Applications of hydrogeophysics in characterization of subsurface architecture and contaminant plumes

Geophysical methods have been applied to a wide range of hydrogeological problems. With improvement in geophysical inversion algorithms and measurement tools, significant achievements have been made in the characterization of subsurface architecture, time-lapse monitoring of hydrogeological process and contaminant plumes delineation. In this paper, we summarize the geophysical methods that are most widely used in hydrogeology including Electrical Resistivity Tomography(ERT), Induced Polarization(IP), Ground Penetrating Radar(GPR) and Electromagnetic Induction(EMI). Three examples including lab and field works are used to demonstrate current application of geophysical methods for characterizing subsurface architecture and contaminant plumes. Though great progress has been made in hydrogeohysics over the last few decades at home and abroad, challenges still remain in practical applications. More recently, hydrogeophysics continues to develop in the areas of establishment of hydrogeophysical models, large-scale architecture characterization, uncertainty analysis, biogeochemical process monitoring and ecosystem science.

Evidence supporting New Geophysics

In the last decade a New Geophysics has been proposed,whereby the crust and uppermost ~400 km of the mantle of the Earth are so pervaded by closely-spaced stress-aligned microcracks(intergranular films of hydrated melt in the mantle) that in situ rocks verge on failure by fracturing,and hence are critical-systems that impose a range of fundamentally-new properties on conventional sub-critical geophysics.Enough of these new properties have been observed to confirm that New Geophysics is a new understanding of fluid/rock deformation with important implications and applications.Evidence supporting New Geophysics has been published in a wide variety of publications.Here,for clarification,we summarise in one document the evidence supporting New Geophysics.

Four Color Theorem and Applied Geophysics

A selection of a number of geophysical methods to solve different geological, geodynamical, environmental, archaeological and other problems usually has no theoretical substantiation. The solution to this “four color” mathematical problem is able to assume that two independent geophysical methods are sufficient theoretically to characterize the geological-geophysical peculiarities of the area under study.

Geophysics Contribution for the Determination of Aquifers with a Case Study

The determination and monitoring of aquifer formations on the eastern border of Moroccan Gharb basin are very difficult because of their spatial and temporal variation. To delimit these formations, a geophysical survey of 52 geoelectric soundings was performed with a mesh of 500 m and electrodes distance between 1000 m and 3000 m. Geoelectric sections and resistivity maps show a horst and graben structure. The correlation of existing oil drillings shows that the Jurassic and Neogene formations are both affected by normal faults causing Jurassic deposits collapse with local thickening of the Miocene deposits, and reverse faults delimiting tectonic slices due to tension caused by prerifaine nappe advance. This fact confirms the generated structure by the resistivity method. The isobath map of resistant formations's roof show average depths extending from 400 to 800 m for calcareous sandstone that are potential aquifers while oil drillings indicate over 1000 m depths.

International Union of Geodesy and Geophysics: 27th General Assembly Conference

"Beyond 100: The next century in Earth and Space Science"The 27th IUGG General Assembly will be held July 8-18,2019 at the Palais des Congrès in Montréal,Québec,Canada.This is a special opportunity for participants from Canada and from around the world to come together and share their science and culture.2019 marks the 100th anniversary of IUGG;we will look back on the accomplishments of the previous century of Earth and space science research,and forward to the next century of scientific advancement.Join us for a host of scientific activities,including special public lectures,keynote Union lectures and a wide variety of themed sessions.

Mechanical Modeling of Dike Propagation: Methods, Recent Results and Links to Geophysics

Magma is transported in brittle rock by diking.Diking plays a key role in tectonic phenomena such as continental rifting and plate divergence at mid-ocean ridges.In spite of the importance of understanding how magma

A review of the New Geophysics:a new understanding of pre-fracturing deformation in the crack-critical crust with implications for hydrocarbon production

这篇论文考察是常规液体岩石变丑的基本修订的切开的砍波浪(seismic-birefringence ) 的新理解。它是有为几乎所有稳固地球的地球科学的含意的一个新地球物理，包括烃探索和生产，并且地震预报。切开的砍波浪的普遍观察显示出那变丑在在 situ，岩石被排列压力的浸透液体的谷物边界裂缝控制并且优先地在地球外壳中面向了毛孔和在几乎所有火、变形、沉积的岩石中弥漫的毛孔喉咙。这些浸透液体的 microcracks 是岩石团和控制岩石变丑的最顺从的元素。切开在几乎所有的 microcracks 摇的表演的度是那么仔细他们由断裂接近 fracture-criticality 和失败的 spaced，并且是有所有批评系统的蝴蝶翅膀敏感的批评系统。由于这 crack-criticality，在改变条件下面的浸透液体的排列压力的 microcracked 岩石的进化能与各向异性的 poroelasticity (无尾猿) 被建模。因而，低级变丑能是：监视了，砍波浪切开；带着无尾猿计算的未来行为；未来行为带着无尾猿预言了，如果处于条件的变化能被确定；并且原则上，未来行为由反馈控制了。这份报纸考察我们低级预先断裂的变丑的新地球物理的当前的理解。

Determination of rock mass integrity coefficient using a non-invasive geophysical approach

Determination of rock mechanical parameters is the most important step in rock mass quality evaluation and has significant impacts on geotechnical engineering practice.Rock mass integrity coefficient(KV)is one of the most efficient parameters,which is conventionally determined from boreholes.Such approaches,however,are time-consuming and expensive,offer low data coverage of point measurements,require heavy equipment,and are hardly conducted in steep topographic sites.Hence,borehole approaches cannot assess the subsurface thoroughly for rock mass quality evaluation.Alternatively,use of geophysical methods is non-invasive,rapid and economical.The proposed geophysical approach makes useful empirical correlation between geophysical and geotechnical parameters.We evaluated the rock mass quality via integration between KV measured from the limited boreholes and inverted resistivity obtained from electrical resistivity tomography(ERT).The borehole-ERT correlation provided KV along various geophysical profiles for more detailed 2D/3D(two-/three-dimensional)mapping of rock mass quality.The subsurface was thoroughly evaluated for rock masses with different engineering qualities,including highly weathered rock,semi-weathered rock,and fresh rock.Furthermore,ERT was integrated with induced polarization(IP)to resolve the uncertainty caused by water/clay content.Our results show that the proposed method,compared with the conventional approaches,can reduce the ambiguities caused by inadequate data,and give more accurate insights into the subsurface for rock mass quality evaluation.

第三届全国应用地球物理研讨会和《Applied Geophysics》杂志编委会在中国石油大学(北京)召开

9月16日至17日，第三届全国应用地球物理学术研讨会在中国石油大学（北京）举行，来自全国15家单位的专家、老师和学生共80余人参加了本次研讨会。本次研讨会的主题为“油气地球物理探测”。会议由中国石油大学（北京）地球物理与信息工程学院肖立志院长主持，中国石油大学（北京）陈大恩副校长致欢迎词。本次一天半的研讨会共交流30篇学术报告，内容丰富，反映了本学科的最新进展，促进了应用地球物理学科交流与发展。

Comprehensive analysis of safe mining to heavy and steep coal seam under complex geophysics environment

In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed frequently during mining.Firstly,mining condi- tions,spatial structure and parameters were investigated.Then physical simulation and dynamic numerical tracing and elaborate simulation relating roof and top-coal were ap- plied based on 2D-Block Program and quantitative regularity of stress at variable depths had been estimated.Furthermore,it was manifested that effective measures,i.e.,fast mining,control symmetrical top-coal-caving at dip and strike directions,optimizing ventila- tion system,active-stereo preventing gas were performed successfully in mining practice. Ultimately,the derived dynamic hazard were prevented so as to safety mining.

Reconnaissance Geophysical Study on the Southeastern Part of Al-Qashah Aera, KSA

The investigated study area locates about 72 km from Jeddah City, Makkah District, Kingdom of Saudi Arabia. The study mainly aimed to define the most significant zones of possible mineralization and outline their subsurface parameters (location and strike) in the southeast of Jabal Al-Qashah. Several geophysical methods have been conducted to carry out the goal, including ground magnetic, self-potential (SP), and induced polarization (IP) methods. Integrating these methods aims to help delineate the possible mineralization in the study area. The magnetic survey was conducted along 17 profiles where these profiles were chosen to be perpendicular to the strike of the quartz shear zone. Self-potential was applied along with five profiles covering the study area. At the same time, induced polarization was used along with one profile located at the western side of the study area corresponding to some magnetic and SP profiles. The most interesting zones of mineralization were successfully determined by comparing the results of residual magnetic profile (3), SP profile (1), and IP profile, where geological structures control some mineralization.

Elaboration of the Hydro-Geophysics GIS Showing the Volubilis Depression and the Prerifains Ridges Structuration (Morocco North Occidental)

We present a comparative analysis of electrical and gravity data on the Geographic Information System of the prerifaines ridges. At the Meso-Cenozo?c sequence, the geometry of the prerifaines ridges is fairly well known. However, the post-Miocene series remain to be characterized. In this perspective, we use a database composed of gravity and vertical electrical sounding profiles and geo-electrical sections in order to characterize this structuration. These data are calibrated by many oil and hydrogeological boreholes. Preliminary results lead to better understanding of the organization of its underlying structures in this area. The Gravimetric filtering results show that the area may be dissected by tree major faults striking NW-SE, NE-SW and N-S. All these faults have contributed, since Hercynian to Alpines orogenies, to the structuring of this area, being proved to be the deepest and can reach 4500 m. The comparison of gravity maps, geological and structural maps under Geographic Information System allows the identification of major structural directions and trends of the study area. It confirms some structural elements gathered from outcrops and define new ones. Results from this work show the importance of using various filtering and interpretation techniques in the analysis of gravity data. They also provide news insights into the deep structure of the study area.

Research progress in geophysical exploration of the Antarctic ice sheet

The Antarctic ice sheet is an important target of Antarctic research.Thickness and structure,including intraice and subice,are closely related to the mass balance of the ice sheet,and play an important role in the study of global sea level and climate change.Subglacial topography is an important basis for studying ice sheet dynamics and ice sheet evolution.This paper briefly reviews the geophysical detection methods and research status of the Antarctic ice sheet:(1)Conventional methods such as ice radar are the main methods for studying the ice sheet today,and passive source seismic methods such as the receiver function method,H/V method and P-wave coda autocorrelation method have good development prospects;(2)the high-resolution(1 km)ice thickness and subglacial topographic database BEDMAP2 established based on various data has greatly improved the ability to detect internal isochronous layers,anisotropic layers,and temperature changes within ice and has advanced research on ice sheet evolution;and(3)ice radar,numerical simulation and core drilling are the main methods to study subglacial lakes and sediments.More than 400 subglacial lakes have been confirmed,and more than 12000 simulation results have been obtained.Research on the Antarctic ice sheet faces enormous challenges and is of great urgency.Aiming at hot issues,such as Antarctic geological evolution,glacial retreat,ice sheet melting and their relationships with global climate change,it is the frontier and trend of future Antarctic ice sheet research to carry out multidisciplinary and multicountry comprehensive geophysical exploration based on the traditional ice radar method combined with passive seismic methods,especially new technologies such as short-period dense array technology,unmanned aerial vehicles and artificial intelligence.This is expected to further promote Antarctic research.

Recent advances in petrophysical and geophysical characterization of unconventional resources:Introduction

As a bridge between the reservoir performance and the geophysical well logging data,petrophysical measurements and its characterization are very important for the exploration and development of the unconventional resources in tight sandstone,carbonate and shale reservoirs.In this special issue of Energy Geoscience,“Recent advances in petrophysical and geophysical characterization of unconventional resources”,we organized and invited authors to present recent advances in various subjects addressing new petrophysical characterizations and geophysical models in unconventional reservoirs.

Journal of Geophysics and Engineering(JGE)国内主办的被SCI检索的国际性专业英文科技期刊

由中国石化石油勘探开发研究院南京石油物探研究所主办,英国帝国理工大学油藏地球物理研究中心协助编辑出版的国际性地球物理与工程专业英文科技期刊JournalofGeophysicsandEngineering(JGE)于2004年出版。委托英国物理学会出版社印刷并在全球发行。该刊在国际标准序列刊号(ISNN)英国中心申请的印刷版刊号为ISSN1742-2132,电子版刊号为ISSN1742-2140。JGE设有3个编辑部,分别位于中国南京石油物探研究所、英国帝国理工大学油藏地球物理研究中心和英国物理学会出版社。今年4月,JGE编辑部收到美国科技信息研究所(ISI)的函件,被告知期刊自创刊起即被该所以下数据库收录:①包括ISI网络检索数据库(WebofScience)在内的科学引文索引扩展版(SCIE);②ISI最新资料快报;③期刊题录快讯/工程,计算和技术数据库(CC/EC&T);④期刊题录快讯/物理,化学和地球科学数据库(CC/PC&ES)。ISI是全球知名的最有影响力的信息研究机构。每年收录近2000种新刊物,但是只从数据库中挑选10%-12%的刊物进行评估。

Spatial Discrimination of Complex, Low-Relief Quaternary Siliciclastic Strata Using Airborne Lidar and Near-Surface Geophysics： An Example from the Texas Coastal Plain, USA

保存在全球滨海平原上的沉积单元控制着浅地层岩性分布,这对基础设施的设计和建设至关重要,同时也是许多第四纪冰期—间冰期循环中发生大规模气候变化的重要信息库。我们对这些沉积单元的横纵向岩性、地层复杂性及其对气候和海平面变化的响应知之甚少,因此很难预测岩性分布,以及将发展历史、未来气候和海平面变化置于同一自然地质环境中。传统上在低幅度滨海平原上描绘的第四纪硅质碎屑沉积单元建立在航拍图和低分辨率地形图的基础上。低幅度和低曝光率影响了观测的准确性和精确性。高分辨率机载激光雷达探测、地表地球物理勘探和地球物理测井正被用于识别得克萨斯州滨海平原上第四纪地层岩性单元的精确横纵向边界。地表和井中电导率测量能从泥质泛滥平原、三角洲平原和河道沉积中区分出砂质障壁岛、河流和三角洲河道沉积物。井中电导率和自然伽马测井记录同样可以区分地下不同的岩性单元,并识别出可能在不同冰期-间冰期阶段分离的沉积单元的侵蚀不整合面。从机载激光雷达探测获得的高分辨率数字高程模型揭示了以前不为人知的地形细节,有助于识别地表特征,如砂质通道、富含黏土的河间沉积和更新世障壁岛上的堆积特征。在低幅度滨海平原环境中识别岩性和地层分布的最佳方法是:(1)首先使用激光雷达探测生成详细的高程模型;(2)基于激光雷达数据和航拍图的初步定位,选择性进行地表采样和地球物理探测;(3)在激光雷达和地表探测完成后,选择关键位置进行钻孔取样、测井和分析。