激发极化法的测量精度及其对应用的影响

本文在频率域和时间域激电二者等效的前提下,研究了在保证激电响应参数达到必须精度时,对电位差测量的精度要求.时间城激电对电位差的相对精度要求不高,但供电电流大,装备笨重.变频法对电位差的相对精度提出了很高的要求,在极化率低时,难于达到.双频激电由于同时测量双频电位差,电位差差值具有很高的相对精度,因而既轻便又能很好地满足精度要求.     

Interpreting Dual Laterolog Fracture Data in Fractured Carbonate Formation

The estimation of fractures is key to evaluating fractured carbonate reservoirs. It is difficult to evaluate this kind of reservoir because of its heterogeneously distributed fractures and anisotropy, A three-dimensional numerical model was used to simulate the responses of the dual laterolog （DLL） in a fractured formation based on a macro-isotropic anisotropic model, Accordingly, a fast fracture computing method was developed. First, the apparent conductivity of the DLL is linearly related to the porosity of the fracture and the conductivity of pore fluid. Second, the amplitude difference of the deep and shallow apparent resistivity logs is mainly dependent on the dip angle of the fracture. Then the response of the DLL to a formation with dip angle fractures is approximately depicted as a function of the bulk resistivity of the rock, the porosity of the fractures and the conductivity of fracture fluid. This function can be used to compute the porosity of fracture quickly. The actual data show that the fracture parameters determined by the DLL closely coincide with the formation micro imager log.     

地震激发井深与品质因数的关系

通过对地震波在近地表附近双源传递机理的研究,论述了品质因数与激发井深的关系,并根据不同地区、不同品质因数,其地震波最大激发能量、最大信噪比与激发井深的关系曲线,给出了相应的激发深度.三维地震实例表明,地震波在近地表附近的双源传递与品质因数是选择地震波激发井深的重要因素,另外激发频率的增大,对激发井深的影响程度随之增大;观测同样频率的地震信号,存在小Q值地震波激发井深较大Q值激发井深相应变小的特点.     

Residual errors in altimetry data detected by combinations of single- and dual-satellite crossovers

 The single- and dual-satellite crossover (SSC and DSC) residuals between and among Geosat, TOPEX/Poseidon (T/P), and ERS 1 or 2 have been used for various purposes, applied in geodesy for gravity field accuracy assessments and determination as well as in oceanography. The theory is presented and various examples are given of certain combinations of SSC and DSC that test for residual altimetry data errors, mostly of non-gravitational origin, of the order of a few centimeters. There are four types of basic DSCs and 12 independent combinations of them in pairs which have been found useful in the present work. These are defined in terms of the `mean' and `variable' components of a satellite's geopotential orbit error from Rosborough's 1st-order analytical theory. The remaining small errors, after all altimeter data corrections are applied and the relative offset of coordinate frames between altimetry missions removed, are statistically evaluated by means of the Student distribution. The remaining signal of `non-gravitational' origin can in some cases be attributed to the main ocean currents which were not accounted for among the media or sea-surface corrections. In future, they may be resolved by a long-term global circulation model. Experience with two current models, neither of which are found either to cover the most critical missions (Geosat & TOPEX/Poseidon) or to have the accuracy and resolution necessary to account for the strongest anomalies found across them, is described. In other cases, the residual signal is due to errors in tides, altimeter delay corrections or El Ni?o. (Various examples of these are also presented.) Tests of the combinations of the JGM 3-based DSC residuals show that overall the long-term data now available are well suited for a gravity field inversion refining JGM 3 for low- and resonant-order geopotential harmonics whose signatures are clearly seen in the basic DSC and SSC sets. Received: 15 January 1999 / Accepted: 9 September 1999     

X波段双偏振天气雷达衰减订正方法及效果检验

X波段双偏振天气雷达在观测强降水时衰减较大,双偏振雷达的相位参数因衰减较小可用于反射率的衰减订正。自适应算法和差传播相移率K_(DP)订正法是应用较多的两种衰减订正算法,这两种方法均采用了差分参数实现衰减订正。自适应算法实现因难,但能够根据不同降水类型对订正系数进行调整,而K_(DP)订正法则无法实现。本文在自适应算法和K_(DP)订正法衰减订正的基础上提出了K_(DP)综合分类法,该算法实现简单,并分别采用三种方法完成衰减订正,然后对订正效果进行了比较分析,并与S波段雷达进行了对比。最后将订正前后的反射率联合地面降水资料进行对比研究,结果显示订正后反射率更适合观测降水及反演雨强。     

新型水氡仪质量检测及台站比测实验研究

针对目前地震水氡模拟观测操作繁琐、干扰因素多等现状,引入新型水氡观测仪进行检测并与FD-125测氡仪开展对比试验研究。两款水氡观测仪在地震监测氡观测仪检测平台标准氡室校准,并依托九江地震台相同水样和环境下开展对比测量表明,在静置时间为1 h前提下,新型水氡观测仪重复性、相对误差、相对固有误差、固有本底符合技术要求,与FD-125测氡仪对比测量数据的一致性较好,但灵敏度指标有待提升。该仪器整体设计基本满足地震模拟水氡测量发展需求,可减少人工操作带来的测量误差,提升测量效率和数据质量。     

对偶四元数GPS辅助光束法区域网平差

针对GPS辅助光束法区域网平差中线元素和角元素分而治之引起转动和平移的耦合误差问题,该文提出了一种基于对偶四元数的GPS辅助光束法区域网平差方法。利用对偶四元数统一描述像空间坐标系与WGS84坐标系之间的旋转和平移关系,建立对偶四元数GPS辅助光束法区域网平差模型,实现了区域网影像外方位元素以及待定点WGS84坐标的平差解算。实验结果表明,本算法具有对迭代初值无依赖性、迭代次数少和精度高的优点,为姿态稳定较差的轻小无人机影像的GPS辅助光束法区域网平差提供了一种新的思路。     

一种基于相对关系不变性的双相机标志点匹配算法

针对双相机数字工业摄影测量中的人工标志点自动匹配问题,设计了一种基于相对关系不变性的图像匹配算法,根据平缓过渡曲面上相邻点间相对关系在两张像片上一致的原理,解决了两张像片的标志点自动匹配问题。3组实验表明,该算法匹配正确率高,匹配速度快,能够满足动态测量数据处理的需求。     

RMR技术在海域天然气水合物钻探中的适应性分析

深水表层天然气水合物沉积体埋藏浅、地层软、未固结,泥浆密度窗口窄,使用常规隔水管泥浆循环钻进钻遇水合物分解会引起井周孔隙压力及储层水合物饱和度发生变化,导致水合物储层泥浆密度窗口更窄,引发井壁以及井口失稳等问题,并且时间长、成本高。文章介绍了无隔水管泥浆回收(RMR)技术原理,对该技术在深水表层海域天然气水合物钻探中的适应性进行了分析。结果表明,RMR技术利用双梯度原理,能有效解决目前深水表层钻井窄密度窗口难题;实时监控系统提高遇险机动性,严防硫化氢等气体发生泄漏;能够简化井身结构,缩短建井周期,降低建井成本;同时对海洋零排放,安全环保。     

大同盆地北部油气预查钻井工程实践

大同盆地北部油气预查施工区地层主要为泥岩、砂质泥岩、炭质泥岩和砂砾岩不等厚互层。上部砂砾层胶结松散、破碎,易掉块坍塌;泥岩水敏性强,易分散造浆,护壁困难,钻进中易产生卡钻及粘附卡钻。设计井深一般为1000～3000 m,钻进中合理采用了不同类型、结构的钻头,钻具和取心工具,调整了钻进技术参数,并选用了双聚-成膜无固相钻井液体系及其它相应的工艺技术措施,孔壁稳定,保证了正常施工。其中也顺利完成了侧钻井施工任务,均取得了较好的效果。