Application of high density resistivity method in accuracy of goaf detection

Based on the relationship between the diameter and buried depth of goaf,the authors establish the forward modeling by Res2dmod and inverse the model by Res2dinv. Thus,three kinds of models are obtained:the model of single resistivity anomalous body,model of double different distance resistivity anomalous body,and model of layered resistivity anomalous body. Using forward and inversion,the image of detection is simulated,and the reliability is proved by comparing with the engineering examples.     

基于聚类算法的钻孔瞬变电磁视电阻率立体成像方法

煤矿井下地球物理水害超前探测要求探测点20 m范围内不得有积水和金属物体,传统电磁法超前探测技术已不能满足要求,钻孔瞬变电磁法通过将收发装置送入掘进工作面前方的钻孔中进行探测,既远离了巷道中的各种干扰,又提高了隐蔽致灾水体的探测精度。为解决该方法对钻孔径向异常体的准确定位解释难题,通过三维正演总结了其水平分量异常响应特征,提出了异常体象限确定准则,研究了根据水平分量幅值和异常象限综合求取异常体工具面角的计算方法。将由垂直分量计算得到的每一个视电阻率视为独立异常体,基于K-means聚类算法对相应的水平分量异常曲线特征值进行二分类,实现了全数据集的视电阻率象限自动划分,结合异常工具面角算法研究得出钻孔瞬变电磁视电阻率立体成像方法。最后计算了三维数值模型的立体成像结果,对钻孔径向的小规模低阻异常体取得了良好效果。结果表明:基于K-means聚类算法的钻孔瞬变电磁视电阻率立体成像方法是地球物理与机器学习的有机结合,该方法能够为井下掘进工作面隐伏水害超前探测精细解释提供技术支撑。     

三维电阻率概率成像法研究

电阻率概率成像法是利用地表电场的测量值与电场扫描函数进行归一化的相似程度作为概率的成像方法。根据概率论的基本理论,引入幂函数并推导了电阻率异常发生概率函数。通过数值模型实验对此方法进行了验证,对多个孤立异常体和凹陷模型进行了概率成像。通过对浙江某地实测资料概率成像结果与常规最小二乘法反演结果进行比较表明,三维电阻率概率成像法能较好地分辨地下地电结构。     

高密度电法反演软件在邹平章丘火山岩区铜矿勘查激电测深反演中的应用

在山东省邹平-章丘火山岩区铜矿勘查工作中,为了克服地形因素引起的假异常,使勘查成果接近实际地质情况,应用高密度电法反演软件RES2DINV软件进行了带地形的激电测深资料反演,结合地质资料及激电中梯资料,推断了低阻高极化异常体,经钻探验证异常体为铜矿体引起。在地形复杂地区开展激电工作,可以应用此方法,减小预布验证钻孔难度。     

Subsurface sandstone mapping by combination of GPR and ERT method

It is important to know the shape and distribution of sandstone bodies in the subsurface when forma-tion and migration of a dune model are determined.The information plays a significant role in identification of the continental oil and gas accumulation.In this study,the combination of ground penetrating radar (GPR) and electrical resistivity tomography method (ERT)is used in mapping the distribution of sandstone bodies in Yanchang Formation.Six GPR profiles and seven ERT profiles are used to analysis.GPR data show clear re-flections from the top interface of sandstones.ERT data show a continuous high resistivity anomaly correspon-ding to the sandstone body.Combined the reconstructed 3D images by GPR and ERT,the spatial distribution of sandstone bodies is described.     

首都圈地区数字化钻孔应变观测资料分析

结合地震活动性、气压及钻孔体应变观测资料,对首都圈地震活动与应变场变化关系进行了研究。结果表明:首都圈地震活动与测区钻孔体应变信息合成值的异常变化具有密切关系;地震活跃时间与体应变变化的时间同步;地震活跃区与体应变增强性异常变化分布区域一致。     

复杂二维地电断面电测深法的反演研究

本文在二维地电断面直流电测深法的边界单元法正演的基础上,将可行方向法引入LMF算法中,提出了改进的阻尼最小二乘可行方向法的二维电测深反演方法。同时,为了克服反演参数多、反演时间长的困难,本文使用了对反演参数进行抽样反演的方法,大大减少了反演参数。然后,采用拉格朗日插值法求出反演界面。最后,将以上方法用于二维起伏基底的电测深资料反演中。     

随钻核磁共振测井在南海文昌油田低阻油层流体识别中的应用

随钻核磁共振测井在南海文昌油田低阻油层的开发中以安全高效的测井方式提供了孔隙度、渗透率等参数,且在定性识别轻质油层方面发挥了关键作用。为了进一步提升随钻核磁共振测井在文昌油田低阻油层流体识别中的使用价值,从孔隙结构和流体性质2个影响因素出发,提出了T₂谱含油特征指标法并引入纯水谱重构法开展流体定量识别。其中T₂谱含油特征指标法以消除孔隙结构的影响为基础,利用轻质油和水的横向弛豫时间差异提取轻质油真实的拖尾现象达到定量识别流体的目的;水谱重构法则采用球管模型和正态分布模型分别构建束缚水谱和可动水谱,并将两者之和作为纯水谱,通过与实测核磁T₂谱的对比提取流体性质信息,达到识别流体性质的目的,2种方法在文昌油田低阻油层的流体识别中均取得了良好的应用效果,可在低阻油层、水淹层等储层流体的定量识别中发挥显著作用。     

跨孔视电阻率异常特征的提取和识别

讨论了奇异值向量作为二维数字图象特征的理论依据并用于跨孔条件下视电阻率异常信息剖面图。对位于钻孔剖面内的三维椭球体模型,利用系统正演结果所建立的样本集,进行了视电阻率异常信息剖面图的奇异值特征提取和识别,取得了满意的初步结果。     

基于序列二次规划方法的高密度电阻率反演

针对高密度电阻率成像法反演计算中存在的困难，探讨了基于序列二次规划（SQP）方法建立可行的电阻率反演算法的问题。在对三维点电源二维地电体电位场模型有限元法正演计算的基础上．建立了基于SQP方法的高密度电阻率成像法反演算法。根据勘测中测量电极间距的不同，提出按不同的电极间距分别建立优化模型进行参数优化。通过对模拟电阻率模型和实际观测资料的反演计算．表明该算法进行高密度电阻率反演是可行的，其具有对初始模型无特殊要求、收敛速度快的特点。这一反演算法可望在高密度电阻率成像的反演计算中得到应用。     

Investigation on influence factors of dual laterologs curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form of dual laterologs, forward modeling technique were applied to calculate the dual laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than lm, the two-peak on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m, the form of logs does not vary significantly. If the formation thickness is greater than 4 m, a platform appears on the logs at the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tend to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between invaded zone, uninvaded formation and adjacentlayers.     

Investigation on influence factors of dual laterologs curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form of dual laterologs, forward modeling technique were applied to calculate the dual laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than 1m, the two-peak on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m, the form of logs does not vary significantly. If the formation thickness is greater than 4 m, a platform appears on the logs at the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tend to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between invaded zone, uninvaded formation and adjacentlayers.     

地震地电阻率交流观测方法及观测实验

介绍地震地电阻率交流观测的原理及方法、观测系统的要求及主要技术指标,并在受地铁干扰严重的江宁台进行实验观测。初步观测结果表明,该系统观测结果与直流观测结果相当,能满足台站实际观测需求,同时达到抗干扰目的。证明采用交流供电方法进行地电阻率观测,能够在较强干扰背景下获取较高的信噪比,很好地抑制城市地铁、轻轨以及其他因素引起的电磁干扰。
     

新疆精河莱历斯高尔铜钼矿床原生地球化学异常

矿区处于博罗霍洛山主脊,属斑岩型铜钼矿床。斑岩体本身为矿体,钼矿在岩体内,铜矿在外接触带。通过矿区北部勘查地球化学工作表明,Mo、Cu、Pb、Ag、As原生地球化学异常规模大、连续性好,形态规则,梯度大。As、Sb、Ag具前缘特征。除Mo、Cu外,Pb、Ag具主成矿元素特征。原生异常纵向分带具轴向分带特征,分带序列有一定的典型意义。从地质、地球化学异常特征、小岩体地球化学特征以及金属预测资源初步计算认为该矿床很有远景。     

扩边尺度对重力异常分层分离处理的影响——以插值切割法为例

以插值切割法为例,对理想模型在地表的重力异常数据进行不同尺度的扩边,并对扩边后的数据进行不同深度层源的切割分离。基于分离后的结果,从不同扩边尺度、不同深度层源的重力异常差异、扩边尺度与重力场源分离误差的角度研究扩边尺度对重力异常分层分离处理的影响。结果表明： 1） 理想模型数据区域的边界效应与扩边尺度、切割分离深度、异常的规模和幅度及空间位置等因素相关; 2） 扩边尺度的选择应综合考虑分析资料所需满足的精度和数据计算效率,扩边尺度不宜过大,扩边尺度与重力异常分层分离最大切割深度至少应满足2∶1的要求才能明显改善边界效应,对含有较大重力异常边界进行切割分离时,应在2倍扩边尺度的基础上再进一步扩边; 3） 边界效应的空间展布不是由数据区域边界向中心区域均匀分布,而与异常体的规模和空间位置有关。     

False anomaly recognition with horizontal differential field lines method in high-density electrical technique and its application in Xinlei Quarry,Jiuquan

As an important geophysical tool,high density electrical technique infers the underground geological structures by processing and inverting the apparent resistivity data.Currently,the false anomalies have been frequently occurred in the graph of apparent resistivity pseudo-section or inverted geoelectrical section obtained from high-density electrical technique,and are difficult to remove.In this study,the authors explain the mechanism of the false anomalies and put forward the horizontal differential field method to identify the false anomalies.Based on the analysis of modeling results,this method is applied in the surveying data in Xinlei Quarry of Jiuquan,and the results confirm the effectiveness of the horizontal differential field method.     

同时检测监测网的异常形变和粗差

粗差干扰影响形变分析成果的质量，以往都是粗差与异常变形分开来检测，即对每一期观测锡除粗差后再进行平差，然后利用两期或多期平差结果进行形变分析，这两步是重复的，为此，从位移观测方程入手，根据粗差检测与异常形变检测相似的特点，提出将粗差与异常形变同时检测，根据二者的不同特点，将它们区分开的新思路。通过算例分析比较了拟准检定法、假设检验法及相关抗差估计方案的检测效果，结果表明拟准检定法具有比其它两种方法实施简单、定位准确的优点，同时验证了这种思路的可行性。     

五极纵轴测深法在龙岩灰岩地区寻找岩溶水的应用

曲潭测区内地形较平坦,多为第四系覆盖,表层土质较均匀,接地条件较好,选择五极纵轴电测深法在区内寻找岩溶地下水,通过视电阻率及激电二次场的测量,对物探异常的解译和深部钻孔验证,成功找到日出水量达千吨以上的岩溶地下水,为今后在灰岩地区寻找岩溶地下水提供借鉴意义。采用物探方法寻找岩溶地下水是一种不可替代的勘查方法,可以减少单纯钻探成井的盲目性,提高找水的成功率。     

Joint inversion of magnetotelluric and fullwaveform seismic data based on alternating cross-gradient structural constraints

Magnetotelluric(MT)inversion and seismic inversion are important methods for the interpretation of subsurface exploration data,but separate inversion of MT and seismic produces ambiguous and non-unique results due to various factors.In order to achieve accurate results,the authors propose a joint inversion method of two-dimensional MT and seismic data in the frequency domain.The finite element method is used for numerical simulation of electromagnetic data in the forward modelling,and the Gauss-Newton method is used for the inversion.The 9-point-finite-difference method is used to solve the seismic wave field in the acoustic wave equation,and the inverse problem of seismic data is solved by full waveform inversion with a conjugate gradient,a simple and fast method.Cross gradient functions are used to provide constraint structure between resistivity and velocity parameters to carry out the joint inversion.The joint inversion algorithm is tested by double-rectangular model synthesis data,and the accuracy of the algorithm is verified.The results show that the joint inversion results are better than those from separate inversion.The algorithm is applied to a geophysical model of a metalliferous deposit in Jinchuan and is compared with the separate inversion results.It shows that the results obtained with joint inversion are much closer to the real model.     

3 D inversion of borehole gravity data using cokriging

Borehole gravity has been used in mineral exPloration recently with the advent of slim-hole gravime-ters. It is logical to Perform inversion to utilize the information in the newly acquired data. The i...