北黄海盆地烃渗漏蚀变带“磁亮点”的识别研究

北黄海盆地是我国近海海域尚未取得油气勘探突破的盆地之一.在海洋环境中应用海底油气藏的烃渗漏现象寻找油气有利区具有良好应用前景,为了给该区的含油气远景评价及下一步油气勘探缩小靶区提供地球物理依据,本文利用磁法这一经济、有效的油气渗漏异常地球物理判别手段,开展了识别海底烃渗漏引发磁异常的方法研究.给出一种根据“有导师”的模式识别技术,在充分利用磁异常多种数值特征及纹理特征的基础上,提取烃渗漏蚀变带磁异常的方法.通过已知约束信息（如见油井位等）的点、线、面三种基元及其邻近数据网格点组成基类,将其提取的模式或特征向量作为待识别异常匹配或学习的模板,利用加权欧氏距离函数计算待识别异常特征向量与模板向量之间的相似性,进行模式匹配,从而识别出与模板相似程度较高的异常.应用此方法圈定了北黄海盆地的烃渗漏“磁亮点”分布,从“磁亮点”异常区与中生代地层的分布以及地球化学异常（低层大气烃类检测和海底微生物异常）的对应情况来看,表明该识别方法是识别烃渗漏弱磁异常的一种有效手段.对研究区构造特征、磁异常及地球化学异常特征的综合分析表明,位于北黄海研究区东部和北部的“磁亮点”异常区可能是北黄海盆地较好的含油气远景区.     

海洋油气渗漏烃蚀变带的地球物理检测及在中国海区的应用

针对海洋油气渗漏可以在近地表沉积层中引起的一系列烃蚀变效应，本文讨论了利用不同手段，分层次进行检测的几种方法.利用烃蚀变带所产生的磁异常现象，在平面上圈定油气渗漏的分布范围，进而寻找海底油气藏.同时，钻井岩芯岩屑的磁性质测量结果可以从剖面上预测下伏岩层的含油气性.最终利用X射线衍射方法(XRD)对典型层位岩石样品的物相测量，进行烃蚀变矿物组合分析并通过镜下鉴定作进一步的综合判断.对渤海海域烃蚀变效应的磁法检测研究结果与遥感及其他方法的研究结果有很好的一致性.对南海3口钻井岩芯岩屑的磁性测量结果表明：两口有油气前景而另一口没有异常.这与实际结果十分一致，同时表明该方法在海区同样可以具有良好效果.     

磁测找油方法及其在陕北油气勘探中的应用

二十多年来,磁测找油方法作为非地震油气物探方法中的一种,在陕北油田进行了大量的试验及研究工作.为了系统归纳磁测找油方法研究进展及探讨其在陕北油气勘探中的应用效果,本文阐述了油气藏上方近地表微磁异常的形成机理以及磁性矿物的形成机制的研究进展,总结了由于地下油气藏的存在而引起的微磁异常的一般特征,分析了陕北吴堡-旦八地区已有油井及干井的分布特征与高磁剩余异常特征间的关系.结果表明,油气藏上方岩石中广泛存在的磁学-地球化学-矿物学异常与烃类微渗漏作用之间的相互关系基本可以成立,烃渗漏可以通过改变油气藏上方空间氧化还原条件等造成磁性变化从而在近地表产生磁异常变化,而这些磁异常在经过数据处理之后,可以提供微磁异常与油气藏之间高度的相关性.陕北吴堡-旦八地区高磁剩余异常与油井具有一定的相关性,高频、低幅度、高值异常带以及高值环带包围低值区块的环带异常与油气藏有较好的对应关系.虽然目前还不可能研究出一种可以完全消除或大部分压制地面上各种人文干扰产生磁场的方法技术,但是在开展高精度磁测工作时,尽量压制各种与油气藏无关的干扰磁异常,并且做好物性测定和样品分析,磁测找油方法仍不失为一种经济、快速、有效的方法.     

海底流体逃逸活动的地球物理响应特征

海底流体逃逸活动对海洋油气勘探、天然气水合物勘查和试采、海底固体矿产勘探与全球气候变化研究等方面具有重要意义.理解海底流体逃逸活动规律,研究流体逃逸活动演化过程,并建立综合探测体系显得尤为重要.本文系统梳理了海底流体逃逸活动在海底可视技术、综合声学水体成像技术、"磁亮点"技术以及卫星遥感技术等相关探测方法下的不同地球物理响应.分析认为,海底流体逃逸活动容易改变海底地层的物理性质和形态,在地震剖面和声学图像上表现为独特的流体异常反射特征和声学响应;烃渗漏形成烃蚀变带,在航磁图像上表现为弱磁异常;渗漏油膜在SAR卫星图像上表现为黑色斑块;天然地震控制下的断裂带流体逃逸活动在临震时震中附近在热红外图像上表现为亮温异常.结合不同探测方法的探测效率和优势特征,提出了利用卫星遥感和"磁亮点"等方法进行平面约束预测,用剖面或立体声学水体成像数据进行海底流体活动确认,再通过海底可视数据进行精细探测的综合地球物理探测方法,为深入研究海底流体活动系统理论提供参考,同时指出流体逃逸活动研究的相关方向.     

西秦岭国安寺—白杨沟地区高精度磁测异常特征及找矿远景分析

研究区位于西秦岭东段的凤太矿集区内.在系统搜集和研究陕西凤太地区前人地质资料成果的基础上,结合本次1/5万地面高精度磁法测量资料,以金、铅锌矿为主要目标,整体评价研究区矿产资源潜力.研究区地面高精度磁测结果表明:该区自西向东可分为西部正磁异常区、中部平静磁异常区和东部负磁异常区,弱磁异常与区内广泛分布的沉积地层有关,"西高东低"的磁场变化特征与磁性基底的起伏形态有关.共圈定17处磁异常,磁异常按从西到东、由北往南的顺序依次进行编号,分别为M1、M2……M17,这些磁异常有的与磁性基底有关,有的属于隐伏磁性体,有的与磁黄铁矿化蚀变有关,其中磁黄铁矿化蚀变间接对寻找区内八卦庙式金矿具有指示意义.通过对全区磁异常特征的研究并结合相关地质资料,划分成矿远景区两处,为以后找矿提供思路分析,可作为寻找铅锌金-多金属矿的远景区.     

坦桑尼亚凯巴卡瑞地区构造蚀变岩型金矿航磁异常特征与找矿意义

坦桑尼亚是东非第一产金大国,构造蚀变岩型金矿是该国的一个重要金矿床类型,该类型金矿床与断裂构造中的构造蚀变带密切相关,主要分布在坦桑尼亚环维多利亚湖东部、西南部及东南部绿岩带中;凯巴卡瑞地区内岩石磁性表现为强-中-弱-微或无的强度等级,岩石相互之间磁性差异明显,其航磁异常显示的地质信息比较详尽,反映的磁性地层、岩体界线清晰,线性构造特征明显.依据坦桑尼亚凯巴卡瑞地区尼亚斯罗利金矿床上的航磁异常表现形式,对凯巴卡瑞地区航磁异常强度、规模、形态及延伸等特征进行了认真分析和对比研判,认为该区域航磁异常客观地反映了与构造蚀变岩型金矿有关联的断裂构造和绿岩分布区,构造蚀变带、金矿脉以及所赋存的绿岩地层在航磁异常上表现为低强度磁异常,其他岩石(条带状铁建造、辉绿岩、花岗岩)在航磁异常上表现为高强度磁异常,据此选择的找矿靶区通过地面物探方法(高精度磁测、微磁测量)查证,取得了明显的找矿效果;凯巴卡瑞地区航磁异常解译厘定的地质信息,为进一步预测成矿区域、圈定找矿靶区及间接发现构造蚀变岩型金矿床奠定了基础,因而预判坦桑尼亚凯巴卡瑞地区分布的航磁异常具有寻找构造蚀变岩型金矿的较大潜力.     

微磁测量在坦桑尼亚构造蚀变岩型金矿床上的应用研究

构造蚀变岩型金矿床是坦桑尼亚绿岩带重要的金矿床类型.金矿脉和它所赋存的构造蚀变带与周围背景岩石磁性差异较小,高精度磁测难以反映出构造蚀变带和金矿脉引起的微弱磁场特征,为了获取构造蚀变带和金矿脉引起的精细磁场结构,在选择的单元测区(主要矿脉分布区)内进行了高密度、高精度、高分辨微磁测量(20 m×5 m)精细研究;微磁异常清晰地反映了构造蚀变带和金矿脉群引起的磁场特征,为钻探工程布置提供了充分的依据,起到了良好的找矿效果.研究认为寻找构造蚀变岩型金矿的微磁测量流程为:(1)开展1∶1万地面高精度磁力扫面测量,大致圈定找矿靶区和选择单元测区;(2)单元测区内进行微磁测量,获取精细地磁场结构;(3)微磁异常上布置微磁剖面测量(点距2 m),定位构造蚀变带和金矿脉.微磁测量对坦桑尼亚其他绿岩带以及我国(乃至世界)绿岩带地区寻找构造蚀变岩型金矿也具有良好的示范和指导意义.     

北天山地震带的航磁异常与深部构造

通过分析天山和邻近地区的航磁资料，划分出了４个较大的具有不同基底性质和深部构造特征的磁异常区。天山地区的地震大多数都发生在基底隆起或坳陷的附近，在深部磁场图像中，它们则位于天山高磁性块体与周围弱磁性区域之间，那里不仅是正负磁异常的转换带，而且是明显的大地构造边界。介质的磁性与其它地球物理资料一样，也是反映地震活动区域深部构造的一个重要标志。     

黄土覆盖区钼矿综合地球物理找矿技术组合:以沙坡岭钼矿为例

覆盖区寻找隐伏矿成为当前找矿工作的热点问题,为了能在地表地质信息少的黄土覆盖区,寻找隐伏的有经济价值的矿床,本文以沙坡岭钼矿为例,综合应用r能谱、高精度磁法、高密度电法三种地球物理方法进行找矿勘探,辅以偏提取化探法对地球物理异常进行约束,结合地质资料进行解译,预测了有利的成矿区域,通过钻探得到了有效验证,初步建立了黄土覆盖区钼矿的综合地球物理找矿模式,为下一步的综合勘探打下了基础.     

反演磁性地质界面的意义与方法

磁性地质界面的反演是地球物理勘探的重要课题之一,对于提高磁测资料的地质解释效果有重要意义.通过磁测资料反演磁性地质界面主要分两步：第一步,从总异常中分离有磁性界面起伏引起的磁异常;第二步,由分离的磁异常反演磁性界面的深度.本文分别从这两个方面回顾了提取异常和反演界面的较有代表性的技术.     

近表磁异常与油气关系研究进展

本文对近年来国内外科学界关于油气产区与近表磁异常关系的研究进行论述。认为国外一些科学家提出的磁亮点以方法以及钻探岩芯及岩屑中的ＭＳＲＩ参数法都是新颖有效的。它为我们提供了一个新的思路,即从油气藏的烃渗漏问题入手,寻找与其有关的相关标志,来自国外的一些报导证实了磁性变化与油气资源间较高的相关性。而我国科学院家们在塔里木等地的工作,则进一步证实了方法的有效性。     

烃渗漏引起的磁异常的提取与识别

本文对近年来国内外在烃渗漏与磁异常关系以及磁异常提取与识别技术领域取得的进展进行了论述与总结.利用磁异常寻找油气资源,特别是在圈划异常远景区方面具有经济、快速、有效的优势.但也存在多解性问题.为了有效判别异常源性质,本文提出利用人工神经网络作为以上方法补充的思路,可以作为磁法预测油气远景区技术流程中的一环,有助于减少多解性.     

核磁共振测井技术在桩海地区及其它油田中的应用

阐明核磁共振测井（NMR）在储层评价中的作用。利用NMR测井资料对桩海地区长堤油田的储层特性及产能、复杂岩性储层的孔隙度作出评价，并在电阻率测井资料显示不好的复杂储层条件下进行油气水层识别，以及指导完井和钻井方案的实施等。不阐明了核磁共振测井技术具有常规测井技术所不具备的特点，特别是定量的评价孔隙流体流动特性、准确划分产层、直接识别油气水等优点，从而有利于解复杂的地质问题。     

The application of rapid potential field methods for the targeting of IOCG mineralisation based on physical property data,Great Bear magmatic zone,Canada

New techniques for the integration of gravity and aeromagnetic data through rock physical property relationships are tested for the rapid location of potential iron oxide–copper–gold (IOCG) exploration targets across the Great Bear magmatic zone (GBMZ). These techniques are based on the recognition of coincident or near-offset magnetic and gravity anomalies associated with IOCG deposits, resulting from their intense and combined iron-oxide and alkali alteration. In the GBMZ, the NICO (Au–Co–Bi–Cu) deposit is an atypical magnetite-group IOCG hosted within an intensely hydrothermally-altered metasedimentary sequence. Prospectivity maps for the NICO area are derived from the integration of high-resolution aeromagnetic and surface gravity data with physical property measurements of magnetic susceptibility and density. Method 1 combines the pseudo-gravity (derived from the aeromagnetic data) and Bouguer gravity data to determine the locations of superimposed high anomalies. Method 2 estimates the apparent susceptibility and density subsurface distribution based on vertical prism models of the magnetic and gravity data. The apparent susceptibility data are transformed to apparent density using physical property relationships. The two apparent density datasets are then combined to determine the location of coincident magnetic and gravity derived anomalies. The results of these methods are supported by, and compared with, similar prospectivity maps generated through weights of evidence techniques. At NICO, the prospectivity maps accurately locate the deposit and nearby occurrences. Despite the lower resolution of the regional gravity data, application of the techniques across the GBMZ is successful at locating mineralised IOCG systems including the magnetite-group systems at Grouard, Fab, DeVries and Cole Lake, the magnetite to hematite-group systems of the Port Radium-Echo Bay district, and has highlighted possible targets for future exploration.     

某些油气田地表土壤的磁性与烃运移相互关系研究

根据鄂尔多斯盆地靖边气田上方的ＭＩ０２线、江苏储家楼油田与江汉盆地花园油田地表十字剖面土壤磁性的测量结果，研究地表是否存在与深部油气藏中烃类垂向运移相关磁性蚀变带的可能性及其分布形式．结果表明，ＭＩ０２线样品显示了明显的高磁性异常特征，并与酸解烃之间呈很强的正相关．磁滞回线形态与参量显示出明显的亚铁磁性特征．电子探针分析结果表明，样品中主要磁性矿物（磁铁矿）中高温杂质元素含量很低．江汉盆地花园油田十字剖面磁滞回线参量（饱和磁化强度Ｊｓ与饱和等温剩磁Ｊｒ）的高异常位于油田周边，油田顶部土壤呈典型顺磁性特征．储家楼油田地表土壤的高磁性异常主要位于油田上方，它们均与盖层中的断裂构造对应，储家楼油田的高磁性样品中发现的典型球粒状磁铁矿为次生低温磁铁矿，它与烃运移之间存在成因关系．     

Petroleum Electromagnetic Prospecting Advances and Case Studies in China

Remarkable progress has been made in electromagnetic (EM) techniques as applied to the petroleum industry in instruments, data acquisition, and processing and interpretation in China. Included here is equipment, such as high-power Controlled Source EM (CSEM) acquisition systems, acquisition methods, such as the three dimensional small-bin Continuous Electromagnetic Array acquisition method, Time and Frequency Domain Controlled Source Electromagnetic, Borehole-to-surface Electromagnetic technique and marine magnetotelluric method. Data processing methods, such as fast three dimensional inversion using nonlinear conjugate gradients, and data interpretation methods, like Induced Polarization and Resistivity anomalies for hydrocarbon detection, are also included. These new techniques have been applied in petroleum survey and many cases are in complicated areas. They have successfully served the investigation of deep igneous rock reservoirs, and prediction of potential hydrocarbon targets. The cases indicate that electromagnetic techniques can help seismic survey to effectively detect hydrocarbon reservoir and remarkably improve drilling successes.     

Gravity and magnetic field characteristics and hydrocarbon prospects of the Tobago Basin

The Tobago Basin, which is located offshore northern Venezuela with a southern margin close to Trinidad and Tobago, has an area of approximately 59,600 km². The Tobago Basin has relatively favourable hydrocarbon prospects, and to date, exploration work has mainly concentrated on small areas of the southwestern portion of the basin. To conduct a comprehensive study of the structural framework of the basin and the characteristics of the basement in order to identify prospective zones for hydrocarbon exploration, shipborne‐measured and satellite‐measured gravity data, shipborne‐measured magnetic data, and aeromagnetic survey data were analysed. A regularisation filtering method was used to separate and obtain regional and residual gravity and magnetic anomalies. Directional gradients of gravity and magnetic anomalies and the total horizontal gradient and vertical second derivative of gravity anomalies were employed to extract information about fault structures. Regression analysis methods were used to determine the basement depth. The geological significance of the gravity and magnetic fields was examined, the structural framework of the basin was assessed, the basement depth was estimated, and favourable hydrocarbon exploration prospects within the basin were identified. The results show that the Tobago Basin contains complex structures consisting mainly of two groups of faults trending in northeasterly and northwesterly directions and that the major northeasterly trending faults control the main structural configuration and depositional system within the basin. The basement of the Tobago Basin has deep rises and falls. It can be divided into the following four secondary tectonic units: the western sub‐basin, the central uplift area, the southern sub‐basin, and the northeastern sub‐basin. The central uplift area and northeastern sub‐basin are most likely to have developed hydrocarbon accumulations and should be targeted for further exploration.     

Geophysical targeting of Fe-oxide Cu–(Au) deposits west of Kiruna,Sweden

Ore deposits are frequently associated with various types of rock alteration that may affect the physical properties of rocks, and result in a characteristic signature of the deposits. The present work focuses on the use of geophysical data in targeting areas hosting Fe-oxide Cu–Au (IOCG) deposits west of the Kiruna mining district, northern Sweden. It is noted that IOCG deposits in different areas worldwide (e.g., Australia, Canada) are preferentially located in proximity to faults associated with deformation zones of regional relevance, and that the deposits are hosted in areas affected by potassic to sodic alteration. This study shows that at a semi-regional scale IOCG deposits occur within areas of high positive gravity anomalies, high values of estimated potassium content and high K/Th ratios, which is an expression of potassic alteration. High magnetic anomalies are associated with magnetite occurrences, while low linear magnetic anomalies mark fault/shear zones, in proximity of which the majority of the IOCG deposits occur.