Determination of cave geometry by using a geoelectrical resistivity inverse model

Determination of the geometry and the dimensions of a cave is an important factor considered for planning geotechnical, archeological, speleological studies, and quarrying activities. In recent years, researchers have raised an increasing number of questions related to the shape and size of cavities using 2D geoelectrical resistivity imaging techniques. The inverse model is valuable in detecting the location and extent of subterranean cavities. In this study, a 2D geoelectrical resistivity imaging technique is employed to determine the geometry of a known subterranean cavity. The results provided valuable information and demonstrated the effectiveness of the technique for exploring the size of cavities.     

Paleovalley-related uranium deposits in Australia and China: A review of geological and exploration models and methods

The features and similarities in the geology of paleovalley-related uranium mineralizing systems in Australia and China can be used to refine strategies for exploration. Paleovalley-related uranium resources include sandstone-, lignite- and calcrete-style deposits that are developed within the host sediments deposited in paleovalleys. The paleovalleys incise either crystalline bedrock or older sedimentary rocks, and uranium was deposited and concentrated by the influx of oxidized/reduced groundwaters flowing in aquifers within the paleovalley fill. The critical features of paleovalley-related uranium deposits include sediment and uranium sources, geological setting, depositional environment, age and relative timing of mineralization, aquifer characteristics, availability and distribution of reductants, and preservation potential of the uranium mineral system. This set of information provides a basis to establish the uranium mineralization model, which can then be used to assist with generating targets for uranium exploration and prospectivity analysis of a region. With respect to Sino-Australian examples, paleovalley-related uranium deposits form mostly around the margins of sedimentary basins and the mineralization is commonly hosted within channel fills contained within paleovalleys developed upon, or proximal to, Precambrian crystalline rocks that contain primary uranium sources. The deposits that have been well studied show remarkably similar factors that controlled the formation of paleovalley-related uranium deposits. Basement/bedrocks with above-background (2.8 ppm U) levels of uranium (10–100 ppm) that are linked to, and/or, incised by paleovalleys are associated with these deposits and are the inferred source of the uranium. In these regions, extensive fluvial systems developed particularly during Mesozoic and Cenozoic times, uranium from the bedrock was first dispersed into the sediments, and then concentrated to form deposits through successive chemical remobilization, precipitation and concentration. The deposits formed in continental or marginal marine environments, and commonly are associated with reduced lithologies, containing pyrite and dispersed organic matter and/or seams of lignite, or show evidence of infiltrated hydrocarbons. The mineralization is developed where oxidizing fluids (carrying dissolved U) reacted with reductants in the sediments. Geological, geophysical and geochemical features of the paleovalleys and related uranium deposits are used to construct models to understand host sediment distribution, fluid flow and ore genesis that can assist exploration for paleovalley-hosted uranium deposits. Precise geometric definition of the basin margin and paleovalley architecture is important in identifying exploration targets and improving the effectiveness of drilling. Refinements in remote sensing, geophysical and data processing techniques, in combination with sedimentological and depositional interpretations, provide an efficient approach for outlining the principal drainage patterns and channel dimensions. To help reduce risk, an exploration strategy should combine these technologies with a detailed understanding of the physicochemical parameters controlling uranium mobilization, precipitation and preservation.     

风雨兼程六十载，不忘初心向前行——纪念《探矿工程》杂志创刊60周年历史回顾

《探矿工程》杂志创刊于1957年10月。60年来,曾两度停刊、复刊,几次变更刊名,几易主办单位,在历届编委会和编辑部的努力和坚守下,在广大读者、作者的支持和陪伴下,顽强地走过了风雨兼程的60年。她在书写自己60年辉煌历史的同时,也完成了一部记录中国探矿工程技术发展历史的巨著。当前她正面临着来自学科调整、评价体系、新兴媒体等的冲击以及经济方面的压力。展望未来,将继续坚持注重实用性、理论与实践相结合、学习国外先进经验的办刊宗旨,继续做探矿工程（岩土钻掘工程）技术发展的忠实记录者。     

甘肃省地质勘查基金项目勘查成果综述

甘肃省地质勘查基金设立于2009年,至今共设置勘查项目259个,总经费34.2亿元。勘查项目主要部署在甘肃北山、阿尔金—祁连山、西秦岭及陇东地区等主要成矿区带,勘查矿种主要有能源矿产(煤炭、地热、页岩气、铀)、金属矿产(铁、锰、钒、钛、铜铅锌、钨钼、金银、铌钽)、非金属矿产(萤石、石膏、晶质石墨、硅灰石、水泥灰岩、重晶石、花岗岩饰面石材)。其主要目的是增强矿产资源对甘肃经济社会可持续发展的保障能力,提高政府对矿产资源的调控水平,规范矿业权市场。通过省地矿局、省有色地勘局、省煤田地质局、省核工业地质局等单位的组织实施,煤炭、页岩气、铁、铜、金、晶质石墨等矿种勘查取得了较大的突破。其中,以大会战的方式,相继开展了环县、正宁县南部、宁县中南部等大型煤田勘查,创造了地质找矿的"陇东模式",累计查明煤炭资源量204.6亿吨。为陇东能源基地建设奠定了资源基础。在陇东、武威、敦煌盆地开展了页岩气资源调查评价工作,其中敦煌盆地页岩气调查取得突破性进展。在镜铁山外围卡瓦一带开展的铁矿勘查累计提交铁矿石资源量达5.3亿吨,是甘肃又一处在全国具有宏观影响的铁矿勘查重大成果。白银铜矿深部勘查是老矿山深部探边摸底找矿突破的典型事例,新增铜铅锌金属量51.93万吨,对延长白银铜矿山寿命具有重要意义。金矿勘查也取得了重要进展,累计探求金金属资源量43.07 t。晶质石墨作为新兴战略性矿产,连续找矿突破,初步探求资源量达490万吨。上述勘查成果显示,在矿业市场持续低迷的环境下,省地勘基金对全省地质找矿和矿业开发起到了显著的促进作用,对全省经济社会发展具有重要意义。     

四川盆地中二叠统栖霞组、茅口组岩相古地理及勘探方向

通过地层剥蚀关系分析,四川盆地中二叠统沉积前的古构造格局具有"三隆一洼"的特点。基于野外剖面、岩心和薄片观察,结合录井、测井相和地震相分析,明确了栖霞组和茅口组发育镶边碳酸盐岩台地沉积,包含一级台缘带、二级台缘带、开阔台地和台盆等4种亚相以及一级台缘滩、二级台缘滩、台内滩和硅质台盆等微相。栖霞组、茅口组岩相古地理受控于沉积前古构造:一级台缘带分布于古隆起与斜坡—盆地过渡地带;开阔台地分布于古隆起区和低隆起区;台盆分布于低洼区;二级台缘带分布于开阔台地和台盆之间的过渡地带。类比上二叠统长兴组和下三叠统飞仙关组油气勘探,栖霞组、茅口组台地内部的二级台缘带可作为下一步油气勘探的有利领域。     

生物地球物理:地球物理方法在研究生物地球化学过程中的应用和发展

微生物广泛参与了其所处地质环境的物理和化学性质改造过程.监控微生物与地质介质之间相互作用的过程并了解其机制对近地面环境工程中土壤及地下水污染整治等实际应用有着至关重要的作用.地球物理勘测成像技术不仅能够在传统应用中测量和表征地表以下的物理特性变化,大量直接有效的证据表明这些方法还可以捕获孔隙介质中的生物地球化学变化的动态过程,包括监测微生物、微生物活动以及它们与矿物之间的相互作用.生物地球物理(Biogeophysics)作为勘探地球物理的一个新兴分支学科,包含了微生物学、生物地球科学以及地球物理勘测等多个学科,侧重于研究微生物与地质介质相互作用对地球物理场的影响.过去十几年在生物地球物理领域的研究充分表明和验证了地球物理勘测方法的独特优点(最小化侵入、时空连续及跨尺度运用),并为将传统勘测方法用于探索跨时间空间各尺度的地下生物地球化学动态过程提供了理论及实验依据.本篇综述将系统介绍生物地球物理学科的理论背景、发展和研究前沿.首先讨论微生物及其活动引起的孔隙介质中物理化学性质的变化.其次,将侧重于探讨微生物活动对包括地电法、电磁法、探地雷达以及地震法等不同地球物理场的响应.最后将讨论生物地球物理领域的机遇、挑战和潜在应用.     

基于因子分析和季节趋势滤波方法的地球物理因子识别以唐山台跨断层数据为例

利用因子分析可以有效地找出多个变量的公共因子, 找出隐含因素; 基于季节趋势滤波方法, 可以分析序列的周期成分和趋势变化特征, 结合区域地震特征, 确定序列的物理意义。 本文将这两种方法结合, 提出了完整的地球物理因子识别方法, 并将其应用于唐山地震台跨断层形变短基线序列, 获得了具有物理意义的三个公共因子, 即远场构造因子、 台站因子和近场构造因子。     

Improvements on particle swarm optimization algorithm for velocity calibration in microseismic monitoring

In this paper,we apply particle swarm optimization(PSO),an artificial intelligence technique,to velocity calibration in microseismic monitoring.We ran simulations with four 1-D layered velocity models and three different initial model ranges.The results using the basic PSO algorithm were reliable and accurate for simple models,but unsuccessful for complex models.We propose the staged shrinkage strategy(SSS) for the PSO algorithm.The SSS-PSO algorithm produced robust inversion results and had a fast convergence rate.We investigated the effects of PSO's velocity clamping factor in terms of the algorithm reliability and computational efficiency.The velocity clamping factor had little impact on the reliability and efficiency of basic PSO,whereas it had a large effect on the efficiency of SSS-PSO.Reassuringly,SSS-PSO exhibits marginal reliability fluctuations,which suggests that it can be confidently implemented.     

低渗透油气资源勘探开发技术进展

通过对国内外低渗透油气资源的分类、资源量、分布状况、勘探开发技术研究现状的分析,指出低渗透油气层的识别和改造技术、钻采工艺技术是当前国际低渗透油气勘探开发技术研究的热点。当前和未来国际低渗透油气资源研究将主要关注:低渗透储集层优质储集体预测技术、压裂技术、水平井和多分支井技术、小井眼钻井技术、超前注水技术、层内爆炸增产技术、微生物采油技术等技术领域。我国今后需要进一步发展超深井钻井、沙漠山地等复杂地表条件高分辨率地震勘探和解释技术、复杂岩性油气层测井技术、低渗透含油区带优选技术、低渗透储层微观孔隙结构研究技术、低渗透储层裂缝先期预测技术、开发压裂优化注采系统技术、水平井、复杂结构井压裂技术、低渗透油藏注气提高原油采收率技术、小井眼钻井技术等。     

小口径绳索取芯法与普通钻进取芯法比较

绳索取芯钻进技术改变传统的提钻取芯过程,降低劳动强度,大幅度提高时间利用率、钻探效率及取芯质量。目前,绳索取芯钻进方法已经广泛应用于地质勘探、工程勘察和水文工程地质等多种要求采取岩芯的钻进工程中。本文结合云南某矿区勘察工程钻孔实例,通过小口径绳索取芯钻进工艺与普通取芯钻进工艺对比来说明其先进、高效的特点。