Applied Geophysics Research Papers - Academia.edu (original) (raw)

We present a new method of regularization of seismic data using the finite offset common reflection source (FOCRS) traveltime approximation. This method fits curves of common reflection source to the reflection events and... more

We present a new method of regularization of seismic
data using the finite offset common reflection source (FOCRS) traveltime approximation. This method fits curves
of common reflection source to the reflection events and
stacks all the amplitudes in a given aperture. The stacked
amplitude, afterwards, is allocated to the time coordinate
in the trace to be interpolated. We applied this method to
three synthetic velocity models and the results showed
the capability for regularizing converted seismic waves in
stratified medium.

Monografies d'Ullastret 3, Museu d'Arqueologia de Catalunya, Ullastret, 2017

The Very Low Frequency Electromagnetic (VLF-EM) method, which enables surveying without contact with the ground, is suitable for ground surveys in a wide area and has been used in mapping geology and in mineral exploration for decades.... more

The Very Low Frequency Electromagnetic (VLF-EM) method, which enables surveying without contact with the ground, is suitable for ground surveys in a wide area and has been used in mapping geology and in mineral exploration for decades. The technique makes use of signal radiation from military navigation radio transmitters operating in the frequency range of 15-30 kHz. When the electromagnetic wave impinges on the surface it is both reflected back into the air and refracted into the earth. By measuring the shifted reflected magnetic field relative to the primary field, subsurface structures can be constrained. Freely and readily available primary signals anywhere around the earth make the VLF method very convenient and efficient for field data collection. Further, VLF data processing using digital linear filtering is quite accurate and very efficient in depicting the qualitative information about subsurface conductors, even though quantitative interpretation of VLF data is as complex as other EM data interpretation. In this study, various aspect of VLF-EM method such as basic theory, worldwide VLF transmitters, and quantities measured and a case study review of the integrated geophysical exploration for sulphide minerals In the Wadi Sa'al area, south Sinai in Egypt (only the VLF-EM method used in this study were review).

Levees are civil engineering structures built to protect human lives, property, and agricultural lands during flood events. To keep these important structures in a safe condition, continuous monitoring must be performed regularly and... more

Levees are civil engineering structures built to protect human lives, property, and agricultural lands during flood events. To keep these important structures in a safe condition, continuous monitoring must be performed regularly and thoroughly. Small rodent burrows are one of the major defects within levees; however, their early detection and repair helps in protecting levees during flooding events. A set of laboratory experiments was conducted to analyze the polarity change in GPR signals in the presence of subsurface voids and water-filled cavities. Ground Penetrating Radar (GPR) surveys using multi frequency antennas (400 MHz and 900 MHz) were conducted along an 875 meter section of the Lollie Levee near Conway, Arkansas, USA, to assess the levee's structural integrity. Many subsurface animal burrows, water-filled cavities, clay clasts, and metallic objects were investigated and identified. These anomalies were located at different depths and have different sizes. To ground truth the observations, hand dug trenches were excavated to confirm several anomalies. Results show an excellent match between GPR interpreted anomalies and the observed features. In-situ dielectric constant measurements were used to calculate the feature depths. The results of this research show that the 900 MHz antenna has more advantages over the 400 MHz antenna.

A Valley of Mummies was discovered recently by an Egyptian team at Bahariya Oasis, located about 380 km west of the pyramids. Four tombs were excavated, and inside them were found one hundred and five mummies (105), many of them... more

A Valley of Mummies was discovered recently by an Egyptian team at Bahariya Oasis, located about 380 km west of the pyramids. Four tombs were excavated, and inside them were found one hundred and five mummies (105), many of them beautifully gilded. These mummies, many sumptuously decorated with religious scenes, are the very best Roman-Period mummies ever found in Egypt. These remains are around 2000 years old, but they are in remarkable condition. A Ground-Penetrating Radar (GPR) had proved successful in detecting the cavities in resistive soil in which the mummies were found.The GPR survey conducted near the earlier-discovered tombs at Kilo-6 El-Bahariya to Farafra Oasis road is the focus of this paper. The GPR survey was conducted using the SIR-2000 attached to a 200 MHz monostatic antenna. The two areas to be surveyed were selected by the archaeologists in situ.Area one was 40 m × 40 m and Area two was 30 m × 15 m. A grid pattern survey in one direction; with one-meter profile s...

Dear researchers, Geoscience and the progress of technology can be put to the service of the environment for the improvement of human living conditions. In this context, the Laboratory of Geodynamics and Natural Resources (LGRN),... more

Dear researchers, Geoscience and the progress of technology can be put to the service of the environment for the improvement of human living conditions. In this context, the Laboratory of Geodynamics and Natural Resources (LGRN), Department of Geology, The Second Edition of Doctoral Days (2EJD), to be held on January 14 & 15, 2019 at the Faculty of Sciences Dhar El Mahraz, Sidi University Mohamed Ben Abdellah, Fez, Morocco. Research Ph.D. students will then have the opportunity to disseminate their research and share their experiences with other researchers. This edition will cover a wide range of topics in the fields of Geoscience and Natural Resources. Researchers who want to participate in the event Email: lgrn.doctoriales@gmail.com We look forward to meeting you at the Faculty of Sciences Dhar El Mahraz.

With this depletion in the groundwater table, there has been an overuse of water in the aquifers. Hence, in order to study the subsurface geology of the area and in order to investigate the aquifer presence in the area, we selected 8... more

With this depletion in the groundwater table, there has been an overuse of water in the aquifers. Hence, in order to study the subsurface geology of the area and in order to investigate the aquifer presence in the area, we selected 8 points namely S1 to S8 for Vertical Electrical Soundings (VES1 to VES8 respectively). Using this method, resistivity data was collected, interpreted and aquifer strata were explored which is the main aim here. Schlumberger electrode configuration was used here. IGIS DDR3 DC resistivity meter was used to carry out the exploration in Chapabandi mouza, Durgapur, District Burdwan, West Bengal having lateral extension of 600m (AB). Hence the penetration depth of current was nearly 160-170m. It was established that a deeper claysand stratum exists comprising of medium to fine grained sand at points S2, S4and S7 where drilling up to 150-160m was recommended.

This brief review presents the international approaches to assessment of the content of geotaxis impurities (residual solvents and various inorganic and organic impurities) in pharmaceuticals. Nowadays, it has become necessary to provide... more

This brief review presents the international approaches to
assessment of the content of geotaxis impurities (residual solvents
and various inorganic and organic impurities) in pharmaceuticals.
Nowadays, it has become necessary to provide not only purity
profile but also impurity profile of a particular pharmaceutical
product because of national and international regulations. These
aspects along with significance of the quality, efficacy and safety
of pharmaceuticals, including the source of impurities, kinds
of impurities, control of impurities and regulatory aspects are
discussed.

Recently, encouraging results have been obtained to estimate hydraulic conductivity in unconsolidated sediments from induced polarisation (IP) measurements. The work focussed on laboratory experiments in order to establish semi-empirical... more

Recently, encouraging results have been obtained to estimate hydraulic conductivity in unconsolidated sediments from induced polarisation (IP) measurements. The work focussed on laboratory experiments in order to establish semi-empirical relationships between complex electrical conductivity and hydraulic parameters. Although field studies are certainly important to evaluate the feasibility of the method in practice, only a limited number of case histories have

Metamorphic processes, leading to mineralogical and structural changes of the rocks in response to physical (pressure, temperature) and chemical conditions, can be associated with the development of sin-metamorphic or post-metamorphic... more

Metamorphic processes, leading to mineralogical and structural changes of the rocks in response to physical (pressure, temperature) and chemical conditions, can be associated with the development of sin-metamorphic or post-metamorphic fractures. The post-metamorphic ones are directly related to tectonic stress. In addition, tectonic stress may cause the reorientation of minerals on a direction perpendicular to the stress direction, generating foliations (schistosity).
This paper presents a structural analysis of the pre-Alpine metamorphic basement and its relations with the sedimentary cover by using geophysical data recorded in an exploration well located in the North Dobrogea Promontory (Romania). The analysis was based on Quad-Combo wireline logs, spectral gamma ray, sonic cross-dipole and borehole electrical imaging data. The imaging analysis allowed the identification and characterization of metamorphic foliations, sedimentary bedding, natural fractures and the determination of tectonic stress orientation. A brittleness index was computed by means of elastic parameters derived from density and sonic compressional and shear logs. Also, a fracture intensity characterization by using fracture area per volume of rock was conducted. The integration of geophysical logs with mud logging and drilling data allowed us to carry out a detailed analysis of the metamorphic basement in the studied area.

The MT interpretation procedure begins with a set of sounding data in the frequency domain. The overall quality of these data can be variable both as a function of frequency and location. Many simple interpretation procedures, such as the... more

The MT interpretation procedure begins with a set of sounding data in the frequency domain. The overall quality of these data can be variable both as a function of frequency and location. Many simple interpretation procedures, such as the assessment of static distortion, act directly on the sounding data. A number of response characteristics, such as the location (in frequency) and number of turning points, are important to the interpretation. Localised scatter (noise) in the response estimates can produce false gradients which degrade the quality of the inferences made from the data. This study considers how the D + solution can be used to process the raw sounding data to provide a number of interpretational advantages. Although the D + solution has strict formal roots in 1D inverse theory, it is used here simply to enhance those data attributes, particularly that of physical validity, which lead to a more meaningful assessment of data characteristics. The data considered are 84 broadband array soundings from the Paraná basin, Brazil. The advantages provided by the D + processed data set are demonstrated by using the raw and processed data in two main interpretational procedures. The first procedure concerns the ability of the data to provide quantitative assessments of the influence of static distortion. The second procedure concerns the application of transform methods which attempt to recover a resistivity/depth or reflectivity profile directly from the sounding data.

An inexpensive infrared beam barrier and proximity detector has been designed and analyzed using solid state discrete components. The result showed that a security system using infrared technology is possible and viable where the breaking... more

An inexpensive infrared beam barrier and proximity detector has been designed and analyzed using solid state discrete components. The result showed that a security system using infrared technology is possible and viable where the breaking of an infrared signal by objects including humans passing or wandering within restricted premises can be effectively monitored. The design was achieved with the help of IR Module and LEDs, a 555IC timer which oscillates at about 38kHz, a regulating IC which regulates a 9V dc to 5V, transistors, and variable resistors that contribute to the strength of the IR signal generated together with some other passive components. The completed device designed only requires an external power supply when the relay is to be used in triggering an external alarm or switching of bulbs. The design results also showed that the 555IC timer can be used to produce accurate timing ranging from microseconds to hours if the variable resistors can be reduced while the capacitors across it is increased. More so, it was evident from this study that the infrared which has a very small wavelength in micrometers as recorded in the electromagnetic spectrum, can be optimized to travel farther distances of over 250cm.

Stratigraphy and the oil industry are intricately intertwined and have been so ever since the early days of hydrocarbon exploitation. Stratigraphic understanding forms the basis for all upstream activity from basin exploration through... more

Stratigraphy and the oil industry are intricately intertwined and have been so ever since the early days of hydrocarbon exploitation. Stratigraphic understanding forms the basis for all upstream activity from basin exploration through field evaluation to reservoir development and production. In the quest for hydrocarbons, both the exploration and exploitation programs can be greatly enhanced by applying stratigraphic analysis. This technique provides the explorationist with the capability to recognize, discover and evaluate new hydrocarbon reservoirs and to reduce the risk in management's decision-making.
Stratigraphic approach to hydrocarbon studies can make use of high-resolution biostratigraphic and pale bathymetric data, well-log signatures and seismic-reflection profiles, and well core data to determine the lithostratigraphy, lithofacies, depositional sequences, and the sequence boundaries.
This study explores the integration of seismic and well-log data for stratigraphic studies. The identification of depositional environments from well logs is based on the principle that well log responses are related to changes in thickness, texture, grain size, and lithology along the well path, while the relection pattern recorded on seismic sections can be interpreted in term of depositional environment and lithofacies.
A case study of the Sequence Stratigraphy of Akos Field in the Coastal Swamp Depobelt of the Niger Delta was considered. From which it can be concluded that the integration of seismic and well log data for stratigraphic studies is a valuable tool for oil and gas exploration.

The paper presents a numerical algorithm that performs accurate lithology corrections for thermal (CNL/TNPH, CNL/NPHI) and epithermal (SNP) neutron logs, in the whole range of porosities normally encountered in practice. It is known that... more

The paper presents a numerical algorithm that performs accurate lithology corrections for thermal (CNL/TNPH, CNL/NPHI) and epithermal (SNP) neutron logs, in the whole range of porosities normally encountered in practice. It is known that neutron logs respond not only to a formation’s true porosity, but, to some extent, also to its lithology (the so-called "matrix effect"). Because the matrix effect is nonlinear and varies with true porosity, which is unknown beforehand, an iterative process is needed in order to carry out proper lithology corrections and obtain formation's porosity. The relationships between measured neutron porosity and true porosity for the common reservoir lithologies (sandstones, limestones and dolomites), at different formation water salinities, are approximable via suitable regression polynomials. Nonlinear neutron responses thus expressed are combined with the responses of density and sonic velocity logs, together with the volumetric unity constraint, into a system which is solved using a Newton-Raphson root-finding routine. The algorithm, implemented as a set of Matlab™ codes, provides optimal petrophysical models for the interpretation of neutron-density-sonic log suites and is easily adaptable in order to include additional linear or nonlinear log response equations. A case study regarding its applicability is also presented in the paper.

Laboratory and field measurements were made in a study of a small number of chromite deposits in the Josephine ultramafic complex of northwest California, to examine their physical properties and to search for possible diagnostic... more

Laboratory and field measurements were made in a study of a small number of chromite deposits in the Josephine ultramafic complex of northwest California, to examine their physical properties and to search for possible diagnostic geophysical signatures. Though the sample was small, the results show that no single geophysical method gives unequivocal identification of buried massive pods of chromite, but that a combination of gravity, magnetics, and seismics, and complex resistivity might be used to explore successfully if used in a systematic fashion. Some of the geophysical signatures appear to be secondary or associative in nature, raising the possibility that a specific method or combination of methods might have to be modified for application in
an area other than where they were developed.

The study area is located in the northern and western parts of Moldavian Platform, the oldest platform unit of the Romanian territory and representing the margin of the East European Platform. Two hydrocarbon systems are recognized in the... more

The study area is located in the northern and western parts of Moldavian Platform, the oldest platform unit of the Romanian territory and representing the margin of the East European Platform. Two hydrocarbon systems are recognized in the Moldavian Platform: a thermogenic system of Paleozoic age and a biogenic system of Miocene age. The Miocene biogenic system comprises significant natural gas fields (including dry gas with more than 98% methane), reservoired especially in Sarmatian (late Middle Miocene) deposits, where suitable conditions for accumulation and sealing are encountered. The Sarmatian stage was marked by permanent changes of the sedimentary conditions, passing from a predominantly marine environment to a transitional one, of deltaic type with lacustrine-continental influences. The gas accumulations are usually hosted in sands/sandstones (observed as good seismic reflectors with continuous or discontinuous character) that pinch out forming lithostratigraphic traps. The sand beds or sand bodies formed during the deltaic construction, especially when they overlap and alternate with pelitic sequences, offer the most favorable settings for such accumulations.
The integrated analysis of recent geophysical well logs (conventional logs and high-resolution electrical imaging logs) and seismic reflection surveys, together with mud logging data and well flow test results, allow a better characterization of the Sarmatian deposits, particularly the gas reservoirs, from the study area. The correlation of three exploration wells along a NW–SE profile indicates that a low-energy, fine-grained depositional environment is developing towards SE, with a prevalence of claystones and with fewer sand reservoirs, if any. This may reflect a deltaic transition from distributary channels and mouth bar sands towards prodelta offshore silts and muds. The processed electrical imaging data recorded in the northernmost exploration well show two dominant dip azimuths (142 and, subordinately, 218 degrees) in the shale intervals. Most likely, these indicate NW to SE and NE to SW sediment paleotransport directions, related to seaward delta progradation. The electrical imaging results also reveal the presence of two high-angle faults (48–54 degrees dip values), which might have provided pathways for gas migration from deeper levels up to shallower Sarmatian reservoirs.

In contrast to the use of marine seismic reflection techniques for reservoir-scale applications, where seismic inversion for quantitative sediment analysis is common, shallow-water, very-high-resolution seismic reflection data are seldom... more

In contrast to the use of marine seismic reflection techniques for reservoir-scale applications, where seismic inversion for quantitative sediment analysis is common, shallow-water, very-high-resolution seismic reflection data are seldom used for more than qualitative reflection interpretation. Here, a quantitative analysis of very-high-resolution marine seismic reflection profiles from a shallow- water (<50 m water depth) fjord in northern Norway is presented. Acquired using Sparker, Boomer, and Chirp sources, the failure plane of multiple local landslides correlates with a composite reflection that reverses polarity to the south. Using a genetic algorithm, a 1D post-stack acoustic impedance inversion of all three profiles is performed, calibrating against multi-sensor core logger (MSCL) data from cores. Using empirical relationships the resulting impedance profiles are related to remote sediment properties, including: P-wave velocity; density; mean grain size; and porosity. The composite reflector is consistently identified by all three data sources as a finer-grained (by one Phi), lower density (c. 0.2 g/cm3 less than background) thin bed, with an anomalous low velocity zone (at least 100 m/s lower than background) associated with the polarity reversal to the south. Such a velocity contrast is consistent with an accumulation of shallow free gas trapped within the finer- grain, less permeable layer. This study represents the first application of acoustic impedance inversion to very-high-resolution seismic reflection data and demonstrates the potential for directly relating seismic reflection data with sediment properties using a variety of commonly used shallow seismic profiling sources.

Depositional environments are characterized by their sedimentary lithology, sedimentary structures, paleocurrent patterns and fossils. Sedimentary facies are bodies of sediment that originate simultaneously in adjacent depositional... more

Depositional environments are characterized by their sedimentary lithology, sedimentary structures, paleocurrent patterns and fossils. Sedimentary facies are bodies of sediment that originate simultaneously in adjacent depositional environments. Such environments can be reconstructed using core data, well log information, and outcrops, and other available geologic information. In a study of four oil wells, depositional environments were inferred from the gamma ray log shapes identified on the gamma ray log motifs in combination with the density-neutron trends principle and sonic log high or low spikes. The Multi-Regressive Graph-Based Clustering approach was also used to compliment interpretations. The results obtained show that sand bodies that display an aggradational stacking pattern may be inferred to be channel sand deposits, regressive barrier bars, prograding delta deposits, and alluvial/ fluvial channel, or of transgressive shelf sand. A combination of Multi Regression Graph –Based Clustering and well log motifs has thus been shown to be a reliable tool in depositional environment reconstruction and lithofacies prediction.

2D seismic refraction data, from seven traverse lines, were used to investigate subsurface geology in the Appollonian Formation of the onshore Tano Basin of Ghana. Tano Basin is one of the four basins of Ghana and the most important one... more

2D seismic refraction data, from seven traverse lines, were used to investigate subsurface geology in the Appollonian Formation of the onshore Tano Basin of Ghana. Tano Basin is one of the four basins of Ghana and the most important one when it comes to oil potential of Ghana. The survey covered approximately a total area of about 113,000 m 2. With the exception of one traverse line which had the length of 60 m, each of the remaining traverse lines had a length of 120m. The results from the data analysis indicated that, the surveyed area is underlain by three geological units although results from two traverse lines revealed two geological units. The P-wave velocity of the first layer ranges between 335.00-468.00 m/s and the average velocity of 391.57 m/s. It has a thickness range of 5.0-27.5 m with an average thickness of 16.25 m. The layer is interpreted as a weathered layer and consist of soil and dry loose sand which might be formed as beach deposit. The second layer has P-wave velocity range of 590.00-1133.00 m/s and the average velocity of 881.71 m/s. The layer thickness ranges between 14.5-31.0 m and the average of 25.80 m. The layer may consist of unconsolidated water-saturated sand and clay. The last layer detected by this survey has P-wave velocity range of 1068.00-2724.00 m/s and the average of 2074.20 m/s. The layer is interpreted as the bedrock underlining the surveyed area. The layer may consist of gravel, sandstone and limestone.

Since 2016 the Department of Culture and Civilization History at the University of Bologna has been conducting a study under the direction of Giuseppe Lepore and Enrico Giorgi, on the 3rd insula of the Roman Hellenistic Quarter of... more

Since 2016 the Department of Culture and Civilization History at the University of Bologna has been conducting a study under the direction of Giuseppe Lepore and Enrico Giorgi, on the 3rd insula of the Roman Hellenistic Quarter of Agrigento. The tradition of studies starts from the latter part of 1800, but many questions remain. One of these concerns the original phases of the urban planning ascribed to the pre-roman age (VI-V century BC) of which there are currently few traces. We have tried to give attention to the preventive archaeology through a methodological and innovative approach with surveying techniques and non-invasive investigation of the subsoil (coordinated by Federica Boschi). The investigation carried out with the GPR method – where possible – involved all the houses of the insula III and the stenopòs III for a total surface area of around 5600 square meters. With the geomagnetic method in gradiometric configuration was carried out an investigation in an open country spaces never explored before again. Both methods proved to be quite effective, although some limitations were found during the acquisition phase due to disturbances caused by logistic impediments (tight spaces inside the already excavated houses; metal bounding fences and trees in pasture spaces) and the
physical characteristics of the site. These factors have partially affected the interpretation of the data, making it more problematic. Despite the difficulties the results obtained have given us important data that will contribute to the wider debate on the evolution of the housing area.

Small, low cost Autonomous underwater vehicles (AUVs) provide ideal platforms for shallow water survey, as they are capable of unmanned navigation and can be programmed to acquire data at constant depth, or constant altitude above the... more

Small, low cost Autonomous underwater vehicles (AUVs) provide ideal platforms for shallow water survey, as they are capable of unmanned navigation and can be programmed to acquire data at constant depth, or constant altitude above the seabed. AUVs can be deployed under most sea states and are unaffected by vessel motions that often degrade sonar and magnetometer data quality. The integration of sonar and magnetometer sensors on AUV’s is challenging, however, due to limited payload and strong magnetic fields produced by the vehicle motor.
In this study, a Marine Magnetics Explorer Overhauser magnetometer was mated to a portable AUV (OceanServer Iver2) creating the first practical AUV- deployed magnetic survey system. To eliminate magnetic interference from the AUV, the magnetometer was tethered to the AUV with a 5 m tow cable, as determined by static and dynamic instrument testing. The results of the magnetic tests are presented, along with field data from a shallow water test area in Lake Ontario near Toronto, Canada. AUV-acquired magnetic survey data were compared directly with a conventional boat-towed magnetic survey of the same area. The AUV magnetic data were of superior quality despite being collected in rough weather conditions that would have made conventional survey impossible. The resulting high-resolution total magnetic intensity and analytic signal maps clearly identify several buried and surface ferrometallic targets that were verified in 500-kHz side- scan sonar imaging and visual inspection by divers.

The electromagnetic profiling and Vertical Electrical Sounding (VES) data were acquired from some communities in the Twifo-Hemang Lower Denkyira District of the Central region of Ghana, in order to determine zones of high groundwater... more

The electromagnetic profiling and Vertical Electrical Sounding (VES) data were acquired from some communities in the Twifo-Hemang Lower Denkyira District of the Central region of Ghana, in order to determine zones of high groundwater potentials and to recommend suitable sites to drill boreholes for community water supply. The research reported here covered three communities namely; Esukese Ekyire, Kwanyarko. First the electromagnetic measurements were carried out, qualitative interpretations of the data were carried out and weathered rock zones were identified. Then the VES measurements using Schlumberger array were conducted at points on the electromagnetic traverse that displayed weathered zones. ZONDIP1D software was used in creating 1D sounding curve models of geological subsurface structures beneath the sounding points. Results of the modelling suggest that the communities are underlain by three to four geological layers. Interpretations of the 1D inversion of the VES data provide the resistivities and thicknesses of subsurface layers. On the basis of resistivity values and thicknesses of the layers in the 1D models, sites were recommended to drill boreholes for community water supply.

In this study, we assessed recent GOCE-based Global Geopotential Models (GGMs) and EGM2008 in Niger. The combined GGMs EIGEN_6C4, GECO and EGM2008 were evaluated up to their maximum degree and order (d/o) 2,190 to select the one for... more

In this study, we assessed recent GOCE-based Global Geopotential Models (GGMs) and EGM2008 in Niger. The combined GGMs EIGEN_6C4, GECO and EGM2008 were evaluated up to their maximum degree and order (d/o) 2,190 to select the one for gravity database densification. The following pure satellite GGMs were assessed for the modelling of the long and medium wavelengths in geoid computation: GGM05G, ITU_GGC16, EIGEN_6S4v2 and the fifth releases from
direct (DIR5), space-wise (SPW5) and time-wise (TIM5) approaches. The GGMs are compared to terrestrial gravity data and geoid heights from GNSS/Levelling points before and after applying spectral enhancement method (SEM) by residual terrain model (RTM) for combined models and by RTM and the coefficients of selected combined GGM for pure satellite models. The agreements of combined GGMs with terrestrial gravity data and GNSS/Levelling points, in terms of root mean
square (RMS) are about 4.88 to 5.02 mGal and 0.14 to 0.16 m, respectively. EIGEN_6C4 was selected as it showed the best
performance in terms of geoid height differences and the probability of 3-sigma rule for gravity anomaly differences. At d/o 200, DIR5 showed a good agreement with terrestrial gravity data (5.04 mGal) and GNSS/Levelling points (0.15 m) after applying SEM, it was then retained. All GOCE-based models exhibited a good performance in long and medium wavelengths confirming the good recovery of the gravity field by the spatial gravity mission in these spectral bands.

Introducing and applying an appropriate strategy for reservoir modeling in strongly heterogeneous and fractured reservoirs is a controversial issue in reservoir engineering. Various integration approaches have been introduced to combine... more

Introducing and applying an appropriate strategy for reservoir modeling in strongly heterogeneous and fractured reservoirs is a controversial issue in reservoir engineering. Various integration approaches have been introduced to combine different sources of information and model building techniques to handle heterogeneity in geological complex reservoir. However, most of these integration approaches in several studies fail on modeling strongly fractured limestone reservoir rocks of the Zagros belt in southwest Iran. In this study, we introduced a new strategy for appropriate modeling of a production formation fractured rock. Firstly, different rock types in the study area were identified based on well log data. Then, the Sarvak Formation was divided into nine zones, and the thinner subzones were used for further fine modeling procedure. These subzones were separated based on different fracture types and fracture distribution in each zone. This strategy provided sophisticated distribution of petrophysical parameters throughout the grids of the model, and therefore, it can handle strong heterogeneity of the complex reservoir. Afterward, petrophysical parameters were used to produce an up-scaled 3D gridded petrophysical model. Subsequently, maps of petrophysical properties were derived for each zone of the Sarvak Formation. Evidences achieved in this study indicates Sarvak Formation zone 2 as the target production zone with better performance of reservoir rock and the southwestern part of the field as area of maximum porosity.