Magnetostratigraphic reinvestigation of the Palaeocene/Eocene boundary interval in Hole 690B, Maud Rise, Antarctica     

Jason R. Ali  Dennis V. Kent  & Ernie A. Hailwood 《Geophysical Journal International》2000,141(3):639-646

Hole 690B, drilled on Maud Rise near Antarctica, provides one of the most important Palaeocene/Eocene boundary interval sections. Magnetostratigraphy plays a key role in dating Palaeocene/Eocene boundary events, but there are two problems with the published scheme in Hole 690B. The first concerns major mismatches of several magnetozones and biozones in the succession. The second is an unexplained pervasive declination cluster, which should not be present in these azimuthally unoriented piston cores. To resolve these issues, a palaeomagnetic reinvestigation was carried out on 98 specimens from 12 cores through the upper Palaeocene–middle Eocene section in Hole 690B.
The bulk of the samples carry an approximately uniformly directed magnetically hard component resulting in a declination cluster effectively identical to that of the earlier study. The spurious magnetization can be explained either as an 'inward-radial magnetization' or as a 'core-split overprint'. By estimating the extent of the overprint within each sample, it has been possible to construct a filtered magnetostratigraphy for the section. The result is that many of the magnetozone–biozone mismatches are eliminated, and the record of the 2.5 Myr Chron C24r, which brackets the various events associated with the Palaeocene/Eocene boundary, is considerably cleaner. It is not possible to define the upper and lower boundaries of this magnetochron, so we recommend that the dating of the events within this section be based on the biostratigraphy only.  相似文献   

Sequence Stratigraphy Study of the Late Quaternary Activity of the Nankou-Sunhe Fault in Its Northern Segment,Beijing     

Zhang Shimin  Wang Dandan Liu Xudong  Ren Junjie  Luo Minghui  Zhang Guohong  Zhao Guocun  Wang Rui  Zhang Yingli 《中国地震研究》2008,22(3):334-347

A test drilling exploration was implemented across the northern segment of the Nankou-Sunhe fault in the Beijing plain, and a combined borehole section was built by sequence stratigraphy, lithologic facies analysis, magnetic susceptibilityand absolute chronology to investigate the episodic activities of the fault since 60 ka BP. The results show that the active stages of the fault are 60 ka to 47 ka BP, 36 ka to 28 ka BP, and 16 ka BP to present. Other intervals are relatively stable. The average vertical slip rate is 0.35 mm/a from 60 ka to 37 ka BP, 0 mm/a from 37 ka to 3：2 ka BP,0.78 mm/a from 32 ka to 12 ka BP,and 0.35 mm/a since 12 ka BP. Compared with the conventional analyses on lithology and sedimentary facies, the sequence stratigraphy method has certain advantages in the studies of borehole strata comparison and episodic activity of buried faults.  相似文献   

基于多测点分析法的水平井高精度磁方位校正方法          下载免费PDF全文

刘建光  底青云  张文秀 《地球物理学报》2019,62(7):2759-2766

随着水平井、多分支井等技术的出现,随钻测量技术对磁方位精度的要求越来越高.常规单测点磁方位校正法误差较大,无法满足复杂结构对磁方位精度的需求.近年来,国外围绕Brooks多测点分析法的基本公式,建立了一系列优化后的多测点分析法来提高磁方位的精度.本文以多测点分析法的公式为基础,结合常规单测点磁方位校正法,推导出一套收敛的改进多测点分析法.并通过实验来验证改进后的多测点分析法的效果.用改进后的多测点分析法得到的方位角精度在0.2°以内,达到或接近国际先进水平.通过进一步开展数据处理和分析,该套算法可以应用于水平井、多分支井等大斜度钻井工程中的精确定位和导向.  相似文献   

Look-ahead vertical seismic profiling inversion approach for density and compressional wave velocity in Bayesian framework     

Ahmed M. Daoud  Muhammad A. Abd El Dayem 《Geophysical Prospecting》2020,68(3):761-785

To reduce drilling uncertainties, zero-offset vertical seismic profiles can be inverted to quantify acoustic properties ahead of the bit. In this work, we propose an approach to invert vertical seismic profile corridor stacks in Bayesian framework for look-ahead prediction. The implemented approach helps to successfully predict density and compressional wave velocity using prior knowledge from drilled interval. Hence, this information can be used to monitor reservoir depth as well as quantifying high-pressure zones, which enables taking the correct decision during drilling. The inversion algorithm uses Gauss–Newton as an optimization tool, which requires the calculation of the sensitivity matrix of trace samples with respect to model parameters. Gauss–Newton has quadratic rate of convergence, which can speed up the inversion process. Moreover, geo-statistical analysis has been used to efficiently utilize prior information supplied to the inversion process. The algorithm has been tested on synthetic and field cases. For the field case, a zero-offset vertical seismic profile data taken from an offshore well were used as input to the inversion algorithm. Well logs acquired after drilling the prediction section was used to validate the inversion results. The results from the synthetic case applications were encouraging to accurately predict compressional wave velocity and density from just a constant prior model. The field case application shows the strength of our proposed approach in inverting vertical seismic profile data to obtain density and compressional wave velocity ahead of a bit with reasonable accuracy. Unlike the commonly used vertical seismic profile inversion approach for acoustic impedance using simple error to represent the prior covariance matrix, this work shows the importance of inverting for both density and compressional wave velocity using geo-statistical knowledge of density and compressional wave velocity from the drilled section to quantify the prior covariance matrix required during Bayesian inversion.  相似文献   

气举反循环连续取心工艺探索          下载免费PDF全文

殷国乐  王艳丽  陈浩文  王林清  许刘万 《探矿工程》2022,49(2):22-29

气举反循环钻进技术是钻井工程中一种比较成熟的钻进手段,已经得到了广泛应用。但气举反循环连续取心技术仍处在探索研究阶段,前人已经针对这一技术做了原理性探究试验,但尚未进行连续的取心试验,而且现有的双壁钻具也存在无法满足由于上返岩心质量和直径大对其密封性和耐用性的要求。因此有必要进一步开展理论研究、优化钻具设计、进行连续取心试验来探究这一工艺发展前景。通过试验证明大通径双壁钻具设计可靠耐用,成功连续取得岩心。所取岩心及时,无污染,代表性强,能较真实的反映地层层位、深度、颗粒级配,不存在对岩心反复冲刷及重复破碎状况。  相似文献   

剪切波速测试方法的现状分析   总被引：1，自引：0，他引：1       下载免费PDF全文

郭明珠  贾连军  铁瑞  姜倩  胡哲明 《地震工程学报》2011,33(Z1)

目前测试场地土层剪切波速的方法有单孔法、跨孔法、瞬态面波法和稳态面波法,它们适用于各种工况。对各种波速测试方法进行了系统总结,指出其适用范围及优缺点。介绍了随钻地震这种新的原位测试方法,论述了该方法的应用前景。  相似文献   

WFSD地应力台应变特征及其同震效应分析——以日本Mw9.0级特大地震为例     

彭华  马秀敏  姜景捷  彭立国 《地质力学学报》2011,17(1):1-14

2011年3月11日在日本东北部海域发生Mw9.0级强烈地震,汶川地震断裂带科学钻探(WFSD)项目设在陕西汉中地区的体应变仪记录到了完整的应变数据.通过采集数据的分析,探讨了日本Mw9.0级特大地震发生时的同震变化以及地震前后固体潮异常变化过程,分析了地震孕育、发生过程中应变固体潮的趋势性异常及畸变等各种异常现象,并...  相似文献   

哥斯达黎加地震起源计划——IODP334航次介绍     

朱俊江 《地球科学进展》2011,26(12):1300-1305

2011年3月13日至4月13日哥斯达黎加地震起源计划IODP334航次在中美洲哥斯达黎加俯冲带大陆边缘斜坡带实施。该航次的主要科学目标是研究俯冲剥蚀控制的俯冲带大地震的聚集和破裂过程。在1个月的钻探时间内,总共在4个站位、8个钻孔中获得1492．88m的岩芯,获得许多中新世到现代的火山灰层,初步确定上覆板块内沉积物和...  相似文献   

水平定向钻岩石层穿越套管安装工艺     

宋龙进  刘保站 《岩土钻凿工程》2011,(6):9-11

在水平定向钻穿越长距离、复杂地质条件施工中,为保证穿越导向孔钻进工程的顺利进行,避免或减少钻杆在传递推力时在钻孔内产生“蛇行”弯曲、不能有效传递推力、钻进方向不易控制等不利因素,通常采用在钻机侧沿钻进方向的钻杆上加装部分套管技术。本文详细阐述了水平定向钻岩石层穿越套管安装的施工流程、安装技术措施,同时对套管的钻进、润滑、回抽等环节进行了分析,并对套管施工过程中安全注意事项提出了几点建议。  相似文献   

3种钻孔应变仪记录的玛多MS7.4地震同震响应特征对比分析     

樊俊屹  刘高川 《中国地震》2021,37(3):564-573

针对2021年5月22日青海玛多MS7.4地震,采用3种型号的钻孔应变仪观测到的应变资料对比分析同震应变波,结果表明3种仪器记录同震的初动时间、波动幅度和持续时间等存在一定差别:在震中距相当的情况下,TJ型体应变仪和RZB型四分量钻孔应变仪存在波动幅度变化小、持续时间短的问题,难以从背景变化中区分同震响应,影响钻孔仪器同震规律研究; YRY?4型四分量钻孔应变仪波动幅度变化大,持续时间长,在映震效果上表现较为突出。  相似文献