- Home
- Conferences
- Conference Proceedings
- Conferences
7th International Congress of the Brazilian Geophysical Society
- Conference date: 28 Oct 2001 - 31 Oct 2001
- Location: Salvador, Bahia, Brazil
- Published: 28 October 2001
81 - 100 of 465 results
-
-
Imageamento Com Gpr De Fraturas Em Aqüíferos Fissurais: O Caso De Equador/Rn
O trabalho aqui apresentado visa indicar o
GPR (Ground Penetrating Radar) como método de
prospecção de feições geológicas em alguns terrenos
cristalinos capeados por coberturas sedimentares. Em
diversas porções da região NE do Brasil, a exemplo
de Equador-RN, as características geológicas e
climáticas favorecem o uso do GPR. Estas
características se refletem basicamente sob a forma de
um capeamento sedimentar pouco espesso e
relativamente resistivo, o qual não interfere
efetivamente na propagação das ondas
eletromagnéticas geradas pelo equipamento.
Com base no truncamento de refletores
subhorizontais referentes ao bandamento local, pôdese
identificar diversos sistemas de fraturas. Estes
fraturamentos diferem entre si basicamente com
respeito ao mergulho (desde baixo ângulo a
subverticalizado) e ao tipo de conectividade.
A consistência dos resultados com GPR é
atestada pelos dados dos levantamentos de
eletroresistividade e VLF elaborados no mesmo local.
-
-
-
Levantamento Experimental Gpr No Rio Taquari, Bacia Do Pantanal Matogrossense
An experimental investigation has been carried out
using GPR - Ground Penetrating Radar methods in
Taquari River, located in Pantanal Matogrossense
Basin - Brazil, in order to understand the silting
process on the river and also to map the channels
along the river, that is essential to local navigation.
Many GPR profiles have been carried out in Lower
Taquari river, near Santa Maria and Porto Santa Luzia
farms. Preliminary interpretations were encouraging,
allowing to locate the channels of the river and the
occurrence of very big sand deposits, showing the
viability of GPR application to Taquari river
sedimentation process studies. All data collected are
now been analysing in order to understand the local
dynamic sedimentation process, as part of a MSc.
Dissertation in progress by an IAG-USP student.
Results from these geophysical investigations are
going to serve as guidance to multidisciplinary
studies of Pantanal Program, by government of Mato
Grosso do Sul State.
-
-
-
Levantamento Geofísico Utilizando O Método Gpr Na Mineração Millennium (Pb)
This paper show the results of a GPR survey carried
out in a excellent geological environment, allowed
penetration exceeding 60 meters with 25 MHz antenna.
Several boreholes in the survey line show that the
GPR data agree closely with the depth of Fm.
Barreiras sediments covered by sand dunes.
-
-
-
Levantamento Gpr Em Afloramentos Turbidíticos Da Bacia De Almada-Ba
Authors Marco Ceia, Abel Carrasquilla and Jandyr TravassosIn onshore Almada Basin, northeast of Brazil, sandy
and/or conglomeratic turbidites and shales outcrops of
Urucutuca Formation occurs. These rocks are part of
an exhumed portion of the filling-section of the
Almada Canyon. Such outcrops are unique examples
of passive margin transgressive marine sequence
turbidites in Brazil, which were sedimented during
the Maastritchian/Campanian. They are analogues to
some important turbidite reservoirs of Campos Basin,
which is the most productive oil basin in Brazil. To
aid studies of internal geometry and facies association
which will help to improve the knowledge of the
properties of such kind of rocks, a GPR (Ground
Penetrating Radar) survey was performed in this
region. This work aims to show the first results
obtained at one of the outcrops.
-
-
-
Localização De Fraturas Em Rochas Graníticas, No Município De Capão Bonito-Sp, Brasil
Authors Abad Oliveira Souza Júnior and Jorge Luís PorsaniGround Penetrating Radar - GPR and Resistivity
methods were used with the objective to detect
fracture zones and the top of fresh rock, in
ornamental granite mine, located near Capão
Bonito City, São Paulo State, Brazil. Eight profiles
of reflections GPR and 19 WARR’s Soundings
were acquired using antennas of 25, 50, 100 and
200 MHz. Two vertical electrical sounding were
acquired too. Analysis of GPR’s profiles allowed to
locate stronger dipping and sub horizontal
reflectors, probably related with the fractures zones
filled with water. Besides, were identified two
shadow zones that can be related with intrusions of
diabase’s dike, and one hyperbolic reflector with a
boulder. The fresh rock was identified about 23m of
depth. The results obtained probably will go help
the project of mine engineering looking forward to
advancing of work front.
-
-
-
Mapeamento De Pluma Contaminante De Hidrocarbonetos A Partir De Seções Gpr Em Um Posto De Abastecimento Em Fortaleza - Ceará
The Ground Penetrating Radar (GPR) technique
can be helpful in mapping sites of shallow hydrocarbon
contamination (LNAPL). The radar signals are
severely attenuated above LNAPL contaminated zones,
allowing its detection and monitoring. During the
remediation procedure of a contaminated gas station
in Fortaleza, Ceará State, GPR surveys were carried
out to delineate the LNAPL plume in the subsurface.
The dispersion characteristics of this hydrocarbon
contamination could be identified throughout the
unsaturated zone above the water table.
-
-
-
Resultados Da Utilização De Gpr Na Localização De Cavidades (Pockets) No Pegmatito De Morro Redondo, Coronel Murta, Mg
More LessThe GPR method was used to identify pockets
inside an underground mine, which was mined before
by artisan miners, at Morro Redondo, pegmatite
deposit in Minas Gerais State (Brazil). This work
points out the difficulties to interpret the GPR data
due to the presence of tunnels and the irregularities of
walls, and by the use of unshield antennas. The
method was able to show the contacts between the
pegmatite vein and surrounding rocks (schist), and
also had a marginal results, which was the
localization of previously unknown tunnels and
galleries placed in the lower parts of the pegmatite body.
-
-
-
Uso Do Gpr Na Caracterização Interna De Feições Geológicas Cenozóicas No Litoral Centrooeste Do Ceará, Brasil
Ground Penetrating Radar (GPR) profiles have
been recorded in the coastal region of Lagoinha, in Ceará
State, NE Brazil, to investigate internal structures and
facies of the partially buried sedimentary units. GPR
profiles show reflection patterns which can be assigned
to the lithified sandstones of Barreiras Formation
(Tertiary) and beach rocks (Quaternary). Furthermore,
vibra-cores were collected to correlate GPR reflections
with changes in subsurface lithologies.
-
-
-
Utilização De Gpr E Eletrorresistividade Para Mapeamento De Dutos Decorrentes De Piping, Gouveia, Mg
A piping system was recognized using different
geophysical methodologies to access the subsurficial
distribution of its channels. The responses of three
antennas (100, 200, and 400 MHz) of the groundpenetrating
radar (GPR) method were compared, as
well as resistivity profiles obtained with different
electrode arrays (Cacau, Wenner, and dipole-dipole).
The best GPR results were obtained with the 100
MHz antennas, which was used to achieve five
profiles to demarcate the path of the pipe. The pipe
was well identified by using the Cacau (with fixed
electrodes with offset of 40 meters) and Wenner
arrays, and all the other profiles has indicated a
second pipe unrelated to the main pipe.
-
-
-
Utilização Do Gpr Na Investigação Da Estratigrafia Da Região Costeira De Itaipuaçú – Maricá (Rj)
O principal objetivo deste estudo é o de investigar
a estratigrafia Quaternária costeira, num trecho da
região da praia de Itaipuaçú, município de Maricá,
Estado do Rio de Janeiro, utilizando como
ferramenta básica o GPR (Radar de Penetração no
Solo). A praia de Itaipuaçú possui um arco praial
de aproximadamente 10 Km de extensão, e é
caracterizada por um perfil refletivo, com ondas
de alta energia e principalmente pela característica
textural das areias (muito grossas, arredondadas)
formadas por quartzo puro transparente, o que
destoa do padrão das outras praias que formam o
litoral leste do Estado do Rio de Janeiro.
-
-
-
Abordagem Geofísica Em Terrenos Sedimentares Costeiros Baseada Em Técnicas De Eletrorresistividade, Eletromagnético Indutivo E Inversões E Sua Aplicação À Prospecção De Água Subterrânea (Região De Cascavel – Estado Do Ceará)
More LessResistivity methods (lateral profile and vertical soundings) were integrated with eletromagnetic data derived from EM-34. Also, the combined data inversion (ER+EM) were carry out showing the potentiality of the integrated geophysical techniques to the study of groundwater in coastal regions of the State of Ceará, NE Brazil. A joint interpretation of the above techniques, show that the crystalline structure under the sedimentary cover were the most important zone to the water contribution in several wells in Cascavel region. Several anomalies related to low conductivity zones represent good places for groundwater prospecting.
-
-
-
Caracterização Isotópica Do Aqüífero São Sebastião Na Região Do Pólo Petroquímico De Camaçari – Ba
The groundwater reservoirs from the São Sebastião
Formation in the region of Camaçari – Dias D´Ávila
are intensively exploited through deep well pumping
for industrial and urban uses. The geometry of the
reservoirs is defined by sandstones blocks
interlayered by shale-siltstone sequences in a geologic
context separated by faults. The exit temperature of
the water of the production wells allowed to identify
the capture zone of water that varied from the
superficial part of the aquifer to more than 300 m of
depth. The isotopíc composition of the groundwater
was found very homogeneous and close to the
average composition of precipitation in the nearby
region of Salvador, indicating a local recharge of
these aquifers without participation of transported
water from long distance by a regional flow system in
the deep layers. The difference between the isotopic
composition of surface water (rivers and dams) and
monitoring wells with the groundwater indicated no
direct connection between these water bodies.
-
-
-
Comparação Do Desempenho Dos Métodos Eletroresistivo E Transiente Eletromagnético Num Caso Especifico De Prospecção De Águas Subterrâneas
Authors Alfredo Moisés Vallejos Carrasco and Luis RijoThe resistivity method is the most used geophysical
prospecting technique for groundwater exploration.
However, it is not easy to use it in inhabited areas due
to the necessity to spread electrical wires for more
than one kilometer, depending on the desired
investigation depth. The time domain electromagnetic
(TEM) method, also used for groundwater
exploration, does not have this disadvantage, because
this inductive method uses a square loop whose
dimension is not an obstacle to be used in inhabited
places. On the other hand, TEM is more sensible to
cultural electrical noises.
To compare the performance of these techniques in an
urban area, we simulated and interpreted vertical
electric and TEM soundings through programs
developed by Rijo (1994ab,1996). In this comparison
we considered the 21 vertical electric soundings
models using an arrangement type Schlumberger and
synthetic curves for TEM.
As a result, from the apparent resistivity values
obtained of these methods, we derive a linear
relationship, in bilogaritmic scale, between the
spacing (meters) and the time (miliseconds). Thus, it
is possible to estimate a desired investigation depth in
urban areas using the TEM when the application of
the resistivity method is limitated by the accessibility.
-
-
-
Contribuição Da Sondagem Elétrica Vertical À Hidrogeologia Da Bacia Do Paraná No Município De Juscimeira-Mt
More LessThis study was done in four areas of Juscimeira’s
municipal (MT) Brazil and it was used the
Vertical Electrical Sounding method to determine
the vertical dimensions of the geologic units that
form the Parana’s Basin. The study allowed to
know the depth of the top and the thickness of
Furnas/Ponta Grossa Formations and
Furnas/Ponta Grossa Transition. Theses
information will guide the drilling of deep wells
whose objective is the exploitation of Furnas’
aquifer. The knowledge of the thickness of
Furnas’ aquifer is an important prerequisite to the
determination of the reserves of water at this
aquifer, while the thickness of the others units
have a relevant role at the studies of the
vulnerability to the contamination of Furnas’ aquifer.
-
-
-
Correlation Of Electrical And Hydraulic Conductivities Of Porous Aquifer – A Critique
Authors Sri Niwas and O.A.L. de LimaThis paper recollects the most important existing
equations derived for electrical and hydraulic effects
by considering simple aquifer models – non-shaly
and shaly sands. A critique about the possible
correlation between electrical and hydraulic
conductivity is presented, vis-à-vis estimation of the
later from the former with a requisite confidence.
Only the relations developed mathematically are
chosen for discussion and empirical relations are left
out. A more plausible general aquifer model based
equations are presented to show that the relationship
is direct only in electrolyte (conductance) dominated
aquifer case and inverse in matrix (resistance)
dominated aquifer. Few data points published already
are analyzed to show the efficacy of the equations.
-
-
-
Deep Electromagnetic Mapping Of The Serra Grande Aquifer For Optimum Groundwater Development On The Eastern Margin Of Parnaiba Basin, Piaui State, Brazil
Authors A.K. Mohamed, P.M. Abreu, M.A. Meju, S.L. Fontes, E.F. La Terra and C.R. GermanoA combined TEM -AMT survey was recently
carried out along three east-west transects at
the eastern margin of Parnaíba basin for
hydrogeological purposes. The MT data have
been processed using conventional tensorial
analysis technique and corrected for static shift
using dual-mode TEM data. Two-dimensional
regularis ed inversion of the TE and TM MT
data revealed distinct geoelectric patterns for
the three profiles. The contact between the
sedimentary and crystalline basement rocks
was clearly imaged in all the profiles. Grabenlike
structures are present in all cases and are
best developed about 20-30 km away from the
basin margin in the Monsenhor Hipólito and
Itainópolis transects. The graben structures are
considered to be the best places for drilling for
groundwater in this region. The 2-D resistivity
model for the Monsenhor Hipólito profile also
appears to define the position of a major fault
herein interpreted as the Picos fault, which
may have implications for groundwater
development in the area.
-
-
-
Desempenho Do Método Vlf Na Locação De Poços Em Terrenos Cristalinos De Uma Área Do Agreste Do Estado De Pernambuco, Brasil
Este trabalho trata da aplicação do método geofísico
VLF à prospecção de água subterrânea em terrenos
cristalinos do Agreste Meridional do Estado
de Pernambuco, Brasil, totalizando uma superfície
de 323km2, compreendendo parte dos municípios
de Jupi, Lajedo e Calçado, sendo a área delimitada
pelas coordenadas geográficas 8o38’52” e 8o48’09”
de latitude sul ; 36o16’27” e 36o26’45” W. Gr. O
equipamento utilizado foi o Wadi, fabricado pela
ABEM. Foram executados cerca de 75km de perfis
VLF transversais às estruturas fraturadas, normalmente
orientadas NW-SE, tendo sido locados e
perfurados 146 poços profundos durante o período
compreendido entre 1998 e meados de 2000. Os
resultados das locações através da técnica VLF
comparados com 91 locações usando critérios variados,
na mesma área e período desta pesquisa,
mostraram um melhor desempenho da metodologia
aqui utilizada no que se refere às vazões médias
obtidas. A vazão média obtida com a metodologia
VLF foi de 3635L/h, enquanto que com outros
critérios foi de 1595L/h. Além do mais, a percentagem
de poços secos (vazão inferior a 500L/h) foi de
4% para a locação com a ferramenta VLF, enquanto
que com outras ferramentas foi de 17%.
-
-
-
Efeito De Pequenas Distâncias Entre Os Eletrodos De Corrente Em Perfis Elétricos Com Arranjo Gradiente
More LessOver the years Gradient Arrays have been used in
resistivity profiling surveys over hard rocks in order
to locate fracture zones in both efficient and
inefficient ways, for groundwater prospecting. Many
of the unsuccessful applications are due to small
current electrode distance (AB). In this paper we
study the depth of investigation for the gradient array
and perform some numerical examples to show the
effect of the use of such small distance in the obtained
profiles. We see that when a small AB distance is
used, as soon as the location of the potential
electrodes changes, the depth of investigation of the
array is also changed, and so, a profile/sounding
curve is obtained, leading many times, in a
misinterpretation of the profile curves.
-
-
-
Electromagnetic Studies Of The Região Dos Lagos In Rio De Janeiro State - Brazil: Tectonic Framework And Groundwater Prospects
This work presents results of a geophysical survey
employing electromagnetic (magnetotelluric -MT and
time domain electromagnetics-TEM) techniques to
probe the upper crustal geoelectric structure aiming at
contributing to the geophysical knowledge of a poorly
understood area in southeastern Brazil. The survey
was carried out in Região dos Lagos - “The Lakes
Region” of Rio de Janeiro State, Brazil. A total of 34
MT-TEM soundings were located along two profiles
18 Km and 27 Km long both in the SE-NW direction
crossing orthogonally the observed regional faults
known from surface geology, aeromagnetic and
remote sensing images of the area.
The region is characterized by rocks predominantly of
pre-Cambrian age, fractured and altered gneisses and
sedimentary covers of quaternary age, described as
current and sub current sediments deposited in flood
plains and close to the coastal region. Twodimensional
geoelectrical models of the two profiles
evidenced some groundwater prospects at shallow
depths associated with quaternary sediments and
fracture zones. Anomalously conductive block at
depths between 3 and 6 Km may be related to
magmatic materials.
-
-
-
Ensaios De Resistividade Aplicados Em Estudos Hidrogeológicos Em Maceió, Alagoas - Brasil
More LessThe characterization of Barreiras/Marituba
Aquifer System, major source of water supply of
Maceió City, Alagoas State, Brasil, is an important
way to subsidy a sustainable usage and management
of groundwater. The tectonic and stratigraphycal
framework that was built using well logs and surface
geological information propose a model with a series
of grabens and horsts structures. To check and
calibrate this geological model were applied
geoelectrical surveys. Based on data obtained from
dipole-dipole electrical profiling and vertical
electrical souding it was possible to identify fault
zones and important stratigraphycal characteristics,
that confirms the proposed geological model.
-