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1.
A series of 2D apparent resistivity data were generated over two synthetic models representing different geological or environmental
conditions commonly associated with geophysical applications for hydrogeological, environmental and engineering investigations.
The apparent resistivity data were generated for the following arrays: Wenner-alpha (WA), Wenner-beta (WB), Wenner–Schlumberger
(WSC), dipole–dipole (DDP), pole–dipole (PDP) and pole–pole (PP) arrays, which were paired such that apparent resistivity
data for 2D profiles in a parallel direction are obtained with a particular array type and those in a perpendicular direction
are observed with a different array type. The 2D apparent resistivity data for the orthogonal paired-arrays were then collated
to 3D data sets. The effectiveness and efficiency of the orthogonal paired-arrays in 3D geoelectrical resistivity imaging
were evaluated by determining the mean absolute anomaly effects of the electrode configurations on the synthetic models. The
results show that DDP–PDP, DDP–PP, DDP–WSC, PDP–PP, DDP–WB, PDP–WB and WB–WSC orthogonal paired-arrays produced higher anomaly
effects on the synthetic models. This indicates that DDP–PDP, DDP–PP, DDP–WSC, PDP–PP, DDP–WB, PDP–WB and WB–WSC orthogonal
paired-arrays are more sensitive to 3D features of the geologic models than the other orthogonal paired-arrays investigated. 相似文献
2.
3.
Surface geophysical investigations of landslide at the Wiri area in southeastern Korea 总被引:1,自引:1,他引:0
A geophysical survey was undertaken at Wiri area of the Andong in southeastern Korea to delineate subsurface structure and
to detect the fault zone, which affected the 1997 mountain–hill subsidence and subsequent road heaving initiated by the intense
rainfall. Electrical resistivity methods of dipole–dipole array profiling and Schlumberger array sounding and seismic methods
of refraction and reflection profiling were used to map a clay zone, which was regarded as the major factor for the landslide.
The clay zone was identified in electrical resistivity and seismic sections as having low electrical resistivity (<100 Ωm)
and low seismic velocity (<400 m/s), respectively. The clay zone detected by using geophysical methods is well correlated
with its distribution from the trench and drill-core data. The results of the electrical and seismic surveys showed that slope
subsidence was associated with the sliding of saturated clay along a fault plane trending NNW–SSE and dipping 10°–20° SW.
However, the road heaving was caused by the slope movement of the saturated clay along a sub-vertical NNE-trending fault. 相似文献
4.
The city of Burdur, which is built on an alluvium aquifer, is located in one of the most seismically active zones in southwestern
Turkey. The soil properties in the study site are characterized by unconsolidated and water-saturated sediments including
silty, clayey and sandy units, and shallow groundwater level is the other characteristic of the site. Thus, the city is under
soil liquefaction risk during a large earthquake. A resistivity survey including 189 vertical electrical sounding (VES) measurements
was carried out in 2000 as part of a multi-disciplinary project aiming to investigate settlement properties in Burdur city
and its vicinity. In the present study, the VES data acquired by using a Schlumberger array were re-processed with 1D and
2D inversion techniques to determine liquefaction potential in the study site. The results of some 1D interpretations were
compared to the data from several wells drilled during the project. Also, the groundwater level map that was previously obtained
by hydrological studies was extended toward north by using the resistivity data. 2D least-squares inversions were performed
along nine VES profiles. This provided very useful information on vertical and horizontal extends of geologic units and water
content in the subsurface. The study area is characterized by low resistivity distribution (<150 Ωm) originating from high
fluid content in the subsurface. Lower resistivity (3–30 Ωm) is associated with the Quaternary and the Tertiary lacustrine
sediments while relatively high resistivity (40–150 Ωm) is related to the Quaternary alluvial cone deposits. This study has
also shown that the resistivity measurements are useful in the estimation of liquefaction risk in a site by providing information
on the groundwater level and the fluid content in the subsurface. Based on this, we obtained a liquefaction hazard map for
the study area. The liquefaction potential was classified by considering the resistivity distributions from 2D inversion of
the VES profiles, the types of the sediments and the extended groundwater level map. According to this map, the study area
was characterized by high liquefaction hazard risk. 相似文献
5.
Many achievements have been made in experimental studies of hydrocarbon migration in the clastic reservoir. On the other hand,
few migration experiments have been reported in the carbonate reservoir simulation realm. This article is a tentative experimental
study on hydrocarbon migration and accumulation in the carbonate reservoir, which is a complex media that includes a pore
system and fracture system. This microcosmic experiment simulates oil-water displacement using a real core model. Plentiful
seepage phenomena were observed in the microcosmic experiments. Three kinds of pathways were found in the plane: parallel
pathway, oblique-cross pathway and network pathway. Three types of flow were found: continuous flow, sectioning flow and their
combination. Three driving fronts were found in the experiment: piston front, encircle front and impulse front. All these
vary with many factors such as fluid pressure, oil saturation, fissure configuration and wettability, and these factors affect
each other. The results show that the relation between the fluid pressure and volume of flow is a complex segmenting correlation,
instead of a simple positive correlation like the pipe flow that follows Darcy’s law. The relation between fluid pressure
and the speed of flow also follows the same correlation. Speed of flow relates to the angle and width of the fissure. Speed
of flow in the wide fissure that has an acute angle with the pressure gradient is faster than that in a narrow fissure with
a high angle with the pressure gradient.
Translated from Geological Review, 2006, 52(4): 570–576 [译自: 地质 论评] 相似文献
6.
Recently in China, soil–cement is widely used to improve the soft ground in the highway construction engineering. Literature
studies are mainly investigating the mechanical properties of the soil–cement, while its properties of the electrical resistivity
are not well addressed. In this paper, the properties of the electrical resistivity of the reconstituted soil-cement and the
in situ soil–cement columns are investigated. The test results show that the electrical resistivity of the soil–cement increases
with the increase in the cement-mixing ratio and curing time, whereas it decreases with the increase in the water content,
degree of saturation and water–cement ratio. A simple equation is proposed to predict the electrical resistivity of soil–cement
under the condition of the specified curing time and water–cement ratio. It is found that the electrical resistivity has a
good relationship with the unconfined compression strength and blow count of SPT. It is expected that the electrical resistivity
method can be widely used for checking/controlling the quality of soil–cement in practice. 相似文献
7.
S xxxV Suryanarayana Rao S Murali V L S Bhimasankaram 《Journal of Earth System Science》1981,90(1):75-83
A new variant of the four-electrode system is proposed for geophysical resistivity investigations, particularly for profiling over conductive bodies. Model tank resistivity profiling experiments with Wenner, Schlumberger and the proposed T-shaped four-electrode arrays were carried out over a thin conducting vein type model to evaluate the efficacy of the new array. The proposed array appears to possess a larger response, a greater depth of investigation and a higher vertical resolution in detecting conducting bodies, as compared to the two-conventional arrays. 相似文献
8.
John H. Paul Molly R. McLaughlin Dale W. Griffin Erin K. Lipp Rodger Stokes Joan B. Rose 《Estuaries and Coasts》2000,23(5):662-668
Viral tracer studies have been used previously to study the potential for wastewater contamination of surface marine waters in the Upper and Middle Florida Keys. Two bacteriophages, the marine bacteriophage ϕHSIC and theSalmonella phage PRD1, were used as tracers in injection well and septic tank studies in Saddlebunch Keys of the Lower Florida Keys and in septic tank studies in Boot Key Harbor, Marathon, of the Middle Keys. In Boot Key Harbor, both phages were detected in a canal adjacent to the seeded septic tank within 3 h 15 min of the end of the seed period. The tracer was then detected at all sampling sites in Boot Key Harbor, including one on the opposite side of U.S. Highway 1 in Florida Bay, and at an Atlantic Ocean beach outside Boot Key Harbor. Rates of migration based on first appearance of the phage ranged from 1.7 to 57.5 m h−1. In Saddlebunch Keys, ϕHSIC and PRD1 were used to seed a residential septic tank and a commercial injection well. The septic tank tracer was not found in any surface water samples. The injection well tracer was first detected at a site most distant from the seed site, a channel that connected Sugarloaf Sound with the Atlantic Ocean. The, rate of tracer migration from the injection well to this channel ranged from 66.8 to 141 m h−1. Both tracer studies showed a rapid movement of wastewater from on-site sewage treatment and disposal systems in a southeasterly direction toward the reef tract and Atlantic Ocean, with preferential movement through tidal channels. These studies indicate that wastewater disposal systems currently in widespread use in the Florida Keys can rapidly contaminate the marine environment. 相似文献
9.
Two-dimensional electrical resistivity tomography data acquired on the crest of the embankment are distorted by the 3D effect of the embankment geometry, reservoir water level and abutment. The distortion affects seriously the final solution of the 2D inverse problem. By comparing the apparent resistivity pseudosections from a 3D and 2D electrical resistivity model of the embankment, the distortion degrees of the apparent resistivity pseudosections along the axis on the crest were estimated for the cases of reservoir and which does not contain water. The obtained results indicate that the distortion degree acquired in the case of a reservoir that contains water was much less than that in the case of the reservoir that does not contain water. In the case of reservoir that contains water, the apparent resistivity pseudosections of the P–P and ED–ED arrays had the largest distortion degree and of D–D, W–S and P–D arrays had the smallest distortion degree. In the case of the reservoir that does not contain water, the apparent resistivity pseudosection of P–P array had the smallest distortion among all arrays. Through modeling investigation, a correction process to reduce the distortion of the apparent resistivity pseudosection was proposed. The correction process was tested in the embankment model, and two field works were carried out in the To Lich River in Hanoi and Khuan Cat embankment in Lang Son province, Vietnam. It is possible to bring the distortion of the apparent resistivity pseudosection down to 2.8–13.9%, depending on the type of electrode arrays and the type of reservoirs, containing or does not contain water. The distortion correction of the apparent resistivity pseudosection is strongly recommended before doing the 2D inverse interpretation. 相似文献
10.
Application of quantitative grain fluorescence techniques to study subtle oil migration pathway of lithological reservoir 总被引:1,自引:0,他引:1
This paper analyzes the quantitative grain fluorescence (QGF) and quantitative grain fluorescence on extract (QGF-E) properties
of 101 rock samples by using quantitative grain fluorescence techniques. The samples are collected from five wells in tight
sandstone and thin siltstone in the third sector of the Shahejie Formation in the Niuzhuang sag of the Dongying depression.
It was observed that both the tight sandstone and thin siltstone show relatively high fluorescence intensity of hydrocarbon,
which suggests that they are possibly good subtle oil-migration pathways in the present or geological time. These thin subtle
oil-migration pathways afford important clues for the researches on hydrocarbon accumulation in lithological reservoirs in
the middle and lower of Es
3 in deep sag zone, which has the hydrocarbon source from the upper of Es
4 when there is no apparent fault playing oil migration conduits to connect lithologic traps and deep source rocks. This study
shows good prospect of QGF techniques in discriminating oil migration pathways and paleo-oil zones. The results of this study
may be of great significance to the researches on hydrocarbon accumulation mechanism of subtle reservoirs in the Dongying
depression and other areas.
__________
Translated from Acta Geologica Sinica, 2007, 81(2): 250–254 [译自: 地质学报] 相似文献
11.
Delineation of saltwater intrusion into the freshwater aquifer of Lekki Peninsula,Lagos, Nigeria 总被引:2,自引:0,他引:2
A. A. Adepelumi B. D. Ako T. R. Ajayi O. Afolabi E. J. Omotoso 《Environmental Geology》2009,56(5):927-933
Recently, the deterioration of water quality in the coastal zones of Lekki Peninsula area of Lagos due to saltwater infiltration
into the freshwater aquifer has become a major concern. With the aim of providing valuable information on the hydrogeologic
system of the aquifers, the subsurface lithology and delineating the groundwater salinity, vertical electrical resistivity
(VES) sounding survey was carried out utilizing surface Schlumberger electrode arrays, and electrode spacing varying between
1 and 150 m. The DC resistivity surveys revealed significant variations in subsurface resistivity. Also, the VES resistivity
curves showed a dominant trend of decreasing resistivity with depth (thus increasing salinity). In general, the presence of
four distinct resistivity zones were delineated viz.: the unconsolidated dry sand (A) having resistivity values ranging between
125 and 1,028 Ωm represent the first layer; the fresh water-saturated soil (zone B) having resistivity values which correspond
to 32–256 Ωm is the second layer; the third layer (zone C) is interpreted as the mixing (transition) zone of fresh with brackish
groundwater. The resistivity of this layer ranges from 4 to 32 Ωm; while layer four (zone D) is characterized with resistivities
values generally below 4 Ωm reflecting an aquifer possibly containing brine. The rock matrix, salinity and water saturation
are the major factors controlling the resistivity of the formation. Moreover, this investigation shows that saline water intrusion
into the aquifers can be accurately mapped using surface DC resistivity method. 相似文献
12.
A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry
of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company.
One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth
of 1000–1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential
threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence
due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and
the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference
of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several
scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land
subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer
drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing
a rebound of 0.6–0.7 cm.
Electronic Publication 相似文献
13.
Geophysical surveys were carried out in an arsenic contaminated area, in the Ron Phibun District in southern Thailand. Here, tin and associated minerals, i.e. arsenopyrite and pyrite, have been extracted from granites and natural processes and the mining activities led to arsenic contamination in the environment. Electrical resistivity and self-potential (SP) were used to define the distribution of arsenic contamination in the groundwater. Resistivities of 25–100 Ωm and a positive SP anomaly of 66.0 mV were observed in an area where the arsenic content in auger water at 3.5–5.0 m depths was high, 0.5–5.0 mg/l. Integrated interpretation of resistivity, seismic refraction, GPR and gravity data gave a clear image of subsurface shallow structures (< 30 m depths). There was a good correlation between the resistivity and the gravity data. A subsurface rise was found, which possibly acts as a naturally buried dam, separating a high-contaminated area from a low contaminated area. 相似文献
14.
Measurements of the concentration and size distribution of aerosol particles in the size-ranges of 0.5–20 μm and 16–700 nm
diameters were made during six fog episodes over the south Indian Ocean. Observations show that concentrations of particles
of all sizes start decreasing 1–2 hours before the occurrence of fog. This decrease is more prominent for coarse particles
of >1 μm diameter and continues until 10–20 minutes before the onset of fog when particle concentrations in all size ranges
rapidly increase by one/two orders of magnitude in ∼20 minutes. Thereafter, concentrations of particles of all sizes gradually
decrease until the dissipation of fog. After the fog dissipation, concentrations of coarse mode particles rapidly increase
and restore to their pre-fog levels but concentrations of the Aitken mode particles decrease slowly and reach their pre-fog
levels only after 1–2 hours. The net effect of fog is to change the bimodal size distributions of aerosols with a coarse mode
at 1.0 μm and an accumulation mode at 40–60 nm to a power law size distribution. It is proposed that the preferential growth
and sedimentation of the coarse mode hygroscopic particles in the initial phase cause a large decrease in the aerosol surface
area. As a result, the low vapour pressure gases which were initially being used for the growth of coarse mode particles,
now accelerate the growth rates of the accumulation and Aitken mode particles. 相似文献
15.
Subash Chandra V. A. Rao N. S. Krishnamurthy S. Dutta Shakeel Ahmed 《Hydrogeology Journal》2006,14(5):767-776
An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.An erratum to this article can be found at 相似文献
16.
Subash Chandra V. A. Rao N. S. Krishnamurthy S. Dutta Shakeel Ahmed 《Hydrogeology Journal》2006,14(6):1042-1051
An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.The online version of the original article can be found at 相似文献
17.
Robert G. Garrett 《Mathematical Geology》1978,10(5):481-494
An abundance model resource appraisal has been undertaken for 10 mineral commodities in Canada: nickel, copper, zinc, lead,
molybdenum, uranium, silver, gold, chromium, and tin. The purpose of the appraisal was to investigate the applicability of
the model to the Canadian situation. Resource appraisals for the first 6 of the commodities studied have been published following
deposit modeling studies. For many other commodities studied have been published following deposit modeling appraisals. The
demonstration of the relevance of the abundance model to Canada would allow its application in such cases. The data presented
in this paper indicate that the approximate relation, resource (short tons)=abundance (%)×1010. holds true for all commodities studied except chromium and tin. As the resources versus abundances relationship observed
on a global scale is observable in Canada, it is concluded that Canada is a sufficiently large fraction (∼7%) of the earth's
continental crust to represent a valid sample of that crust. Canada appears to be relatively well endowed with resources of
copper, molybdenum, lead, and zinc, and poorly endowed with chromium and tin. It is proposed that the intersection of national
boundaries with the boundaries of the world's metallogenic provinces is of greater importance than the intensity of past search,
a feature that has been suggested in other studies. If these areas overlap, a nation may be self sufficient in a commodity:
if they do not, the nation must import, or find a nationally available substitute. The sources of information used in the
appraisal are outlined together with an analysis of the problems encounterea and the time requirements.
This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications
in Resource Studies” held at Taita Hills Kenya, November 8–15, 1977. 相似文献
18.
The occurrence, movement and control of groundwater, particularly in hard-rock areas, are governed by different factors such
as topography, lithology, structures like fractures, faults and nature of weathering. An attempt is made in the present study
to investigate the extent of the influence of structures such as fractures and thereby delineate the nature of subsurface
lithology with the help of an electrical resistivity method. For this study, the Upper Gunjanaeru River basin, Cuddapah district
Andhra Pradesh was chosen to determine groundwater potentials. In order to understand the significance of the fracture pattern,
geological, hydrogeomorphological and lineament maps were prepared based on the field data and also from the LANDSAT TM imagery.
Further, electrical resistivity surveys were conducted to determine the subsurface lithology and also to confirm the studies
of LANDSAT imagery. The isoresistivity contour map has been prepared based on the 45 VES conducted to determine the resistivity
variations in the study area. The isoresistivity contours obtained were found to conform to the structural trends obtained
by geological studies and also confirm the relationship between the structure and secondary porosity present in the rocks.
The lineaments in the area have two preferred directions. One set is a NE-SW direction (N 30°–70° E; S 30°–70° W) and another
is a NW-SE direction (N 0°–30° W; S 0°–30° E and N 60°–80° W; S 60°–80° E). The water-table contour map shows that the direction
of groundwater flow is south to north.
Received: 3 March 1997 · Accepted: 17 June 1997 相似文献
19.
Wakgari Furi Moumtaz Razack Tigistu Haile Tamiru A. Abiye Dagnachew Legesse 《Environmental Earth Sciences》2011,62(6):1323-1335
Rise of groundwater level becomes an emerging concern at Wonji irrigation field, Main Ethiopian Rift. An integrated study
based on geophysical resistivity methods is conducted at Wonji wetland to understand the link between irrigation water and
the shallow aquifer system as well as to confirm the current concern of groundwater rise. The study was also intended to improve
the uncertainty of understanding the hydrogeology of Wonji wetland including the extent and direction of groundwater–surface
water interaction. The vertical and horizontal contacts between the different geological series of the Wonji area are resolved
with 2D high-resolution geophysical imaging. Results from both VES and 2D tomography show low resistivity layers under Wonji
irrigation field with narrow ranges in resistivity variation which corresponds to a homogeneous saturated layer. The geoelectric
sections reveal two fault systems running NW–SE and N–S directions which impede lateral groundwater flow. Furthermore, groundwater
is converged towards the Wonji irrigation site strained by these fault systems. The geophysical results show strong link between
irrigation water and the shallow unconfined aquifer as well as among the local and regional flow systems. 相似文献
20.
为了评估观测质量,本文结合大柏舍地震台电测深资料,采用水平层状介质模型分析了该台站对称四极装置深井地电阻率观测时影响系数随电极深度和观测极距的变化。分析结果表明:大柏舍台现有的深井地电阻率观测水平测道虽然能有效地抑制来自地表的干扰,但是由于观测极距较小,不能很好地反映深部介质电阻率的变化信息;垂直测道因电极埋深位于地下水位变动层位,观测数据受地下水位波动影响较大,较难识别来自深部介质的信息。为有效地记录可能的孕震信息,水平测道极距AB/2取250~350 m、埋深H>150 m能满足需求,并建议增加NS向水平测道观测。 相似文献