Chairman: prof. RADU BOTEZATU, corresponding member of the Academy
COMPENSATION OF THE PHASE SHIFT OF ELECTRICAL FILTERS
AND ITS INFLUENCE UPON WAVELET PROCESSING
V. BARDAN, C. POPESCU, M. ATANASIU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents examples, on synthetic and real data, of the influence
of the phase shifts introduced by electrical filters (during the recording
of the seismic signal) on wavelet processing and demonstrates the necessity
and possibility of the numerical compensation of those phase shifts.
Key words: electrical filters, phase shift, wavelet processing
f – k FILTERING FOR REVERBERATION ATTENUATION
C. POPESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
Reverberation attenuation is done in f – k domain by means of a band-phase
filter which is applied on NMO corrected seismograms. After this step, inverse
2D Fourier transform is applied and seismograms are inverse NMO corrected.
Key words: reverberation, band-pass filter, f – k domain, 2D Fourier
transform, inverse NMO.
GENPLAN
E. DANANAU, C. CEAPRAZ, D. RUSU, MIHAELA CEAPRAZ, I. CHISCAN, S. TUPA
Enterprise of Geological and Geophysical Surveys, Bucharest
The plane waves have been used, after Rieber (1937), in the years 1950 – 1960
and were then abandoned.
The GENPLAN method (from GENerated PLANe waves) uses, as the name indicates,
plane waves in the seismical prospecting.
The paper presents the principles for choosing the field parameters and some
preliminary results.
Key words: plane waves, simulated plane waves, generated plane waves (GENPLAN)
THE MEASUREMENT ERROR OF SEISMIC SIGNAL
E. DANANAU, I. ZIHAN, I. GAUZIN, I. CHISCAN
Enterprise of Geological and Geophysical Surveys, Bucharest
In the paper, the measurement error of the seismic signal in the seismic
digital recorders is estimated, taking into account the correct operating of
the last.
The correlation between the error and the magnitude of the seismic noise is
studied together with implications upon the acquisition parameters in the field.
Key words: measurement, error, digital recorder.
HOMOMORPHIC DECONVOLUTION (HD)
C. POPESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
This paper deals with various applications of HD (Oppenheimer) in seismic
data processing. It will be centered on removal of reverberations in marine
records and computer simulations will be presented.
Key words: homomorphic system, cepstrum, phase unwrapping, linear filtering
in cepstral domain
ASPECTS OF STRUCTURAL MODELING IN SEISMICAL PROSPECTING
LILIANA BADESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents an iterative procedure based on modeling methods which intended to increase the accuracy of interval velocity and geometrical parameters of seismic sections.
Key words: iterative method, modeling, interval velocity
ASPECTS OF INVERSE PROBLEM IN SEISMIC PROSPECTING
M. CRISTEA
Enterprise of Geological and Geophysical Surveys, Bucharest
In seismic prospecting, as in all other geophysical methods, "inverse
problem" means to determine the structure of the interior of the earth
from data obtained at the surface.
This paper is a review of several methods to solve this problem.
APPLICATION OF THE RADON TRANSFORM IN PROCESSING OF SEISMIC DATA
N. MOLDOVEANU, C. CALOENESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
The radon transform is a very valuable mathematical tool for signal processing
and it is used in different areas as seismology, tomography, radiography, etc.
This paper presents the Radon transform and its properties, numerical implementation
of this and possibilities for application of Radon transform in seismic data
processing.
Key words: Radon transform, processing, signals, numerical, implementation,
seismics.
ON THE IMPLEMENTATION OF 3D MIGRATION
V. BARDAN, M. ATANASIU, V. BUZULOIU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents an algorithm for the implementation of 3D migration in
the ? – kx – ky domain and shows its advantages over the two-steps
migration.
An example of the application of this algorithm on synthetic seismic data is
included.
Key words: seismics, algorithm, 3D migration.
A GRAVITY-MAGNETICS MODEL OF THE BABADAG-SINOE AREA
VL. ROSCA, GEORGETA BESUTIU, GH. IONESCU
Institute of Geology and Geophysics, Bucharest
Petrophysical data concerning the main formations of the north-eastern Central
Dobrogea as well as the northern part of the Pecineaga-Camena fault line, have
been used for building up a gravity-magnetics model based on upright rectangular
prismatic bodies. The model suggests that in the basement of the green shists,
rocks different from the Altîn-Tepe series are present.
Key words: gravity – magnetics model, Dobrogea.
WELL LOG DATA AS A TOOL IN DEPOSITIONAL PROCESSES ANALYSIS – AN EXAMPLE
R. BOTEZATU, KIM ZU HEN
The paper is presented in extenso in this issue, page 45.
A SIMULATION MODEL OF THE AGIGHIOL-NICULITEL FAULTS SYSTEM
OF THE BASEMENT (NORTHERN DOBRUDJA)
R. BOTEZATU, CARMEN DUMITRESCU
University of Bucharest, Faculty of Geology and Geography, Geology and Geophysics
Dept.,
Bucharest
On the basis of the embodiment of gravity, geological and petrophysical information,
a simulation model of the basement structure in the Triasic zone from Northern
Dobrudja was built. This model represents a system of faults having in the
main the same direction as the chief tectonic accidents of this geological
unit. Its existence suggests that this one has controlled the great thickness
of the Mosozoic-Palaeozoic sediments exceeding 3,000 meters and, generally,
the all tectono-magmatic evolution of the region.
Key words: simulation model; fault; faults system; basement, sedimentary cover;
structure.
SEISMIC RESEARCHES ON THE ROMANIAN BLACK SEA CONTINENTAL PLATFORM
V. VARODIN, V. CHISCAN, A. POPESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
The seismic prospecting on the Black Sea continental platform was developed
during two stages by reconnaissance and semi-detail profiles, coverage 600%,
1200% (1969 – 1974) and semi-detail and detail 3D profiles, coverage
2400%, 4800% (1980 – 1984). The processing of registered data leads to
structural and stratigraphical studies. The Hilbert transform analysis of the
analytic signal and seiscrops were performed for zones of peculiar interest.
Key words: 3D-profiles, Hilbert transform, analytic signal, seiscrop.
EQUIPMENT FOR THE MODELLING OF 3D SEISMIC DATA ACQUISITION
V. BUZULOIU1, A. GHEORGHE2, M. ATANASIU1
1Enterprise of Geological and Geophysical Surveys, Bucharest
2Polytechnic Institute, Bucharest
We describe the hardware and the programs for the acquisition of the (physical-)
simulation data needed in the development of 3D algorithms for the processing
of actual seismic data. the experiments were made with ultrasonic waves propagating
in air. The data were transferred to a SEL-32 computer. The paper also describes
future steps in the development of the equipment and its possible uses for
other applications.
Key words: physical model, seismic, microsystem.
SEISMIC FOR PRODUCTION DEVELOPMENT
N. MOLDOVEANU, M. POPESCU, V. DUMITRESCU, M. ALEXANDRESCU
Enterprise of Geological and Geophysical Surveys, Bucharest
The technologic advances in seismic prospecting allows the use of this technique
in the development of production.
The high resolution processing applied on some lines of the Calacea structure
demonstrates this possibility.
Key words: technologic advances, seismic processing, development production.
THE DETERMINATION OF ELASTIC SOIL-PARAMETERS BY IN-SITU MEASUREMENTS
V. RAILEANU, FL. RADULESCU, A. POMPILIAN, A. BALA
Center For Earth Physics and Seismology, Bucharest – Magurele
The paper presents field techniques for determining the compressional and
shear wave velocities both at surface (shear wave refraction method) and in
boreholes (downhole and crosshole methods).
The velocities determined in this way permit the computation of the elastic
parameters (shear modulus, Young modulus and Poisson ratio), commonly used
for earthquake response calculations.
There are analyzed the results of the studies carried out in the same site
from south Transylvania.
Key words: compressional and shear wave, velocity, cross-hole and downhole
methods, Poisson ratio, shear modulus, Young modulus, shear sources
PETROPHYSICAL ROCK PATTERN RECOGNITION: A NEED IN THE INTERPRETATION OF
WELL LOGGING DATA
V. NEGOITA
Oil and Gas Research and Design Institute, Campina
In order to improve well logging data interpretation a pattern recognition
approach based on graphs relating porosity, formation factor, tortuosity and
cementation exponent is set forth.
Key words: pattern recognition, rock petrophysics, well logging data
SOME APPROACHES FOR IMPROVING WELL LOGGING METHODS OF SUPER-DEEP WELLS
(10,000 M)
V. NEGOITA
Oil and Gas Research and Design Institute, Campina
This work is attempting to present the new problems aroused by the well logging
investigations of super-deep wells (10,000 m).
The hole diameter, the drilling fluid type, the temperature and pressure conditions,
as well as the rock petrophysical characteristics are analyzed, simultaneously
pointing out some new approaches in this respect.
Key words: well logging investigation, super-deep wells.
CONTRIBUTIONS TO THE APPLICATION OF THE PALEOMAGNETIC
METHOD TO THE CHRONOSTRATIGRAPHIC STUDY OF COAL DEPOSITS
SORIN RADAN, MARIA RADAN, I. ANDREESCU, N. TICLEANU
Institute of Geology and Geophysics, Bucharest
On the basis of the paleomagnetic investigation of some Sarmatian (Comanesti
Basin) and Pliocene (NW Oltenia) coal bearing formations their magnetic polarity
has been determined and integrated in the reference chronopaleomagnetic columns.
These data, corroborated with those on paleofauna and paleoflora, led to some
useful chronostratigraphic information regarding the coal deposits in the two
above-mentioned areas of Romania.
Key words: paleomagnetism, biostratigraphy, magnetostratigraphy, coal deposits,
Sarmatian Pliocene.
REMOTE SENSING AS APPLIED TO GEOLOGICAL STRUCTURAL PROBLEMS OF THE APUSENI
MTS
ANCA MARIA VIJDEA
Institute of Geology and Geophysics, Bucharest
The paper presents the main results of the geological interpretation for
remote sensing data: lineaments map, rose diagrams, maps of lineaments concentrations.
The data have been obtained during the analyses of satellite images taken from
the Apuseni Mts. Area.
Special attention has been paid to the main trend of the lineaments, many of
them being correlated with tectonic disjunctive elements partially outlined
by the conventional geological and geophysical mapping in the region. The main
circular features depicted on the images often represent the effects of the
volcanic and subvolcanic structures too.
Key words: remote sensing, satellite image, lineaments; fractures, circular
featuares, volcanic structures
3D SEISMIC PROCESSING IN THE TAZLAU AREA
N. MOLDOVEANU, LILIANA BADESCU, ELENA CHISCAN, C. CAPRA,
MARLEN MARIAN, I. MIHALACHE, I. ZIHAN, ST. ALBU
Enterprise of Geological and Geophysical Surveys, Bucharest
The paper presents the peculiarities of 3D seismic data processing, the implementation
of 3D migration and the display of results for network of multiple coverage
seismic lines.
The implications arising in data acquisition and interpretation are also discussed.
Key words: seismic, multiple coverage, 3D migration
QUANTITATIVE ESTIMATION OF SEDIMENTARY BASINS SUBSIDENCE.
CONSIDERATIONS ON THE TRANSYLVANIAN BASIN
C. CRANGANU
A. I. Cuza University of Iasi, Faculty of Biology – Geography – Geology,
Geological and Geophysical Engineering Department, Iasi
Two main mechanisms of subsidence are discussed: the stretching mechanism
and the thermal contraction mechanism. The role of eustatic variations in the
subsidence of the sedimentary basin is pointed out.
Finally, some considerations on the Transylvania basin subsidence are made.
Key words: subsidence, stretching, thermal contraction, eustatic variations
DIGITAL EQUIPMENT FOR ACOUSTIG LOGGING DSC – 2
V. VARODIN, V. NEGRESCU, H. POPESCU, L. POP
Enterprise of Geological and Geophysical Surveys, Bucharest
DSC – 2 is a numeric equipment used for measurement of acoustic velocity
distribution across the weathered layers.
The equipment allows velocity measurements in the 0 – 100 ms travel time
range for the determination of velocity variations within the weathering layers.
The information acquired is used in the processing of field data.
Key words: measurements, velocity variations, weathering layers.
AN EFFICIENT AND NECESSARY INSTRUMENT IN GEOPHYSICAL
WELL-LOGGING OF LITTLE DEEP DRILL HOLES
A. BALA
Center for Earth Physics and Seismology, Bucharest – Magurele
The paper presents a portable system for geophysical well logging in drill
holes up to 200 m deep. The system offers the possibility for density rock
measuring "in situ" and also for some combined electrical methods.
The use of this system was tested in gamma-ray logging.
Some field results are discussed.
Key words: portable system for geophysical well logging, rock density, electrical
survey, gamma-ray logging.
REMOTE SENSING APPLICATION TO THE IDENTIFICATION OF COVERED GEOLOGICAL
STRUCTURES
V. VAJDEA, M. SANDULESCU, C. NITICA, DANA FEKETE
Institute of Geology and Geophysics, Bucharest
The interpretation of the results of the LANDSAT satellite images in the
development area of the central South Carpathians and of the northern segment
of the East Carpathians have led to new information on their structural models.
The possibilities and limitations of remote sensing when tackling such studies
have also been established.
Key words: remote sensing, LANDSAT images, fractures, grabens, intrusive bodies.
APPLICATIONS OF THE INTERPRETATION OF GEOPHYSICAL LOGS
FOR HYDROGEOLOGICAL PROBLEMS IN THE PANNONIAN DEPRESSION
C. MIHAIL
Enterprise of Geological and Geophysical Surveys, Bucharest
New data were obtained concerning the thickness and structure of the geothermal
aquiferous from the Upper and Lower Pannonian by interpreting the geophysical
logs of about 1,000 wells.
The basis was thus elaborated for the estimation of geothermal water storages
in Pannonian and the areas of maximum efficiency for the hydrogeological wells
were outlined.
Key words: aquiferous, geophysical log, geothermal water storages.