Approximately-Balanced Drilling in Daqing Oilfield

The Daqing oilfield is a multilayered heterogeneous oil field where the pressure are different in the same vertical profile causing many troubles to the adjustment well drillings. The approximatelybalanced drilling technique has been developed and proved to be efficient and successful in Daqing oilfield. This paper discusses the application of approximately-balanced drilling technique under the condition of multilayered pressure in Daqing oilfield, including the prediction of fornmtion pressure, the pressure discharge technique for the drilling well and the control of the density of drilling fluid.     

层状地基持力层承载力的确定

通过对层状地基的分析 ,提出了对层状地基持力层承载力进行修正的方法 ,并通过对同一住宅小区已沉降稳定的 2栋楼采用的承载力及使用情况分析 ,验正本方法的合理性     

趋势面分析在山西朔州王坪井田构造研究中的应用

针对王坪井田3号煤层底板起伏变化大．严重影响开拓及采煤巷道布置的现状．利用趋势面分析的方法．分析了井田内的构造展布规律．研究表明．井田在主向斜的基础上．存在次级背斜和NE和NW两组断裂．与本区受到多期次的构造应力场作用相吻合．得出的3号煤层底板高程二次趋势面方程．可为3号煤层开拓及采煤巷道的设计提供地质依据．     

Conceptual study — An improved method to assess acidification in German streams by using benthic macroinvertebrates

The present study is based mainly upon the authors' hydrochemical and hydrobiological studies of small silicate streams in South-West Germany, principally in the Black Forest and the Odenwald.

The aim of the paper is the adaptation of a practically proven four-level biological classification system of different degrees of acidity using benthic maroinvertebrates to a five-level system of acidification of mainly upland streams with low buffer capacity. The main reason for such a five-class system is the Water Framework Directive of the European Union (EU WFD), which lays down a five-level classification system for the assessment of the ecological quality of waters.

The biological method of assessing the state of acidity for evaluation of the degree of anthropogenic acidification under the directive, and principles of the EU WFD, are also described. A list of 278 taxa of the macrozoobenthos has been reclassified from a four-level system to a five-level biological indication system, based upon the authors' scientific expertise and the latest references from literature of different acid sensitive areas in Germany.     

TOC changes in the process of thermal evolution of source rock and its controls

Through geological observation, simulation in laboratory and numerical modeling, the factors that control the changes in total organic content (TOC) of source rock have been studied. When the formula DTOC=(TOC0-TOC)/TOC0 (original organic carbon content in the rock) is used to measure the TOC (total organic carbon content) changes in the source rock through geological time, the degrees and directions of such changes are determined by losses and relative amounts both of organic and inorganic matter in the source rock. The DTOC equation, which is used to calculate the loss rate in the process of maturation for the source rock, is therefore obtained by analyzing the mass balance relations. For a certain type of source rock with a certain maturation history, the changes of its TOC respond only to the rates of hydrocarbon generation and expulsion. In actual cases of geological entities, DTOC generally ranges from -0.05 to 0.2, while the calculated reconversion coefficient (k) for organic carbon content remains between 0.90 and 1.25. Only in an ideal situation where there are extremely high rates of hydrocarbon generation and expulsion can the DTOC value experience significant changes, with k reaching up to 2.5. It is concluded, therefore, that the criterion for carbonates source rock assessment, based on reconverting the TOC to the value of its original state, may have overestimated the course of the "carbon-reduction", which is likely in many cases to make a poor source rock sound better.     

Study on the threshold value of organic enrichment of carbonate as gas source rocks

In this paper, calculations have been performed about gas quantity of generation, adsorption, dissolving in oil, dissolving in water, diffusion of unit area carbonate rocks at different geologic conditions in the Tarim basin. According to the material balance principle, the corresponding organic carbon content when gas started expelling from source rocks with separate phases has been worked out. We regard it as the theoretical threshold value (TOCmin) of gas source rocks under the same geologic condition. Based on the simulating calculation, a fact has been discovered that TOCmin decreases with the increasing source rocks thickness, decreases at the beginning and then increases with the increasing maturity and decreases with the better type of organic matter. TOCmin evaluation table of carbonate gas source rocks in the Tarim basin has been established. Investigations indicate that the TOCmin of carbonate gas source rocks varies greatly with the differences of geologic conditions, and gas source rocks cannot be evaluated with a unified TOC threshold value. And we also establish a preliminary evaluation table of TOC industrial threshold value, TOCgy, of carbonate gas source rocks in the Tarim basin.     

Nonlinear analysis of the three-dimensional datum transformation [conformal group ℂ7(3)]

 The weighted Procrustes algorithm is presented as a very effective tool for solving the three-dimensional datum transformation problem. In particular, the weighted Procrustes algorithm does not require any initial datum parameters for linearization or any iteration procedure. As a closed-form algorithm it only requires the values of Cartesian coordinates in both systems of reference. Where there is some prior information about the variance–covariance matrix of the two sets of Cartesian coordinates, also called pseudo-observations, the weighted Procrustes algorithm is able to incorporate such a quality property of the input data by means of a proper choice of weight matrix. Such a choice is based on a properly designed criterion matrix which is discussed in detail. Thanks to the weighted Procrustes algorithm, the problem of incorporating the stochasticity measures of both systems of coordinates involved in the seven parameter datum transformation problem [conformal group ℂ₇(3)] which is free of linearization and any iterative procedure can be considered to be solved. Illustrative examples are given. Received: 7 January 2002 / Accepted: 9 September 2002 Correspondence to: E. W. Grafarend     

2002年全球重大气候事件概述

全球气候仍为异常暖年。赤道中、东太平洋形成新的ENSO暖事件。冬季前期连续大雪严寒席卷了欧洲大部地区，美国南部也受到罕见大雪袭击。南亚东部、中南半岛湄公河三角洲雨季降水频繁，引发严重洪涝灾害。8月，欧洲异常暴雨引发世纪大洪水，多国受灾严重。印度尼西亚、澳大利亚、美国西部、非洲大部降水持续偏少，发生严重干旱。太平洋、大西洋的热带风暴给沿岸国家带来不同程度的灾害。     

错格实数傅里叶变换微分算子及其在非均匀介质波动传播研究中的应用

提出一种新的数值微分运算方法，即错格实数傅里叶变换微 分法. 该方法的运算速度 比错格复数傅里叶变换数值微分解法快0.33倍；因为该微分算法在整个微分运算过程中保留 了奈奎斯特分量，使得它比普通分格的实数傅里叶变换数值微分算法的精度高，稳定性好. 将该方法和Cagniard De Hoop解析法在求解半无限空间地震波动的问题中进行比较，结果 表明，新微分法的精度和解析方法的精度相同. 在非均匀介质中的地震波传播数值模拟的结 果表明，该方法是一种研究非均匀介质中地震波传播问题的有效的数值微分方法.     

西藏自治区旅游资源概况

西藏地区经历了复杂的地质作用，造就了其地形的独特性，从而形成了独有的地貌特征，自然资源中具有旅游开发价值的为数不少。在旅游业兴盛繁荣的今天，挖掘并开放西藏的旅游资源已显得相当重要。本文在介绍西藏旅游资源概况的基础上，讨论了开发西藏自治区旅游资源的意义和作用。