SEG International Conf.on Engineering Geophysics Part One

SEG International Conf.on Engineering Geophysics Part One

Postby salsinawi » Sun Sep 04, 2016 4:29 pm

SEG International Conf.on Engineering Geophysics Part One
,[color=#40BF80] Al Ain, United Arab Emirates, 15-18 November 2015 [/color]

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Keynote Speech: Adapting the oil exploration model to contaminated site characterization: A cost benefit perspective

Authors: John H. Bradford
Boise State University, Boise, ID, USA

For decades, the oil industry has employed a working model for hydrocarbon exploration in which large-scale geophysical surveys are undertaken prior to a second phase of intensive, targeted drilling. This latter phase may be conducted in conjunction with further focused geophysical studies. The geophysical surveys provide lateral coverage and continuity that are used to drive placement of drilling locations. The reason for this approach is simple: wells are expensive relative to geophysical surveys. Also, practical limits on lateral coverage preclude optimization of exploration targets based on well information alone.

Reliability maps for seismic tomography

Authors: Thomas Fechner*
Geotomographie GmbH, Neuwied, Germany;
Authors: Solomon Ifeanyi Ehosioke
University of Goettingen, Germany;
Authors: Sonja Mackens, Lutz Karl
Geotomographie GmbH, Neuwied, Germany;
Authors: Daryl Tweeton
GeoTom LLC, Apple Valley, Minnesota

Seismic borehole tomography has become a standard method and is routinely used for the detection of karstic phenomena and the delineation of geological structures. Seismic tomography is believed to be the seismic method promising highest accuracy and reliability. Remaining uncertainties due to a non-zero residual travel time fit during data inversion are often neglected. However, data quality has a significant influence on the accuracy of a travel time pick. We present tomographic inversion results where the signal-to-noise ratio of the first arrival times is considered as a data quality measure during tomographic inversion. This new data quality weighting scheme is supposed to provide more reliable inversion results. Information about the reliability of the tomogram provided along with the seismic tomogram may support the geophysicist interpretation. The effect of the data quality weighted inversion is studied on a field data set.

Seismic pavement testing

Authors: Nils Ryden
Engineering Geology, Lund University, Sweden
Seismic surface wave testing can provide valuable data for material characterization of pavement layer properties. Measurements can be performed as quality control during or after pavement construction. The thickness and stiffness of the top layer in a pavement construction can be evaluated in a simple manner based on Lamb wave propagation in a free plate. However, due to the complex interaction of higher modes of Lamb type of waves in the embedded layers the evaluation of deeper pavement layers is more challenging. A method for full-wavefield inversion is described and demonstrated on a real pavement construction. Recent developments towards non-contact scanning seismic testing of pavements using microphones is also presented.

Assessment of Dynamic Characteristics of Contemporary Buildings under Earthquake Loading

Authors: Abdelrahman Ashri*, Aman Mwafy
Civil and Environmental Engineering Department, United Arab Emirates University, UAE
This paper aims at evaluating the dynamic characteristics of modern multi-story buildings with different structural systems and diverse configurations under earthquake loading. Ten reference structures of low, medium and high-rise buildings are selected, fully designed and detailed according to the international building codes and construction practice adopted in the UAE and surrounding region. The selected structures vary in height from 2 to 100 stories, with three different lateral force resisting systems, namely flat slab-columns (FSC), shear walls (SW) and tube in tube (TIT) systems. The elastic and elongated dynamic cherectristics are estimated through eigenvalue analysis (EVA) and dynamic time history analysis (THA) using the fast Fourier transformation (FFT) algorithm. It is concluded that the average period elongation at the life safety limit state is 2.2, 1.6 and 1.1 for the FSC, SW and TIT systems, respectively. At the collapse prevention performance level, the period elongation for the above-mentioned systems is 2.8, 2.0 and 1.3, respectively. An effective stiffness of 0.5EI, 0.8EI and 1.0EI is proposed for design based on this study for the vertical members of the FSC, SW and TIT structural systems, respectively.

• High Resolution Seismic Reflection in Geotechnical and Hydrogeological Applications
Authors: Marcellus Gregor Schreilechner*, Christoph Georg Eichkitz
Joanneum Research
Commonly, seismic reflection is used for hydrocarbon detection and monitoring of hydrocarbon reservoirs. The advantage of an active geophysical methodology with an acoustic wave field is that it can be performed according to needed target depths. For geotechnical and hydrogeological projects the targets are mostly in depths from few meters to several hundreds of meters. The vertical and lateral resolution depends strongly on the used frequencies and the velocities of the near surface layers. As high frequencies can be obtained with explosives, we are using for geotechnical applications mostly low charges of explosives or electrical detonators exclusively instead of a sledge hammer. In comparison with classical environmental geophysical methods such as geoelectrics, the application of seismic reflection has one big disadvantage – it needs huge financial and technical efforts. In this abstract we present different examples of seismic reflection for near surface applications. In the first example seismic reflection application for ground water detection is shown using sequence stratigraphic interpretation. The second example is a seismic pre-investigation for the underground railway of Vienna with ultra-shallow unexpected gas deposits and in the third example an ultra-shallow railway tunnel investigation in hard rock environment is presented.

Geophysical and Geotechnical Techniques: Complementary Tools in Studying Subsurface Features
Authors: Haydar Baker*, Amir Gabr
UAE University, P.O.Box 15551, Al-Ain, UAE;
Authors: Mohamed Djeddi
USTHB, Laboratoire de Géophysique, Alger, Algeria
During site characterization for any construction project, certain hesitation and uncertainty attitude from the Geotechnical Engineers always existed towards the role of geophysical surveys; and the question which is always being asked on how the geophysical techniques can help and be useful to the geotechnical studies and to site selection procedures.
In this paper the important role of the geophysical methods is demonstrated through case studies, and how the geotechnical and geophysical techniques should be considered as complementary techniques. The results of geophysical survey can serve as guidelines for placing the geotechnical boreholes and the geotechnical data can be used to ground truth geophysical results.
Examples from the United Arab Emirates and different parts of the world are given. A reference is given to the initiative of Abu Dhabi Emirate to make the geophysical survey mandatory for obtaining the building permit for any type of construction


Geophysical and Geotechnical Techniques: Complementary Tools in Studying Subsurface Features

Authors: Haydar Baker*, Amir Gabr
UAE University, P.O.Box 15551, Al-Ain, UAE;
Authors: Mohamed Djeddi
USTHB, Laboratoire de Géophysique, Alger, Algeria
During site characterization for any construction project, certain hesitation and uncertainty attitude from the Geotechnical Engineers always existed towards the role of geophysical surveys; and the question which is always being asked on how the geophysical techniques can help and be useful to the geotechnical studies and to site selection procedures.
In this paper the important role of the geophysical methods is demonstrated through case studies, and how the geotechnical and geophysical techniques should be considered as complementary techniques. The results of geophysical survey can serve as guidelines for placing the geotechnical boreholes and the geotechnical data can be used to ground truth geophysical results.
Examples from the United Arab Emirates and different parts of the world are given. A reference is given to the initiative of Abu Dhabi Emirate to make the geophysical survey mandatory for obtaining the building permit for any type of construction.



High Resolution Seismic Reflection in Geotechnical and Hydrogeological Applications

Authors: Marcellus Gregor Schreilechner*, Christoph Georg Eichkitz
Joanneum Research
Commonly, seismic reflection is used for hydrocarbon detection and monitoring of hydrocarbon reservoirs. The advantage of an active geophysical methodology with an acoustic wave field is that it can be performed according to needed target depths. For geotechnical and hydrogeological projects the targets are mostly in depths from few meters to several hundreds of meters. The vertical and lateral resolution depends strongly on the used frequencies and the velocities of the near surface layers. As high frequencies can be obtained with explosives, we are using for geotechnical applications mostly low charges of explosives or electrical detonators exclusively instead of a sledge hammer. In comparison with classical environmental geophysical methods such as geoelectrics, the application of seismic reflection has one big disadvantage – it needs huge financial and technical efforts. In this abstract we present different examples of seismic reflection for near surface applications. In the first example seismic reflection application for ground water detection is shown using sequence stratigraphic interpretation. The second example is a seismic pre-investigation for the underground railway of Vienna with ultra-shallow unexpected gas deposits and in the third example an ultra-shallow railway tunnel investigation in hard rock environment is presented.

Assessment of Dynamic Characteristics of Contemporary Buildings under Earthquake Loading

Authors: Abdelrahman Ashri*, Aman Mwafy
Civil and Environmental Engineering Department, United Arab Emirates University, UAE
This paper aims at evaluating the dynamic characteristics of modern multi-story buildings with different structural systems and diverse configurations under earthquake loading. Ten reference structures of low, medium and high-rise buildings are selected, fully designed and detailed according to the international building codes and construction practice adopted in the UAE and surrounding region. The selected structures vary in height from 2 to 100 stories, with three different lateral force resisting systems, namely flat slab-columns (FSC), shear walls (SW) and tube in tube (TIT) systems. The elastic and elongated dynamic cherectristics are estimated through eigenvalue analysis (EVA) and dynamic time history analysis (THA) using the fast Fourier transformation (FFT) algorithm. It is concluded that the average period elongation at the life safety limit state is 2.2, 1.6 and 1.1 for the FSC, SW and TIT systems, respectively. At the collapse prevention performance level, the period elongation for the above-mentioned systems is 2.8, 2.0 and 1.3, respectively. An effective stiffness of 0.5EI, 0.8EI and 1.0EI is proposed for design based on this study for the vertical members of the FSC, SW and TIT structural systems, respectively.

Reliability maps for seismic tomography
Authors: Thomas Fechner*
Geotomographie GmbH, Neuwied, Germany;
Authors: Solomon Ifeanyi Ehosioke
University of Goettingen, Germany;
Authors: Sonja Mackens, Lutz Karl
Geotomographie GmbH, Neuwied, Germany;
Authors: Daryl Tweeton
GeoTom LLC, Apple Valley, Minnesota

Seismic borehole tomography has become a standard method and is routinely used for the detection of karstic phenomena and the delineation of geological structures. Seismic tomography is believed to be the seismic method promising highest accuracy and reliability. Remaining uncertainties due to a non-zero residual travel time fit during data inversion are often neglected. However, data quality has a significant influence on the accuracy of a travel time pick. We present tomographic inversion results where the signal-to-noise ratio of the first arrival times is considered as a data quality measure during tomographic inversion. This new data quality weighting scheme is supposed to provide more reliable inversion results. Information about the reliability of the tomogram provided along with the seismic tomogram may support the geophysicist interpretation. The effect of the data quality weighted inversion is studied on a field data set.

Use of electrical resistivity tomography for mapping the extensions of an existing cavity, a case study from Doha, Qatar

Authors: Mahmoud K. Harb*, Emad Sharif, Tanzeel Ur Rehman

Sabir-Arab Center for Engineering Studies, Dubai, UAE

The presence of natural voids and cavities in subsurface karstic limestones causes severe problem for civil engineering and environmental management. The presence of such features is one of the major concerns for the construction sector in Qatar. These cavities have led to ground subsidence eventually leading to damages to infrastructures such as depression and cracking of the buildings and roads. The main objective of this study was to indicate the extension of large cavity located in Doha. Only one main technique; Electrical Resistivity Tomography (ERT-2D), was proposed/specified and used for subsurface cavity detection. The geophysical survey was calibrated and verified by direct drilling of Fourteen (14) boreholes. Analysis and interpretation of the findings have identified existence of several subsurface open and sediment in-filled cavities. Correlation between ERT results and ground materials was established. Accordingly; risk map was established which identified the likely significance of the encountered risks to the proposed development/construction.

Imaging of Landslide Deposits around Uzungöl Lake (Trabzon-Turkey) by Refraction Tomography and MASW

Authors: G. Vanli Senkaya*, H. Karsli, M. Senkaya, R. Güney

Karadeniz Technical University Geophysical Engineering Trabzon Turkey
Uzungöl Lake and around are located on the landslide deposits which occurred due to an historical landslide. As constructing and commercial, social and cultural development are increasingly rising in the area, seismic risk analyses are need to be accurately done due to the peculiarities of the place where it is located. However, there is not enough geoscience study or no geophysical survey around Uzungöl Lake to reveal sub-surface conditions. Refraction tomography and active surface wave analysis (MASW) were used to image the thickness of land slide deposits, determine P and S-wave velocities of sub-surface. The analyses from 16 profiles demonstrate that the thickness can be seen around 15-20 meters on the west side of the study area, it reaches 30 m and more on the south side. Also, the general appearance of deposit thickness is that it increases towards the lake and maximum thicknesses obviously occur on coastal of the lake.

Evaluating of the Visible Cracks and Related Damage in the Pavement Road (Maria Island Bridge-Abu Dhabi City) Utilizing Seismic Multi Analysis Surface Waves (MASW) and Ground Penetration Radar (GPR)

Authors: Mohammed Hassouneh
Tatweer for Geophysical Studies and Consulting
This paper describes the objectives, the methods used, and the results of the investigation. It also will provide recommendations. The objective as stated in this paper is to evaluate the visible cracks and related damage on the new constructed road in Abu Dhabi city utilizing two geophysical techniques; seismic Multi Analysis Surface Wave (MASW) and Ground Penetration Radar (GPR). MASW technique is a recently developed seismic method that deals with relatively lower frequencies and shallower investigation depth ranges than do conventional high-resolution seismic methods. It provides shear-wave velocity (VS) information of near-surface materials in a highly cost-effectively manner. Because of the relatively significant value of this (VS) information in most geotechnical engineering projects and also because of the relatively simple in-field operation and data processing, it is gaining popularity among engineering communities.
Ground Penetrating Radar (GPR) is a nondestructive ground survey method that can be used in assessing roads, railways, bridges, airports, tunnels and environmental objects. Its main advantage is the continuous profile it provides of the road structure and subgrade soil. The GPR technique is becoming an increasingly important tool especially for structural evaluation of roads in the design phase but recently it has also been used more frequently in quality control and quality assurance of paving and construction projects.
Analysis and interpretation of the findings from MASW and GPR scanning surveys has confirmed that there are loose materials existing at a depth between 2.5 and 4 m under the cracked road. This very week layer of loose unconsolidated materials influenced by the strong vibrations from the vicinity new tower construction. The vibrations generated seismic waves (ground shaking) that caused rapid compaction, rearrangement of soil particles and settling of subsurface materials (particularly in the layer of loose, non-compacted, and variable sandy sediments). The visible and invisible cracks on the road have been developed due to the amplification of the ground shaking effects by the unconsolidated materials under the asphalt pavement road.

Keynote Speech: Technology and Geoforensics

Authors: Alastair Ruffell
School of Geography, Archaeology & Palaeoecology, Queen’s University, Belfast, N.Ireland, BT7 1NN
From the landscape-scale of searching for buried objects using Global Navigation Satellite Systems, through the challenge of finding sunken objects in water, to the non-destructive analysis of trace evidence, technology is fundamental to recent advances in Geoforensics (the use of Earth Science techniques in legal enquiries). At the macro-scale, wearable devices that allow both the remote direction of personnel, as well as recording their location and tracks, can be used to plan, carry out and review searches in featureless areas (moorland, forest, deserts). At the medium (tens of metres) scale, the search and inspection of water bodies is a major challenge for both serious crime as well as engineering and archaeology. Combined side-scan/forward-facing sonar and boat-operated ground penetrating radar (more correctly, water penetrating radar) has proven very effective in the search for victims of drowning, suicide and homicide, as well as bridge and quay/jetty inspection: both use the same technology. When recovered (sometimes using the above technology), trace (less than 2g of material) geological evidence is often critical in establishing a case, in the absence of DNA, blood, fibres or fingerprints. A major issue is what to do with such samples? Incorrectly deployed destructive analysis will preclude other investigations. A suite of new devices, from digital colormeters, Fourier Transform Infrared Spectroscopy, Portable XRF and the in situ analysis by x-ray diffraction are now available to the forensic investigator, to better inform what the trace sample is, and thus the most appropriate method of further, probably destructive, analysis.

Recent advances in high-frequency surface-wave methods
Authors: Jianghai Xia
Subsurface Imaging and Sensing Laboratory, Institute of Geophysics and Geomatics, The China University of Geosciences, Wuhan, China, and Hubei Subsurface Multi-scale Imaging Key Laboratory, Institute of Geophysics and Geomatics, The China University of Geosciences, Wuhan, China;
Authors: Lingli Gao, Yudi Pan, Chao Shen
Subsurface Imaging and Sensing Laboratory, Institute of Geophysics and Geomatics, The China University of Geosciences, Wuhan, China
Multi-channel Analysis of Surface Waves (MASW) analyzes high-frequency Rayleigh waves to determine near-surface shear (S)-wave velocities. The method is getting increasingly attention in the near-surface geophysics and geotechnique community in the past 20 years because of its non-invasive, non-destructive, efficient, and low-cost advantages. They are viewed by near-surface geophysics community as one of most promise techniques in the future. However, they face unique problems related to extremely irregular velocity variations in near-surface geology or man-made constructions, for example, highway, foundation, dam, levee, jetty, etc., which are not solvable by techniques or algorithms widely used in earthquake seismology or oil/gas seismic exploration.
Calculation of dispersion curves by existing algorithms may fail for some special velocity models due to velocity inverse (a high-velocity layer on the top of a low-velocity layer). Two velocity models are most common in near-surface applications. One is a low-velocity half space model and the other a high-velocity surface layer. The former model results in a complex matrix that no roots can be found in the real number domain, which implies that no phase velocities can be calculated in certain frequency ranges based on current existing algorithms. A solution is to use the real part of the root of the complex number. It is well-known that phase velocities approach about 91% of the S-wave velocity of the surface layer when wavelengths are much shorter than the thickness of the surface layer. The later model, however, results in that phase velocities in a high-frequency range, calculated using the current algorithms, approach a velocity associated with the S-wave velocity of the low-velocity layer NOT the surface layer. These results conflict with the feature of surface waves and results in an incorrect inversion model. We proposed a direct and essential solution to correctly calculate surface-wave phase velocities due to this model. The algorithm that we newly developed can handle any arbitrary velocity models, which is the foundation of high-frequency Rayleigh-wave methods and is critical to near-surface applications.
Non-geometric wave exists uniquely in near-surface materials, especially in unconsolidated sediments. It occurs in near-offsets in high-frequency Rayleigh data. It is valuable for a quick and accurate estimation of S-wave velocity of the surface layer. Our study shows that non-geometric waves are leaky waves and dispersive. Leaky surface wave could cause misidentification when treating the leaky-wave energy as fundamental or higher modes. Such misidentification will result in wrong inversion results.
Multichannel Analysis of Love Waves (MALW) analyzes high-frequency Love waves to estimate near-surface S-wave velocities. Based on 2D geometry spread in which source and receivers are placed along a same line, current MALW fails to work in three-dimensional (3D) seismic acquisition system. This is because Love-wave particle-motion direction is perpendicular to its propagating direction, which makes it difficult to record Love-wave signal in 3D geometries. We proposed to perform 3D MALW via recording two orthogonal horizontal components (in-line and off-line components) at each receiver point at the same time, and then rotating and composing those two components to recover Love-wave data. A synthetic model and two real-world examples verified the validity as well as the high effectiveness of our proposed method.

Geophysical Data Fusions for Resolution Improvement

Authors: Gang Tian, Shahid Ali Shaikh, Abdullah Lizan, Ran Chen, Yiming Wang
Department of Earth Science, Zhejiang University, China
Nowadays, data fusion is quite a modern word for information technology. Actually, there has been a steady increase for decades in the application of geophysical data fusion to improve resolution. We carried out the data fusion study mainly from geophysical sensors’ stage.
At first, in order to solve the coupling problems occurred in different surface conditions, the special coupling geophone system for a certain condition is designed to match ordinary geophone data by site observation comparison. Then the coupling filter was applied to the ordinary geophones which were used at all surface cases. After that, the filtered data were treated as original acquired data. That means that the coupling problem can be solved by designing few special coupling geophone systems and filtering the data obtained by ordinary geophones. The example was given in a desert area.
Secondly, it is known that there are some geophones with different frequency responses for choose in field survey which is a dilemma for geophysicists. We considered combining the frequency advantages of different kinds of geophones to broaden the effective bandwidth of the acquired data by using a partial frequency match filtering method in data processing which helps to improve the resolution of seismic reflected. We collected data using two kinds of geophones, normal geophones with natural frequencies of 60Hz and 100Hz and towable cable geophones which can receive signal frequency up to several hundred Hz. We applied a partial frequency match filtering method, which has improved the bandwidth frequency by focusing the data from above geophones in data processing, and achieved results showing the existence of the target layer. The example was given in an archaeological geophysical investigation case.
Thirdly, we know that the penetration depth and resolution of energy of Ground Penetrating Radar (GPR) is purely relying upon the central frequency of a particular antenna. When the central frequency of transmitting and receiving antennas is not the same then the swap effect is different. We found that the impact of transmission antenna frequency is greater on the data. The major impact of receiving antenna frequency is on the resolution. Therefore it can be possible that the penetrating depth and the resolution with the optimum combination configure of antennas could be improved than the one with normal configurations of antennas as well as by applying a match filter afterwards. We will show an example in a test site for archaeological purpose.
And lastly, the data from Electrical Resistivity Tomography (ERT) methods were studied in observation point of view. It is know that the inversion data from different array types have different features, which could create various geo-electric image results and bring some difficulties to interpretation. The simulation and observation of 2-D ERT integrated data of Wenner and Schlumberger arrays in a test site were studied, since these two configurations have different characteristics for the sensitivity of resistivity variation. The observation of 3-D ERT from the site integrated data of pole-dipole and dipole-dipole arrays were also tested, because the inversion data have different depth values. The simulation and experimental results show that the integrated data method discussed here improves the precision of resistivity imaging.

Comparison Tests for Surface Electromagnetic Prospecting System(SEP)

Authors: Qingyun Di*, Zhongxing Wang, Changmin Fu, Zhiguo An
Key Laboratory of Shell Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029
In recent years, induced electromagnetic methods applied in deep ore body prospecting, such as CSAMT and MT method have undergone rapid and great development. However, land EM exploration instruments were almost monopolized by several big companies from U.S., Canada and Germany. To develop Chinese own equipment and technology, we undertook the Sinoprobe project to research surface electromagnetic prospecting(SEP) system in 2010, andsome achievements have been obtained.SEP system is a land electromagnetic instrument developed by our research group; including high-temperature superconductor magnetic sensor(HTSC), fluxgate sensor, induced magnetic sensor and receiver box, which could be used for CSAMT, AMT and MT data acquisition.
In2012, a number of integration tests were carried out at Hebei, Liaoning, Gansu, et al. Based on the problems exposed during these tests, SEP research group conducted thorough analysis, and made some optimization and improvements on this system. In 2013, a test of overall ability of SEP system was conducted at Caosiyao molybdenum mine in Xinghe, Inner Mongolia, China in order to test the performance and reliability of SEP system in practical exploration. Caosiyao molybdenum mine is a super-large-scalemolybdenum mine. Even though detailed geological survey has been done in this area and geological structuresand mineral distribution revealed by boreholes are quite clear, minerals in this area are yet to be exploited. Hence, there is little interference, which is beneficial for data acquisition and instrument comparison in the field.
Using different schemes, several contrast tests were performed. Firstly, we compared the HTSC with commercial induced magnetic sensor using the same station. The comparison result showed that in the presence of interference, HTSC was inferior to the latter in high and low frequency band, while the performance of both sensors in quiet environment was consistent. Hence, there is still opportunity for improvement on the HTSC sensor. Secondly, using the same sounding point, we also compared fluxgate sensor with commercial induced magnetic sensor via different frequency range. The result showed fluxgate sensor was more suitable for low-frequency MT survey. Thirdly, we did transmitter comparison, and the result indicated that SEP transmitter performed better than GGT-30 and TXU-30 in the frequency band lower than 700Hz. Fourthly, we compared the observation data from SEP system with those fromV8 and GDP32 system at the same transmitting location and profile. The obtained sounding curves and inversion results were consistent. Finally, we compared SEP with V8 system in MT test, and got consistent result. The study showed that the SEP system can be used for a long-time MT observation, and its performance was comparable with V8 system. In conclusion, the comprehensive test showed that the self-developed SEP system’s quality has reached or exceeded that of similar foreign commercial products, and it is competent for practical exploration.

Applications of 3-D modeling & inversion technology in AMT exploration with varied topography

Authors: Ruan Shuai*
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China, and State Key Laboratory of Earthquake Dynamics, Institute of geology, China Earthquake Administration, Beijing, 100029, China;
Authors: Wang Xuben, Zhou Jun
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China;
Authors: Tang Ji
State Key Laboratory of Earthquake Dynamics, Institute of geology, China Earthquake Administration, Beijing, 100029, China
In a Kimberly exploration project, which is very hard to locate the real target, with prior information from 1-D inversion of typical sites, we build a 3-D background model to calculate AMT response influenced by topography and non-homogeneous near-surface, then use model response to correct measured data’s impedance phase invariant. The corrected phase invariant terms to be a powerful tool to rule out misrepresentative abnormality on traditional 1-D and 2-D inversion. All these qualitative analysis give use better understanding of real resistivity distribution so that both the lower & upper bound even initial model of 3D AMT inversion can be sketchily determined. Finally, bound constrained 3-D inversion results lead to a more reliable resistivity model for geological interpretation.

The Application of Non-Seismic Data in Near Surface Velocity Modeling in Surface Volcanics Area

Authors: Yang Zhanjun*
BGP Inc., China National Petroleum Corporation
Authors: Feng Wenyan, Lei Dong
China Southern Petroleum Exploration and Development Corporation
Authors: Jiang Wenbo
BGP Inc., China National Petroleum Corporation
Near surface structure is extremely complex in surface volcanic rock areas. Uphole survey is a well used method to investigate surface volcanics since its high vertical resolution. Due to its higher costs and lower productivity, uphole survey is not performed with an enough density, which makes near surface velocity model unsatisfied, and leads to poor effects of seismic excitation and static correction. This paper presents an economic and effective solution, which take uphole survey and non-seismic survey to perform near surface structure investigation, and further establish near surface velocity model. A case in this paper shows the improvement of near surface velocity model and seismic static correction effect


GPR Signals Analysis of Post-tensioned Prestressed Concrete Girder Defects
Authors: Sixin Liu*, Lei Fu
College of Geo-exploration Sci. & Tec., Jilin University, China
Accurate inspection of duct condition in the post-tensioned prestressed concrete (PPC) is an essential part for GPR concrete inspection. The purpose is to inspect the grouting condition of the ducts where the strands are located, to find if there is void in the ducts, and if there exists water. In order to investigate the radar image characteristics of different PPC duct defects, a number of model girders were manufactured. Three major ducts are included in our study: 1) well grouted and no void (normal condition); 2) duct is half filled, and the void is filled by water or air; and 3) duct is not filled at all, and the duct is water or air filled. The data corresponding to seven different situations are acquired and processed. It is found that radar can detect the first interface in the duct, and the detailed structure inside the duct cannot be “seen” from the images directly. Characteristic curves help the interpretation very much. Complete void duct is the easiest to be differentiated from others. The signature for this situation is characterized with strong and clear reflection interface which becomes weaker as the void is water-filled. Normal condition shows weakest reflection interface. As for half void situation, front scan shows similar result to normal condition whether it is water or air filled, and back scan shows similar features to completely void situation. The experiment and analysis is helpful and instructive for practical engineering inspection


CannyTEM – a high-resolution transient electromagnetic system based on mobile technology and artificial intelligence

Authors: Xing He, Rujun Chen*
Central South University, Changsha, P.R.China;
Authors: Hongchun Yao, Hong Wu, Jieting Qiu, Ruijie Shen, Qiang Ren, Honghua Shi, Hai Dong, Shenglong Tan
Champion Geophysical Technology, Changsha, P.R.China
CannyTEM is a ground based high-resolution transient electromagnetic system, which is based on mobile technology and artificial intelligence for easy operation and good quality data acquisition. This paper presents the design, realization, and testing of CannyTEM. CannyTEM is composed of a transmitter, a receiver, two induction coils, and a smart phone or PDA. The transmitter is synced with GPS or cable from the receiver. Its turn-off time is 2.5 μs for 3 A injected current and 40 m × 40 m loop. The receiver owns low-noise amplifier, 24-bit ADC, CPLD, DSP, GPS and embedded computer. The bandwidth of high frequency coil with physical area as 6 m2 is 1.2 MHz. The bandwidth of low frequency coil with physical area as 100 m2 is 50 KHz. A smart phone or PDA offers friendly human-machine-interference for the operation of CannyTEM. A smart phone can control the receiver by WIFI and cabled network. The transmitter can send current waveform to the receiver by RS485. The receiver can acquire TEM data intelligently. The turn-off time, gain of each channel inside the receiver is computed and controlled intelligently. At last, we carried a test with PROTEM47HP. The testing result showed that our design is successful.

Application of 2D Microtremor Survey Method to Detect and Map Beijing Tugou-Gaoliying Ground Fissure
Authors: Peifen Xu*
Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences;
Authors: Suqun Ling
Geo-Analysis Institute Co. Ltd (Japan)
Ground fissure in addition to small faults in the plain areas of Beijing, and even Northern China, form the most common and destructive geological hazards. They have become key risky geological factors to the urban construction and development. Even though it may be avoidable to build major structures above the ground fissure, there is little choice to construct high-speed railways, subways, and underground pipelines without penetrating these hazardous geological features. It is, therefore, critically important to identify and map exact locations of the ground fissure and their spatial distributions. The map will provide valuable information for structural designing or planning to avoid these geological hazards as much as possible to ensure safe construction and operations of these major structures.


Integrated Geophysical Survey to Investigate a Construction Site in Makkah City, KSA
Authors: Fathy Bahloul*, Dirk Orlowsky
DMT GmbH & Co.KG.
Geophysical survey methods used in combination with borehole data for verification provide the most integrated solution for the identification of subsurface conditions. An integrated geophysical survey using CMP-refraction seismic, seismic refraction tomography, electrical resistivity tomography and borehole logging was conducted at a construction site in Makkah, Saudi Arabia. The survey was performed mainly to determine the thickness of the saturated zone, the depth of the groundwater and the depth of the bedrock as well as to delineate near-surface faults and weak zones.
All geophysical results (seismic tomography, resistivity and borehole logs) are combined and jointly interpreted together with the boreholes data in order to calibrate the final interpretation and to generate an integrated underground model.
The chosen interpretation system ensures the generation of exact and consistent spatial images of the subsurface and underground conditions.

Innovative use of Engineering Geophysical for Site Investigations

Authors: Sanjay Rana
PARSAN Overseas Pvt. Limited, New Delhi, India
Engineering geophysics is an efficient means of subsurface investigations. The areas of application of engineering geophysics are only limited by the imagination of practicing professionals. The key to success is right choice of method and integration of various geophysical techniques to remove ambiguity to the extent possible. There are certain site conditions routinely considered as adverse to application of geophysical methods. It has, however, been noticed that little innovation in field data acquisition methodology and integration of techniques can overcome most of these challenges and provide valuable information in these ‘unfavorable‘ site conditions as well.

The objective of paper is to demonstrate efficacy of various techniques with little
Geothermal resource exploration in the region of Hmeïma (Central -Western Tunisia) using resistivity sounding and gravity data
Authors: Farhat Ben Mbarek, Wajdi Belkhiria*, Mohamed Dhaoui
Office National des Mines, ONM, Tunisia
The Hmeima geothermal province, encompassing the structres of Boujabeur, Hmaima, Slata, Harraba and Guarn Halfaya, expresses promising geothermal anomalies in a number of wells. In this area, the potential geothermal aquifer is the Aptian reefal limestone.
The identification and exploitation of these geothermal resources require knowledge of the geometry of aquifers, their hydrodynamics and risks of contamination by Triassic salt deposits.
To attend this aims, a vertical electrical sounding (VES) survey containing 65 VES (AB/2= 1500 m) has been carried out to understand and evaluate the geothermal Aptian aquifer.
The interpretation of VES calibrated to the borehole data helped to image the geometry of the reefal Aptian aquifer. From a geological point of view, under the Mio-Plio Quaternary deposits, the borehole pass throw Albo-Aptian and Triassic strata. An isobath map at the top of Aptian interval shows a depth up to 1200m. This limestone is affected by a fault network with main faults oriented N70, N150 and N130 detected by gravity data analysis and in geoelectrical profiles. In particular, the major faults give a vertical drainage of the thermal reservoir in this area.
On the other hand, this study gave a detailed subsurface mapping of evaporates intrusions that can be a source of contamination of the reservoirs.


Geophysical application in preselecting a high-level radioactive waste site

Authors: Zhiguo An, Qingyun Di*, Ruo Wang, Changmin Fu
Key Lab of Shale gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, PO. Box 9825, No. 19, Beituchengxilu Road, Chaoyang District, Beijing, 100029
This paper discussed comprehensively, the geophysical application in preselecting the high level radioactive waste (HLRW) site in northwest(NW) China. We analyzed 3D large-scale aeromagnetic and gravity results to interpret regional structures which controlled granite rock distribution, and evaluated the integrity of granite rock. Also, we conducted Controlled Source Audio-frequency Magnetotelluric method (CSAMT) survey at a potential site, which may be suitable for underground geological repository. The survey objective was to map out the fractured and crushed zones that resulted from geological structures like active fault, which would cause serious damage to the safety and stability of underground repository. The comparison between the interpreted results and geological information shows that both are in good agreement. The study proves that comprehensive geophysical exploration is helpful in detecting geological structures and evaluating the rock quality.It can also provide the reliable geophysical evidence for further study.

The Integrated Application of Natural Radon-Radioactivity and Electrical Resistivity Tomography to Investigate Karst Cave System: A Case Study from Al-Dahr Cave, N-Jordan

Authors: R. Jaradat*
Yarmouk University, and Gulf Laboratory for Site Investigation and Material Testing
Authors: E. Na’amneh, B. Al-Bataina
Yarmouk University
In this study, radon-radioactivity and electrical resistivity tomography (ERT) methods were used to investigate an existing karst cave system of northern Jordan.
Initial field reconnaissance and testing led to the selection of appropriate field parameters for the used methods. Various electrode configurations were tested (i.e. Wenner, Schlumberger and Dipole-Dipole). Correlating the ERT results with radon profiles showed that the Dipole-Dipole array has the highest resolution limits and that two meters of spacing was enough to maintain the required level of accuracy. Nine profiles; radon of 2-meter intervals and 0.5-meter depths were collected. The location of each profile was subsequently subjected to ERT surveying using the Dipole-Dipole array with 2-meter inter electrode spacing.
The average value of Radon concentrations across all detectors was equal to 6.18kBq/m3 which is higher than that reported as background values from Jordan. The maximum radon concentration equals to 25.17kBq/m3 was collected across the main hall limits of the cave structure. However, the radon concentrations tend to increase across known fault and fracture zone trends. Additionally, elevated concentrations were encountered across the center of the main hall. Some of the fault structure showed possible sealing characteristics, thus hindering the passage of radon gas through specific trend or across thin cave roofs. Several collapse features were seen across the resistivity sections of the subsurface. These localities provide good seepage pathways for the radon gas into the ground surface. Additionally, ERT results showed potential isolated cave extensions that can add to the value of the site.
The results of this study indicated the successful integrated interpretation of radon natural radioactivity and electrical resistivity tomography (ERT) in characterizing karst terrain structures

Geophysical investigation of groundwater resources integrating seismic refraction tomography and resistivity data in Ibadan West, Nigeria

Authors: Olusegun K. Abass*
Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, PR China;
Authors: Musa Bello
Department of Geosciences, University of Lagos, Akoka, Lagos, Nigeria
Secondary porosity formed within hard rock formations as a result of weathering, jointing, faulting or fracturing constitutes areas of special interest in groundwater prospecting. In this study, integrated electrical resistivity and seismic refraction surveys were carried out within the subsurface strata of Ibadan West, Nigeria, to delineate the groundwater potential and aquifer characteristics of the area. The integrated interpreted results revealed four layers overlying the resistive basement: the topsoil, dry sand, saturated sand and the weathered basement. The investigation also revealed the presence of a potential aquifer in the area, with resistivity values of 95 – 295 Ωm, and velocities range of 1650 – 2800 m/s while the depth of the aquifer ranged between 2.8 and 10.4 m. The forth lithological unit which has velocities ranging from 2500 – 3500 m/s and a resistivity value of 1124 – 1946 Ωm is considered the weathered basement. Comparing lithological logs from drilled boreholes with acquired geophysical data, the study area is considered suitable for groundwater development via shallow borehole construction.


Integrated geotechnical and engineering geophysical approach to control groundwater influx: a case study from Abu Dhabi, UAE

Authors: Rasheed Jaradat*, Younes Al-Omari
Gulf Laboratory for Site Investigation & Material Testing, Abu Dhabi, UAE;
Authors: Anmar Abdulaziz
Spectra Geotechnologies and Foundations Contracting, Abu Dhabi, UAE
Shallow groundwater conditions force construction projects and contractors to conduct dewatering and/or water control procedures that tend to affect the competency of foundation material and design of structures. Uncontrolled groundwater may result in a condition causing piping, heaving, reduced stability of excavated slopes and pits, or reduced foundation ability to support loadings and structures (DOD, 2004). Conditions of shallow groundwater are of prime concerns to engineering projects, especially when excavations are carried out within earth materials characterized by elevated hydraulic conductivities.
An integrated geotechnical and geophysical approach was adopted to effectively control ground water influx. Shallow groundwater and poor rock characteristics have led to sever flooding of construction excavation. Multichannel Analysis of Surface Waves (MASW) identified continuous zones of weakness bordering excavation from the southern and western borders of the pit. Interpretation indicated that flooding is taking place below the sheet piles, where drilling of five boreholes around the tank area revealed severe loss of drilling water. The recovered samples showed highly weathered and fractured rock conditions. The loss of drilling water was observed in two boreholes, BH-1 and BH-2, with two levels (referenced to the existing ground level) of water loss; at 5.6m to 15.0m and 13.5m to 18.5m respectively. An engineering solution was proposed aiming at isolating excavation by developing a grout curtain in order to successfully control groundwater influx. A grouting proposal was carefully designed and is under execution.








A Collaborative Methodology for Ground Searches by a Forensic Geologist and Law Enforcement (Police) Officer: Detecting Evidence Related to Homicide, Terrorism and Organized Crime

Authors: Laurance Donnelly*
International Union of Geological Sciences (IUGS), Initiative on Forensic Geology (IFG);
Authors: Mark Harrison
Australian Federal Police, IUGS-IFG & University of Canberra, Australia
In the United Kingdom (UK), law enforcement (police) ground searches for burials for targets such as graves, firearms, drugs, items of value and evidence, have traditionally relied on a counter-terrorism search strategy. This developed in the aftermath of the failed attempts by the Provisional IRA to assassinate the former British Prime Minister, Margaret Thatcher in 1984.
In 1994, a geological search began for a missing person that was believed by the police to be buried in a shallow, unmarked grave, located in a remote upland range of hills in northern England. This search applied techniques and methods conventionally used in mineral exploration and engineering geology ground investigations. This included for example; analysis of air photos and satellite imagery, geological mapping and geomorphological observations, diggability assessments, the production of a Conceptual Geological Model (CGM), phased and systematic geophysical surveys and soil probing. The CGM enabled to most suitable suite of geophysical methods and associated search assets to be chosen, which were appropriate for the prevailing geological conditions and grave being sought.
In the early 2000s, this geological based search evolved to incorporate more conventional law enforcement, mainly counter-terrorism based search methods. The result, over the decade which followed, was the emergence of a new ground search strategy that combined both the geological and law enforcement approaches.
This new and innovative search strategy has raised awareness within law enforcement communities of the value in understanding the geology and ground conditions before the choice and deployment of geophysical instruments and other search assets. This collaborative methodology is based on the division of a search into three principal phases (or stages); known as Pre-search, Search and Post-Search. Each of these comprises series of sub-sub stages. This strategy enables the searcher to develop a methodology that best suits the prevailing geology and in context with the nature of the targets being sought. This method offers a high assurance, cost-effective, proportionate and pragmatic search to be deployed to negate or locate the presence of suspected target buried at a shallow depth in the ground. This strategy is now increasingly being used in the UK and internationally for open area searches for burials.


Soil in Search and Evidence in the Case of Missing Person Pamela Jackson

Authors: Lorna Dawson
The James Hutton Institute, Aberdeen;
Authors: Aelf Sampson
Durham Constabulary, Durham Constabulary, Aykley Heads, Durham;
Authors: Adam McConochie, Karl Harrison, Gaille Mackinnon
Alecto Forensic Services Ltd, Preston;
Authors: Ian Jefferies
South Yorkshire Police, College Road, Doncaster, South Yorks;
Authors: Laurance Donnelly
Worley Parsons, Moorfield Court,11a Alma Road, Headingley Leeds
Soil can be a very useful technique in both determining provenance in a law enforcement/police search and also as physical evidence to determine if an offender or item was associated with a crime or location (Dawson and Hillier, 2010). This paper illustrates an example where soil information assisted in the search for a grave and also provided evidence that was presented in court. Operation Sorrento is also a good example of where there was effective team work, and illustrates interdisciplinary integration, which included police investigators, police search teams, a forensic geology ground search specialist, forensic service providers and forensic soil scientists, all with particular complementary expertise. Operation Sorrento was a large scale, high profile ‘No-body Murder’ investigation which lasted over several months, in the winter of 2013, stretching from County Durham to West Yorkshire, in England, UK.
Permalink: http://dx.doi.org/10.1190/iceg2015-027

Site investigations using resistivity tomography: case studies from civil engineering and archeological examples

Authors: Farhat Ben M’Barek, Wajdi Belkhiria*, Mohamed Dhaoui, Wissem Marzouki
Office National des Mines (ONM), Tunisia
The use of geophysical methods aims to determine the characteristics of the different rocks in order to understand their shape and their lithology. The fields of application of these methods are very extensive. This implies that the method we will choose for any study should be properly adapted to the problem. The team of Geophysics of the National Office of Mines carried out several studies in the areas of civil engineering and archeology using the electrical method.


Improving Target Identification and Characterization From GPR Data Using Isosurface Renders Technique

Authors: Mahmoud Gaballah*
National Research Institute of Astronomy and Geophysics (NRIAG); 11421 Helwan, Cairo, Egypt, and currently with College of Science and Humanities in Hawtet Sudair, Majmaah University, K.S.A.;
Authors: Deen Goodman
Geophysical Archaeometry Laboratory Inc., 20014 Gypsy, Woodland Hills, California, U.S.A.;
Authors: Magdy Atya, Hany Salah
National Research Institute of Astronomy and Geophysics (NRIAG); 11421 Helwan, Cairo, Egypt
Ground–penetrating radar (GPR) is a high efficient and high–resolution geophysical technique used to investigate archaeological and engineering sites in a nondestructive manner. To effectively analyze GPR data sets, their combination with modern visualization techniques (e.g., isosurface rendering) has been acknowledged to facilitate interpretation beyond classical time slice analysis. We introduce two case study, in which we focus on the application of isosurface rendering to emphasize temporal and spatial variations within GPR archaeological data cubes and engineering problems. First case study main goal was to localize and potentially characterize cut-off tombs inside ferrous sandstone situated at Al-Nadura Temple, Al-Kharga City, New Valley. In the second case study we used GPR technique to evaluate the potentiality of this near surface geophysical method to image out the fracture system in a limestone plateau at Al-Mokattam site, Cairo, Egypt. The two case study GPR data were acquired with GSSI SIR 2000 system using 400 MHz shielded antenna and inline spacing 0.5m in both x and y direction. By comparing the visualized isosurface data to the conventionally processed time-slice, we demonstrate the superior interpretability of the isosurface technique for target identification and characterization. Based on these two case study, we illustrate the potential of such isosurface technique analyses towards a more comprehensive GPR data interpretation and target identification.
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