The match game: New stratigraphic correlation algorithms

New algorithms for automatic correlation of geologic strata are introduced. The algorithms are extensions of the Smith and Waterman (1980) dynamic programming technique and include several features that greatly increase the utility for sedimentary sequences. Gaps in correlation (unconformities) caused by local nondeposition or eroded strata can include in a single event several strata. Furthermore, these gaps can be weighted as a single event, rather than as the sum of gap events for each strata. In addition, one or several adjacent strata in a second column can be correlated (matched) with one or several strata in a second column. Deletions within one of these multiple matches are also possible. The new algorithms include the method of minimum distance and the method of maximum similarity. Within this context, a similarity algorithm is given to locate and correlate the best matching segments or intervals from each stratigraphic column. All correlations within a preset distance of the optimum likewise can be produced for any of these algorithms. An example of specific assignments of these weight functions is given for correlation of well logs from the San Juan Basin.     

主分量分析法在测井解释工作中的应用

主分量分析法(PCA)的数学原理是坐标转换,它将原变量变换成互不相关的变量。在实际应用中,它为综合解释法提供了一种变量组合的途径。从物理意义上来说,它可以求出各物理参数的权系数,从而判断出,在各个主分量中各个参数的贡献大小。这样,我们便可以有目的地选择各参数,利用主分量PCA曲线进行地质解释。本文概述了主分量分析法PCA的基本原理和自编的分析程序流程,并以新疆塔北地区为例,说明了分层、计算泥质含量及孔隙度的成果。应用实例表明,在测并解释工作中应用主分量PCA曲线可以取得更准确、更细致的效果。具体地说,在新疆塔北地区砂泥岩薄互层组上,可以用主分量PCA曲线进行薄互层组的地质解释。     

Study on the Electrical Conductivity of 0.025 mol NaCl Solution at 0.25-3.75 GPa and 20-370℃

The electrical conductance of 0.025 mol NaCl solution was measured at0.25-3.75 GPa and 20-370℃. As shown by the results, the conductance increases with temper-ature, and there is a liner relation between the reciprocal of temperature and the logarithm ofthe conductance but their slopes are different at different pressures. The relations between theconductance and pressure is rather complex and there are some discontinuities: in the range of2.25-3.75 GPa, the conductance increases with the pressure; in the range of 1.25-2.0 GPa, theconductance is not related to the pressure; and at a pressure of 0.75 GPa, the conductance ishigher than that at the pressures nearby. This reflects that the NaCl solution has rather differentproperties of electronic chemistry at various pressures, and probably is an important cause forthe existence of the layers with high electrical conductance and low velocity in the Earth's crustand mantle.     

横向中梯电阻率法在充水破碎带调查中的应用

本文应用横向中梯电阻率法，查明了厦门美景花园工地地下破碎带的位置。与实际钻孔资料的对比表明，在工程地基勘察中，利用某些特殊的物探手段，能经济、有效地解决某些工程地质问题。     

The effect of pressure on the electrical conductivity of KTB rocks

Complex electrical resistivity and permeability were measured on two gneiss samples and nine amphibolites (originally located at a depth of 4150 m to 5012 m) from the main drilling of the German deep drilling project (KTB). Measurements were performed as a function of hydrostatic pressures up to 240 MPa on core samples (30 mm in diameter and 10–20 mm high). For each measurement, two samples were used, one being parallel, and one perpendicular to the borehole axis. At low pressures and again at maximum pressure the frequency dispersion (1 kHz up to 1 MHz) of the complex resistivity was measured using a two electrode device. An unusual pressure effect was detected on some of the samples and was established to be due to the oriented deposition of good conducting phases in the foliation. Rock fabric and the orientation of ore mineralization was measured on thin sections and polished sections prepared from the same samples.     

大功率电法在金属矿勘查中的应用效果

介绍大功率电法在东蒙一个矿区的应用实例，通过大功率电法面积工作确定成矿地质环境，结合电测深利用金属因素确定成体的赋存部位，取得较好的效果。     

直流电测深法在寻找地下岩溶水中的应用

本文以南昆线师宗火车站供水水源工点为例,介绍电测深法找岩溶水时,野外工作方法、资料解释和孔位确定方法.     

Subspace inversion of electromagnetic data: application to mid-ocean-ridge exploration

Controlled-source electromagnetic (CSEM) surveys have the ability to provide tomo-graphic images of electrical conductivity within the Earth. the interpretation of such data sets has long been hampered by inadequate modelling and inversion techniques. In this paper, a subspace inversion technique is described that allows electric dipole-dipole data to be inverted for a 2-D electrical conductivity model more efficiently than with existing techniques. the subspace technique is validated by comparison with conventional inversion methods and by inverting data collected over the East Pacific Rise in 1989. A model study indicates that, with adequate data, a variety of possible mid-ocean-ridge conductivity models could be distinguished on the basis of a CSEM survey.     

苏通大桥地基中深厚软土电阻率试验研究

通过室内电阻率试验和土工试验,对长江下游苏州-南通长江公路大桥地基中深厚软土电阻率特征及其与物理力学参数的相关关系问题进行了研究。发现,（1）在同一钻孔（即CZK30）中,从粉质黏土→粉砂→细砂→中粗砂,土样的电阻率逐渐增大。电阻率随含水率、孔隙比、饱和度的增加而减小,而随垂直渗透系数、水平渗透系数、压缩模量、标贯等的增加而增大。（2）CZK30孔中粉质黏土电阻率随含水率、孔隙比、饱和度、压缩系数、液限系数增加而减小,而随压缩模量、黏聚力等的增加而增大。（3）通过拟合,提供了软土电阻率与物理力学参数相关关系的量化表达式,拟合曲线与试验数据点的相关程度较高,相关系数绝大部分在0.88以上。结果表明,土电阻率与其它物理力学参数间存在密切的联系。