黄土磁化率的古气候意义对研究红土磁化率古气候意义的启示

中国黄土是蕴含古气候信息最为丰富的晚新生代陆相沉积物,也是连续记录第四纪乃至中新世以来亚洲内陆气候演化的物质载体.20世纪80年代学界首次发现黄土-古土壤磁化率可以作为东亚夏季风强弱的代用指标之后,磁化率作为一种能简单、快捷反演古气候的代用指标,在全球很多黄土剖面不断得到证实,被广泛用于海陆气候对比和古气候重建.自此之后,有学者尝试将磁化率反演古气候的应用范围扩大到中国南方红土.然而目前能否将磁化率作为反演古气候的代用指标完全适用于中国南方红土依然存在很大分歧.显然要准确理解红土磁化率是否具有明确的古气候意义,需要首先研究黄土-古土壤磁化率之所以能作为古气候代用指标的物理化学机制是什么,以及红土沉积物是否和黄土一样具有相似的磁性矿物形成机理.因此本文以分析黄土-古土壤磁性增强的原因为逻辑基础,以总结黄土-古土壤磁性矿物的种类和粒度特征为研究切入点,讨论黄土-古土壤磁化率具有古气候意义的原因.在此基础上分析红土磁化率是否具有明确的古气候意义,亦即进一步研究黄土-古土壤的磁气候学理论是否完全适用于中国南方红土.     

陕西交道全新全黄土—黑垆土磁化率的CBD研究

根据黄土高原中部交道剖面全新世黄土－黑垆土剖面的非磁滞磁化率和ＣＢＤ提取前后的磁化率,频率磁化率以及热磁分析结果,分析了磁性太物的种类和磁畴状态,讨论了古土壤的磁化率增强,指出ＣＢＤ技术强有力的支持古土壤磁化率增强的土壤成因观点。虽然ＣＢＤ能非常有效地溶解土壤成因的磁赤铁矿,但并不是守全选择性的深解土壤成因的磁铁矿颗粒。此外,通过对样品ＣＢＤ处理前后磁化率数据的分析,从土壤化学角度为黄土的风成说提     

矫顽力组分定量分析揭示下蜀黄土磁化率异常降低的原因

镇江大港下蜀黄土剖面多个层位的磁化率出现异常降低,导致与北方黄土的磁化率记录难以对比.为探讨磁化率异常降低的原因,我们在大港钻探ZK孔获取了岩芯.在10个具代表性的层位采样并测量了其等温剩磁获得曲线.通过基于期望最大化算法的计算程序（Irmunmix V2.2）,定量分析了样品的磁性矫顽力组分（magnetic coercivity component）.结果显示这10个样品可大致分成3类,第一类不含中磁组分,第二类含有较少的中磁组分,第三类则含较多的中磁组分.矫顽力组分的含量与样品中铁锰结核的含量密切相关.铁锰结核含量高的样品,中磁组分、硬磁组分含量也高,而软磁组分含量低,与此对应的是这类样品的磁化率低.表明在铁锰结核的形成过程中,原始的软磁组分被溶解,而产生新的中磁组分、硬磁组分,这个次生变化过程导致样品磁化率异常降低.铁锰结核含量高的样品,经历过较强的还原作用,因此ZK剖面磁化率异常降低是还原作用的结果,可能是某时期降水量增大所致.     

巴基斯坦Bahawalpur黄土岩石磁学特征及磁化率变化机制研究

风成黄土是陆地上分布最广泛的沉积物之一,记载了各种古气候演化信息.目前巴基斯坦的黄土研究甚少,磁化率与气候对应的变化机制研究尚未开展.本文对位于巴基斯坦印度河平原Bahawalpur地区新发现的黄土-古土壤剖面进行系统的岩石磁学研究,结合粒度和漫反射光谱(DRS)数据,讨论巴基斯坦黄土的磁化率变化机制.实验结果显示：Bahawalpur (BH)剖面黄土层主要的载磁矿物为磁铁矿,同时含有少量磁赤铁矿和针铁矿,磁性颗粒以原生的MD和PSD颗粒为主.相对于黄土层,古土壤层则是以针铁矿为主,含有顺磁性矿物和少量磁铁矿.BH剖面磁化率与成土作用关系和中国黄土高原典型剖面相反,磁化率的变化可能存在一个阈值12.8×10^-8m³·kg^-1,在阈值之上,强磁性矿物(磁铁矿、磁赤铁矿)占主导;阈值之下,以弱磁性矿物(主要是针铁矿)为主,这种磁性矿物的转变可能导致磁化率降低.本文可为今后利用磁化率解读该地区地层蕴含的古气候信息提供新线索.

     

陕西交道全新世黄土-黑垆土磁化率的CBD研究

根据黄士高原中部交道剖面全新世黄土－黑垆土剖面的非磁滞磁化率和ＣＢＤ提取前后的磁化率、频率磁化率以及热磁分析结果,分析了磁性矿物的种类和磁畴状态,讨论了古土壤的磁化率增强,指出ＣＢＤ技术强有力的支持古土壤磁化率增强的土壤成因观点．虽然ＣＢＤ能非常有效地溶解土壤成因的磁赤铁矿,但并不是完全选择性地溶解土壤成因的磁铁矿颗粒．此外,通过对样品ＣＢＤ处理前后磁化率数据的分析,从土壤化学角度为黄土的风成说提供了新证据。     

陕西交道全新世黄土-黑垆土磁化率的CBD研究

根据黄士高原中部交道剖面全新世黄土－黑垆土剖面的非磁滞磁化率和ＣＢＤ提取前后的磁化率、频率磁化率以及热磁分析结果,分析了磁性矿物的种类和磁畴状态,讨论了古土壤的磁化率增强,指出ＣＢＤ技术强有力的支持古土壤磁化率增强的土壤成因观点．虽然ＣＢＤ能非常有效地溶解土壤成因的磁赤铁矿,但并不是完全选择性地溶解土壤成因的磁铁矿颗粒．此外,通过对样品ＣＢＤ处理前后磁化率数据的分析,从土壤化学角度为黄土的风成说提供了新证据。     

综合测井资料在研究油气藏沉积相中的应用--以川口油田长六油层组为例

利用测井资料来评价或解释沉积相的方法称为测井相分析．测井资料与沉积学结合形成的测井相分析在研究油气藏沉积相和圈定砂体方面发挥着重要作用．利用综合测井资料物性曲线的形状、幅度、数值大小,建立不同沉积相与测井曲线之间的函数对应关系,分析不同沉积相的测井曲线特征,并对不同沉积相的岩性所对应的测井曲线形态分别进行描述．从单井分析剖面对比区域研究三个层次研究油气藏沉积相,勾画出主砂体的形态和展布方向,在此基础上,讨论了川口油气藏长6油层组油气藏与沉积相之间的关系,研究认为河道沉积是该区油田勘探和开发的首选区带．     

Two pedogenic models for paleoclimatic records of magnetic susceptibility from Chinese and Siberian loess

The magnetic susceptibility (MS) of Chinese loess showing a general proportional relationship to pedogenic grade has been widely recognized and used for reconstruction of paleoclimate by Quaternary scientists. The in-situ pedogenic enhancement of ferrimagnetic content is normally believed to be the main reason for the increase of susceptibility in soil units. However, this pattern of high magnetic susceptibility in palaeosols, and low values in loess, are not replicated in some loess deposits. Siberian loess deposits display a completely opposite susceptibility behavior: high values in loess and low values in palaeosols. This inverse relationship has been explained by the idea that magnetic susceptibility is reflecting the magnitude of an aeolian ferrimagnetic component of consistent mineralogy, the grain size of which is related to average wind velocity. Our magnetic study of Siberian samples in this paper suggests that there are notable differences in magnetic properties between Siberian loess and developed palaeosols, not only in magnetic grain-size and concentration but also in magnetic mineralogy. This evidence is difficult to explain fully through variation in wind strength alone, but implies that the low magnetic susceptibility values in the Siberian paleosol units are a reflection, at least in part, of the alteration of the ferrimagnetic content by post-depositional processes. The Loess Plateau is a very arid area where potential evaporation is always higher than precipitation; pedogenesis occurs under dry oxidising conditions. The Siberian Kurtak region is located on the edge of the tundra where it is always wet and saturation during interglacials will lead to a reducing pedogenic environment. Ferrimagnetic minerals under this condition will be destroyed, resulting in lower magnetic susceptibility. Therefore, great care should be taken when using susceptibility values for paleoclimatic reconstruction.     

中低渗油藏剩余油饱和度监测技术系列优化与应用

套管井剩余油饱和度监测技术是研究剩余油分布最重要的测井方法.针对研究区块中-低孔隙度、中-低渗透率、高矿化度地层水的油藏特点与饱和度监测的现状,对比研究了现有监测技术与仪器装备的性能指标,同时考虑脉冲中子、非弹性散射与地层中元素的相互作用的特性,提出了适用于这种不同油藏地质特点的剩余油饱和度监测系列优化方案.针对某区块编制了整体监测方案,并且对监测资料进行精细处理与解释.多口井实施和应用表明,该方案与应用效果良好.     

深层油气地球物理勘探基础研究

本文讨论当前我国深层油气地震勘探面临的难题及基础研究的三个主攻方向,包括：困难地区深层地震反射体准确成像,地震波场信息学、油气田直接预测的地球物理方法技术等.     

重论"上生下储"与"侧向运移"

油气运移是油气藏形成与分布研究的基础．随着生油层理论的建立和发展,油气“上生下储”与“侧向运移”已经成为解释生油层与储集层关系的金科玉律．随着世界范围内油气勘探实践的积累和油气形成与分布研究,特别是对基岩油气藏勘探研究的不断深入,上述运移途径需要重新加以认识。     

Characteristics and genesis of maghemite in Chinese loess and paleosols: Mechanism for magnetic susceptibility enhancement in paleosols

Morphological characteristics and microstructures of magnetic minerals extracted from Chinese loess and paleosols were investigated using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Our results indicate that maghemite in loess–paleosol sequences was transformed from magnetite through oxidation of magnetite. Maghemite transformed from eolian magnetite during chemical weathering has low-angle grain boundaries among maghemite nano-crystals. Some nano-crystalline maghemites with nanoporous texture resulted from microbe-induced precipitation of magnetite or transformation of poorly crystalline ferric Fe (oxy)hydroxides in presence of Fe-reducing bacteria. Aggregates of euhedral maghemite nano-crystals were transformed from magnetite magnetosomes. Both microbe-induced nanoporous magnetite and microbe-produced magnetite magnetosomes are directly related to microbial activities and pedogenesis of the paleosols. It is proposed that the formation of nano-crystalline maghemite with superparamagnetic property in paleosol results in the enhancement of magnetic susceptibility, although the total amount (weight percent) of magnetic minerals in both paleosol and loess units is similar. Our results also show that nano-crystalline and nanoporous magnetite grains prefer to transform into maghemite in semi-arid soil environments instead of hematite, although hematite is a thermodynamically stable phase. This result also indicates that a decrease in crystal size will increase stability of maghemite. It is also inferred that surface energy of maghemite is lower than that of hematite.     

油气井永久性光纤Bragg光栅传感监测系统安装设计

油气井永久性光纤Bragg光栅传感监测系统的安装设计是现场应用的一个重要组成部分,也是工艺最复杂、成本最昂贵的一个环节.本文简要地回顾了油气井光纤Bragg光栅传感监测系统安装现状,根据国内常用射孔完井方式,设计了两种单井光纤Bragg光栅井下安装模型.论述了井下安装前准备工作和主要注意事项,讨论了存在问题,对油气井永久性光纤Bragg光栅传感监测技术及其安装技术的前景进行了展望.     

光纤Bragg光栅在油气工业中的若干应用及进展

简要介绍光纤Bragg光栅的基本原理、传感检测系统的构成,以及利用光纤Bragg光栅进行温度、应变同时测量区分技术.光纤光栅作为新一代传感元器件,越来越受到广大油气工业用户的青睐.本文主要讨论光纤Bragg光栅在油气工业中的若干应用,并对存在问题和应用前景进行了展望.     

Accumulation characteristics and the main controlling factors of Lunnan multilayer oil province,Tarim Basin,China

Lunnan region is a large-scale paleohigh with many coexisting oil and gas bearing series.At present, about 2 billions tons of proved,probable and possible oil and gas reverses have been proved there.Eight oil and gas bearing series have been found in the Ordovician,Carboniferous,Triassic and Jurassic of Lunnan region,they all bear the characteristics of large-scale multilayer oil-gas province.Ordovician is the main reservoir series where over 0.8 billion tons of oil geologic reserves were discovered,and a super large-scale marine carbonate oil and gas field has formed.Reservoir space of the carbonate reservoirs is mainly composed of dissolved hole,dissolved pore and fracture in Lunnan paleo-burial hill.Generally, dissolved holes are widely distributed among them.Reservoir developments are mainly controlled by karstification and tectonic disruption.Due to the similar geochemical characters,the Ordovician,Carboniferous,Triassic and Jurassic oil and gas reservoirs present the same oil source rock of Mid-Upper Ordovician,the latter except Ordovician are mostly of secondary oil and gas reservoirs migrated vertically by faults during the process of multiple phase tectonic movement,adjustment and reconstruction. Lunnan composite oil and gas accumulation region is situated in the vicinity of large-scale hydrocarbon generation depressions in three directions,ample oil and gas from hydrocarbon generation depressions supplied the adjacent oil and gas reservoirs once.Hereby,the succeed paleohigh is the long-term hydrocarbon accumulation region,which is favor for the formations of high quality reservoirs,fault systems and huge-scale composite oil and gas accumulation.