DETECTION OF CAVES IN A KARST FORMATION BY MEANS OF ELECTROMAGNETIC WAVES*

The application of classical geophysical methods in locating karst caves did not yield always unambiguous results. It was our task to verify a new method that has not yet been tested. In investigating caves in a karst formation, electromagnetic waves in the band 2–10 MHz were applied. The physical analysis of the problem is carried out, the measuring device used for the perradiation of the rocks between the boreholes is described, and the results of the measurements made in the karst area of East Slovakia (?SSR) are shown. The verification from mines is included. The results mentioned are demonstrated in a space model. The work performed in the mines verified unambiguously the interpretation of the indications measured. The results show the suitability of putting the electromagnetic method in question into the set of geophysical methods within the hydrogeological survey of karst areas.     

西部地下水勘查的基础地质问题与关键地球物理技术

介绍了基础地质问题研究对西部深层地下水文地质研究的重要意义，就西部地下水研究的特殊性，针对性地提出了地球物理的解决方法和思路，在利用已有的地球物理资料研究基础地质问题的过程中，介绍重要的地球物理方法技术及研究工作步骤，针对这些方法技术在应用中面临的问题和技术本身存在的不足，提出了具体解决方案和研发部署，针对已有资料的局限性和西部地下水的特殊性，提出研究高精度地震静校正、全波处理等方法技术。     

中国油气资源企盼二次创业

中国石油天然气工业在过去50年的第一次创业中，主要是在新生年代陆相沉积盆地中获得丰富的油气资源，当前在严峻的形势下，国家必须进行油气资源的第二次创业，第二次创业要从突破前新生代（中生代、古生代、甚至更早）海相碳酸盐岩地层中的油气开始，解放思想，提高认识并大力发展地球物理勘探技术，努力解决复杂地质体成象问题，探索海相油气资源，使这次创业得以成功。     

西部地下水资源勘查的综合地球物理问题-以鄂尔多斯盆地白垩系地下水勘查为例

西部地下水资源勘查不再是单纯的地理、地质和水文方面的问题。由于地下水的深赋存性质，决定了西部地下水的勘查与油气勘探一样，是深层的地球物理问题。地下水研究所涉及的基础地质问题、地层的含水性问题和水质问题是目前地下水水文地质研究的关键。这三个问题的有效解决，必须依靠勘探地球物理方法技术的有效运用和新方法、新技术的研究开发。本文在阐述地下水水文地质研究现状和面临问题的同时，就目前地球物理勘探技术的发展水平和在西部的发展状况，以鄂尔多斯盆地地下水勘查为例，提出了利用已有物探资料为地下水勘查服务的地球物理解决方案，从理论方法上证明其可行性，并提出了建立示范区研究的必要性，以期对目前正兴起的西部水资源研究提供参考。     

物探方法在水库坝基渗漏勘探中的应用

近年来物探方法在坝基勘探、活断层探测、溶洞探测和基础检测等工程中得到广泛应用,并取得了令人瞩目的成绩。本文介绍了在某水库坝基渗漏勘探开展物探工作的情况,取得了满意的结果,表明应用多种物探方法对解决工程问题具有较好的效果。     

新疆玛纳斯县石门子水库诱发地震初步探讨

论述了新疆维吾尔自治区玛纳斯县塔西河石门子水库的地质构造、地层岩性、构造应力场,地震活动背景以及水文地质条件,对水库地震诱震的各种因素与已发生水库地震的实例进行了分析,尤其是对天山地区与石门子水库地质构造要似的努列克和克孜尔水库和诱震诺因素作了讨论,得出的结论是拟建的石门子水库蓄水后诱发地震的可能性是比较小的。     

南水北调西线千米深长隧洞围岩构造地球物理勘探

2004年对南水北调引水隧洞西线一期工程中玛柯河－贾曲段20 km深埋长隧洞进行了地质结构面、岩性特征、赋水性等地球物理勘探、工程地质勘查,并进行综合解释以查清勘探区影响引水隧洞工程建设的不良地质体和不良地质构造.本文介绍了CSAMT法隧洞勘探的特点、资料采集的过程及应特别注意的复杂地形资料处理技术,结合其他补充物探手段及地面工程地质勘察结果对20 km深埋长隧洞围岩介质的结构特征进行了解释,指出了可能影响工程的断层、破碎带及异常区     

花县的地质灾害及防治对策

本区主要地质灾害包括岩溶塌陷、地裂缝、岩溶突水。这些灾害破坏地面、农田、民房和工程构筑物,影响居民和工业用水。灾害产生的内因是地下存在可溶性岩层,构造及岩溶裂隙发育无稳定隔水层,局部存在膨胀土,岩溶水与地表水沟通。近年大量开采岩溶水,迅速改变地下水动力状态对灾害的发生起了触发作用。防止过量抽取地下水、防止大量排走地表水、加强地质勘查、依场地条件确定工程建筑位置、类型并作必要的地基加固处理系防治本区地质灾害扩展的有效途径。     

Hydrogeological investigation of karst system properties by common use of diverse methods: a case study of Lička Jesenica springs in Dinaric karst of Croatia

Li?ka Jesenica is a sinking river situated in the Dinaric karst environment of the Lika region of Croatia. The two main karst springs, Veliko Vrelo and Malo Vrelo, provide the majority of Li?ka Jesenica's water. Because of the quality and abundance of the water they contain, these springs are strategically important to the public water supply. Previous knowledge regarding the springs` karst system has been negligible. Therefore, a bulk hydrogeological research program was conducted with the purposes of establishing protection zones and assessing the springs' water‐supply potential. The research work comprised the following methods: hydrogeological mapping, setting up of monitoring stations for evaluating discharge and water quality, time series analyses (hydrograph–chemograph), hydrochemical analyses, and geophysical surveys. The main results and conclusions of the research include the following: (i) confirmation that both springs drain a common aquifer; (ii) determination of the highly vulnerable nature of the karst systems; (iii) identification of the Veliko Vrelo Spring's more direct connection to the aquifer‐drainage system in comparison to the Malo Vrelo; (iv) estimation of the positions and depths of the springs` main feeding conduits; (v) confirmation of the extent of the geologically presumed catchment area; and (vi) finally, establishment of sanitary protection zones. Copyright © 2012 John Wiley & Sons, Ltd.     

RIS时空分布特征及其与库区地质构造环境的关系

在广泛收集了国内外水库诱发地震震例资料的基础上,利用统计学的方法,进行了水库诱发地震空间分布与时间响应特征及其与库区地质构造环境关系的研究,结果表明:①在空间分布上,诱发地震主要集中在水库周缘10 km范围之内,并局限于特定的库段丛集分布,当库区具备一定的地质构造与水文地质条件时,诱发地震活动会随着水库蓄、放水过程中的水位变化而发生迁移;②对于不同地区或不同水库,诱发地震活动的时间响应存在着差异,总体上:在水库蓄水后1年以内,初次响应占据一定的优势,而绝大部分诱发主震活动发生在水库初始蓄水1年以后。对长时间的水库蓄水历程而言,"混合响应"是水库诱发地震活动表现形式的主体,而"快速响应"和"滞后响应"仅是在一定的时间段内反应的阶段性现象;③诱发地震响应与水库水位变化的关系十分复杂多样,既存在正相关关系,又有负相关性,同时在某种程度上表现出了较高震级的水库诱发地震对水位变化速率的依赖;④水库诱发地震时空分布受发震库区地形地貌与局部地质构造条件、岩性条件、水文地质条件等方面的先存内因的控制,事实上,它们对水库诱发地震时空分布的控制作用并不是截然分开的,其间存在着相互依存、辩证统一的关系。     

PROSPECTING FOR SUBSURFACE WATER IN THE CENTRAL VOLCANIC HIGHLAND OF ARMENIA BY GEOPHYSICAL METHODS*

Work carried out in several volcanic areas in Armenia has led to a combination of geophysical methods for hydrogeological problems. Prospecting of interlava and sublava water flows is done by electrical profiling and vertical electrical sounding. When mapping the relief of sublava water-resisting rocks, the electrical sounding (ES) method is widely used. This is based on the evaluation of lava resistivity. The method discussed allows to determine the most probable value of this parameter, by using statistical methods.     

工程物探中地震层析成像的研究

从实际情况出发，讨论工程中应用地震层析成像方法几个环节中的一些具体问题，包括资料采集中观测系统的装置，原始资料的分析和预处理，以及资料处理时如何选择合适的参数等。文中提出的扫描法、快速搜索法等弯曲射线校正方法克服了以往方法计算量大、存在盲区等缺点。反演实测资料效果良好。     

Groundwater exploration using integrated geophysical techniques

The integrated approach to solving complicated geological, hydrological and environmental problems is now widely used in geophysics. Among all the geophysical methods, electrical and electromagnetic techniques are the most popular in groundwater exploration due to the close relationship between electrical conductivity and some hydrogeological properties of the aquifer (e.g. porosity, clay content, mineralization of the groundwater and degree of water saturation). Case histories presented here show that by proper combination of different techniques such as conventional direct current (DC) resistivity as well as the more advanced electromagnetic (EM) methods and the most recent nuclear magnetic resonance (NMR) tomography, the reliability of interpretation as compared to that typical for the individual methods can be significantly improved.     

RESISTIVITY AND MAGNETIC SURVEYS IN GROUNDWATER PROSPECTING IN VOLCANIC AREAS—CASE HISTORY MAAR OF BEAUNIT,PUY DE DOME,FRANCE*

Volcanic maar structures sometimes contain important groundwater reserves. The volcanic formations of the Beaunit maar have a much higher magnetization than their granite substrata. The structure of the maar and its volcanoclastic infill can therefore be defined by magnetic surveying and resistivity soundings. Resistivities of the geological formations present in the Beaunit maar are comparable to those recorded in other volcanic systems. The geophysical data, confirmed by drilling tests, contain useful information on the hydrogeological regime of the volcanic system under investigation.     

Dissolution-filling mechanism of atmospheric precipitation controlled by both thermodynamics and kinetics

Affected by structural uplift,the Ordovician carbonate rockbed in the Tarim Basin,China,was exposed to dissolution and reformation of atmospheric precipitation many times,and formed a large quantity of karst caves serving as hydrocarbon reservoir.However,drilling in Tahe area showed that many large karst caves,small pores and fractures are filled by calcite,resulting in decrease in their reservoir ability.Calcite filled in the karst caves has very light oxygen isotopic composition and87Sr/86Sr ratio.Its 18OPDB ranges from 21.2‰to 13.3‰with the average of 16.3‰and its87Sr/86Sr ratio ranges from0.709561 to 0.710070 with the average of 0.709843.The isotope composition showed that calcite is related to atmospheric precipitation.Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms.Among them,the thermodynamic factor determines that the precipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to saturation,further sedimentation,and finally filling.In other words,the depth of the karstification development is not unrestricted,but limited by the precipitation beneath the earth surface.On the other hand,the kinetic factor controls the intensity,depth,and breadth of the karstification development,that is,the karstification is also affected by topographic,geomorphologic,climatic factors,the degree of fracture or fault,etc.Therefore,subject to their joint effects,the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth(most about 200 m)under the unconformity surface,deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.     

工程物探中若干问题探讨

本文针对工程物探中主要任务与要求，着重讨论了查找陷伏断层，鹇基岩面及其风化壳的划分，第上系分层等问题，分析当前常用物控方法的有效性，探讨提高勘查能力，合理选用方法的途径，文中以直流电法，电磁法，声纳法和地震法等的应用实例进行对比，阐述它们的应用前提并对其进行评价。说明充分了解各工区的地质地球物理特征及工作前的方法技术试验是不容忽视的基础工作。     

Validating the KAGIS black‐box GIS‐based model in a Mediterranean karst aquifer: Case of study of Mela aquifer (SE Spain)

Karst Aquifer GIS‐based model (KAGIS model) is developed and applied to Mela aquifer, a small karst aquifer located in a Mediterranean region (SE Spain). This model considers different variables, such as precipitation, land use, surface slope and lithology, and their geographical heterogeneity to calculate both, the run‐off coefficients and the fraction of precipitation which contributes to fill the soil water reservoir existing above the aquifer. Evapotranspiration uptakes deplete water, exclusively, from this soil water reservoir and aquifer recharge occurs when water in the soil reservoir exceeds the soil field capacity. The proposed model also obtains variations of the effective porosity in a vertical profile, an intrinsic consequence of the karstification processes. A new proposal from the Nash–Sutcliffe efficiency index, adapted to arid environments, is presented and employed to evaluate the model's ability to predict the water table oscillations. The uncertainty in the model parameters is determined by the Generalized Likelihood Uncertainty Estimation method. Afterwards, when KAGIS is calibrated, wavelet analysis is applied to the resulting data in order to evaluate the variability in the aquifer behaviour. Wavelet analysis reveals that the rapid hydrogeological response, typical of a wide variety of karst systems, is the prevailing feature of Mela aquifer. This study proves that KAGIS is a useful tool to quantify recharge and discharge rates of karst aquifers and can be effectively applied to develop a proper management of water resources in Mediterranean areas.     

电阻率层析成像法在辽阳活断层探测中的应用

电阻率层析成像法是近年来迅速发展起来的地球物理新技术,目前逐渐成为工程物探中的主要方法。在辽阳市地震活断层与地震危险性评价研究中运用该方法取得了良好的效果。通过在目标区布设探测剖面,辅以浅层地震,地质钻探,可以准确地探测断层的几何结构和物理特征,为辽阳市活断层探测与地震危险性评价研究提供准确可靠的物探依据。     

Quantitative geophysical pore‐type characterization and its geological implication in carbonate reservoirs

This paper discusses and addresses two questions in carbonate reservoir characterization: how to characterize pore‐type distribution quantitatively from well observations and seismic data based on geologic understanding of the reservoir and what geological implications stand behind the pore‐type distribution in carbonate reservoirs. To answer these questions, three geophysical pore types (reference pores, stiff pores and cracks) are defined to represent the average elastic effective properties of complex pore structures. The variability of elastic properties in carbonates can be quantified using a rock physics scheme associated with different volume fractions of geophysical pore types. We also explore the likely geological processes in carbonates based on the proposed rock physics template. The pore‐type inversion result from well log data fits well with the pore geometry revealed by a FMI log and core information. Furthermore, the S‐wave prediction based on the pore‐type inversion result also shows better agreement than the Greensberg‐Castagna relationship, suggesting the potential of this rock physics scheme to characterize the porosity heterogeneity in carbonate reservoirs. We also apply an inversion technique to quantitatively map the geophysical pore‐type distribution from a 2D seismic data set in a carbonate reservoir offshore Brazil. The spatial distributions of the geophysical pore type contain clues about the geological history that overprinted these rocks. Therefore, we analyse how the likely geological processes redistribute pore space of the reservoir rock from the initial depositional porosity and in turn how they impact the reservoir quality.