drainage’ types. Examples of each drainage type are presented, along with the manner in which they influence interpretations of borehole water‐levels, borehole water‐quality data, and borehole dye traces. The analysis indicates that a full understanding of possible borehole drainage modes is required for the correct interpretation of many borehole observations, and that those observations provide an accurate indication of subglacial conditions only under relatively restricted circumstances. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
15.
Vertical geophone arrays in boreholes have been used for many years to study seismic velocities by investigating the first arrivals of records. The development of the vertical seismic profiling (VSP) technique shows possibilities of using the reflected events to close the gap between interpretation of conventional seismic data and physical observations made in the well. Reflected events recorded by vertical arrays (as in VSP) generally have higher signal-to-noise ratio, larger bandwidth and can easily be separated from multiples. The new Continuous Vertical Array (CVA) technique combines vertical arrays in several boreholes with a line of source points near the surface. The result is a multi-covered seismic line similar to that of a conventional seismic survey, but it retains the benefits of observations with vertical arrays. The possibilities of the new technique are discussed with the aid of theoretical considerations, model studies, and a first field case using nine boreholes 500 m apart with depths of 400 m. New data acquisition and processing techniques (mainly migration before stack) have been developed. The CVA-seismic method is still in the development stage but promises new possibilities for detailed surveys in difficult areas. 相似文献
16.
On the retrieval of moment tensors from borehole data 总被引：5，自引：0，他引：5
Václav Vavry&#;uk 《Geophysical Prospecting》2007,55(3):381-391
The complete moment tensors of seismic sources in homogeneous or vertically inhomogeneous isotropic structures cannot be retrieved using receivers deployed in one vertical borehole. The complete moment tensors can be retrieved from amplitudes of P‐waves, provided that receivers are deployed in at least three boreholes. Using amplitudes of P‐ and S‐waves, two boreholes are, in principle, sufficient. Similar rules also apply to transversely isotropic media with a vertical axis of symmetry. In the case of limited observations, the inversion can be stabilized by imposing the zero‐trace constraint on the moment tensors. However, this constraint is valid only if applied to observations of shear faulting on planar faults in isotropic media, which produces double‐couple mechanisms. For shear faulting on non‐planar faults, for tensile faulting, and for shear faulting in anisotropic media, the zero‐trace constraint is no longer valid and can distort the retrieved moment tensor and bias the fault‐plane solution. Numerical modelling simulating the inversion of the double‐couple mechanism from real data reveals that the errors in the double‐couple and non‐double‐couple percentages of the moment tensors rapidly decrease with increase in the number of boreholes used. For noisy P‐ and S‐wave amplitudes with noise of 15% of the top amplitude at each channel and for a velocity model biased by 10%, the errors in the double‐couple percentage attain 25, 13 and 6% when inverting for the double‐couple mechanism from one, two and three boreholes. 相似文献
17.
Gradient and Mise-à-la-Masse IP/Resistivity surveys were conducted on a group of 19 boreholes in Eagle’s Nest, Eagle One magmatic sulfide deposit in northern Ontario, Canada. The surveys were conducted as a follow-up to the many drilled boreholes, some of which missed the target. The surveys were intended to map the distribution of the ore mineralization, outline the deposit hosted by mafic and ultramafic rocks and then guide the drilling of new boreholes. Joint Gradient and Mise-à-la-Masse data inversion produced 3D chargeability and conductivity models. The inverted 3D models in turn help delineate the outline of the mineralized zone, and determine the shape, size, strength and economic viability of the deposit. The Gradient array determined the direction of the mineralization with respect to the boreholes, and the Mise-à-la-Masse array examined the highly conductive subsurface bodies and their surroundings. The mapped ore zone shows close similarity to the 0.5 Cu% and 1.05 Ni% iso-surfaces that are produced from core assay result confirming the reliability of the results obtained in this study. 相似文献
18.
《Journal of Geodynamics》2010,49(3-5):115-119
Tides and barometric pressure variations cause pore pressure changes in the solid earth. In boreholes which are hydraulically connected to confined aquifers these pore pressure changes can be observed as water level variations. In case of confined aquifers boreholes can be regarded as volumetric strainmeters. From June 2004 until May 2005 a large scale injection experiment was realised in the pilot borehole (4000 m) at the German Continental Deep Drilling (KTB) site in Bavaria. During this test the injection induced deformation was observed by a tiltmeter array around KTB consisting of five tiltmeter stations at horizontal distances from 1.6 to 3 km from the injection borehole. At each station the local groundwater level was observed in depths between 30 and 50 m. The pore pressure was recorded in the boreholes. The time series were checked for tidal signals and injection influence. The injection was not verified presumably due to the fact that the penetration of the injected water was controlled by local geology and tectonic faults zones. Although the boreholes extending only to shallow depth tidal signals are clearly observable in at least two of five stations. On December the 26th 2004 the Sumatra–Andaman earthquake occurred which is clearly detectable in the pore pressure variations at all five stations. 相似文献
19.
应用断层气氡进行地震监测预报 总被引：4，自引：2，他引：2
概述了断层气氡观测点的地理位置,地质环境和观测条件,用最优周期谱持和多元逐步回归分析方法对观测资料进行了详细分析,分析结果表明观测曲线具有“冬高夏低”的年动态变化和固体潮变化特征。其中固体潮变化是断层气氡进行地震监测预报的力不基础。 相似文献
20.
鄂西渝东地区是中国南方海相油气勘探的重要区块,又是目前页岩气勘探的热门地区,该地区晚燕山-喜马拉雅期以来长期遭受隆升剥蚀.剥蚀量是烃源岩热演化、油气藏形成与演化、资源量计算和盆地模拟中不可缺少的基础参数.考虑到剥蚀量恢复方法固有的局限性和适用条件,本文在分析了古温标镜质体反射率Ro剖面特征之后,采用古地温梯度反演法进行钻井剥蚀量恢复,然后分析钻井剥蚀量与钻井开孔层位之间的相关性,再与地质图相结合编制剥蚀量平面分布图.结果表明：鄂西渝东地区古温标Ro剖面不存在明显的“错断”、“跳跃”现象,记录的古地温为达到最大埋深时的古地温;钻井剥蚀量与钻井开孔层位之间具有明显的相关性,开孔层位越老,剥蚀量越大,反之亦然;晚燕山-喜马拉雅期剥蚀量总体上从东往西逐渐变小.东部的利川复向斜剥蚀量为2000~4000 m,中部的石柱复向斜为1500~2500 m,方斗山以西为1000~1500 m. 相似文献