多尺度孔隙岩石的核磁共振扩散耦合现象及其探测方法

油藏岩石的孔隙连通性是反映流体渗流难易程度的重要参数,对渗透率、有效孔隙度等岩石物理参数的评价具有重要作用.连通的孔隙中,核磁共振(NMR)弛豫的交换会产生扩散耦合现象,可作为孔隙连通性的表征和探测方法.本文提出利用横向弛豫T 2-T 2脉冲序列测量岩石的扩散耦合现象.运用随机游走方法模拟多孔岩石的核磁共振响应特征,分析扩散耦合的影响因素,推导表征扩散耦合强度的弛豫交换速率计算公式.结果表明:孔隙间的扩散耦合强度与T 2-T 2脉冲序列的混合时间呈正相关性,基于双孔弛豫交换模型推导的弛豫交换速率计算公式能够准确表征双尺度孔隙系统的扩散耦合强度.在孔隙尺寸不满足快扩散条件时,会出现与扩散耦合无关的非对角峰信号.针对含多类型孔隙的碳酸盐岩模型,随混合时间的增加,扩散耦合强度变大,一维T 2谱的形态畸变程度加重,在T 2-T 2二维谱中,代表微裂缝、粒间小孔、溶蚀大孔的信号能量变化趋势不同,反映不同类型孔隙间的连通性存在差异.本文的分析与讨论丰富了核磁共振弛豫在岩石物理性质评价中的应用方向,对利用核磁共振评价复杂孔隙岩石的孔隙结构和连通性提供了新思路和新方法.     

Antipodal effects of lunar basin-forming impacts: Initial 3D simulations and comparisons with observations

3D simulations of basin-scale lunar impacts are carried out to investigate: (a) the origins of strong crustal magnetic fields and unusual terrain observed to occur in regions antipodal to young large basins; and (b) the origin of enhanced magnetic and geochemical anomalies along the northwest periphery of the South Pole-Aitken (SPA) basin. The simulations demonstrate that a basin-forming impact produces a massive, hot, partially ionized cloud of vapor and melt that expands thermally around the Moon, converging near the basin antipode approximately 1 h after the impact for typical impact parameters. In agreement with previous work, analytic calculations of the interaction of this vapor-melt cloud with an initial ambient magnetic field predict a substantial temporary increase in field intensity in the antipodal region. The time of maximum field amplification coincides with a period when impacting ejecta also converge near the antipode. The latter produce antipodal shock stresses within the range of 5-25 GPa where stable shock remanent magnetization (SRM) of lunar soils has been found experimentally to occur. Calculated antipodal ejecta thicknesses are only marginally sufficient to explain the amplitudes of observed magnetic anomalies if mean magnetization intensities are comparable to those produced experimentally. This suggests that pre-existing ejecta materials, which would also contain abundant metallic iron remanence carriers, may be important anomaly sources, a possibility that is consistent with enhanced magnetic anomalies observed peripheral to SPA. The latter anomalies may be produced by amplified secondary ejecta impact shock waves in the thick SPA ejecta mantle occurring near the antipodes of the Imbrium and Serenitatis impacts. Together with converging seismic compressional waves, these antipodal impact shocks may have produced especially deep fracture zones along the northwest edge of SPA near the Imbrium antipode, allowing the ascent of magma with enhanced KREEP concentrations.     

Experimental test of a radiative transfer model of the optical effects of space weathering

We compare laboratory measurements of the optical effects of nanophase iron on near-IR reflectance spectra of transparent silica gel infused with small iron particles [Noble, S.K., Pieters, C.M., Keller, L.P., 2007. Icarus 192, 629-642] with a radiative transfer model of the process [Hapke, B., 2001. J. Geophys. Res. 106 (E5), 10039-10074]. We find that the measurements exhibit reddening and darkening effects of nanophase (<50 nm) iron particles, a darkening effect of somewhat larger particles (>50 nm) and mixing effects of silica gel particles of varying total iron abundance. The radiative transfer model reproduces the effects of nanophase iron within the experimental uncertainties.     

月球资源探测信息的管理与可视化探讨

在中国未来的月球探测计划中,可能获取的月球表层数据包括地形、地貌、岩层、土壤、资源、环境以及各种相关的结构、物质成分数据。这些数据既有空间数据,也有属性数据。为了实现月球资源探测工作信息化,可以借鉴“数字地球”的理念并采用“多S”结合与集成化技术,对所获取的海量月球表层数据进行一体化存贮管理,构建一个“数字月球”并实现其空间数据和属性数据之间的双向查询检索,以及对表层复杂结构信息分析的可视化。     

网格GIS及其在数字油田中的应用探讨

数字油田是解决当前油田智能化管理问题的最好途径。该文分析了当前油田建设中所面临的问题,结合油田在勘探开发中的实际需要,特别就当前数字油田建设中所面临的共性问题,在分析现有油田技术及发展需求的基础上,指出了基于中间件的分布式网格GIS技术是解决当前数字油田领域中所存在的问题的最佳方式,并讨论了其实现过程。     

High resolution facies architecture and digital outcrop modeling of the Sandakan formation sandstone reservoir,Borneo:Implications for reservoir characterization and flow simulation

Advances in photogrammetry have eased the acquisition of high-resolution digital information from outcrops, enabling faster, non-destructive data capturing and improved reservoir modeling. Geocellular models for flow dynamics with in the virtual outcrop in siliciclastic deposits at different sets of sandstone facies architecture remain, however, a challenge. Digital maps of bedding, lithological contrast, spatial-temporal variations of bedding and permeability characteristics make it more easy to understand flow tortuosity in a particular architecture. An ability to precisely model these properties can improve reservoir characterization and flow modeling at different scales. Here we demonstrate the construction of realistic 2 D sandstone facies based models for a pragmatic simulation of flow dynamics using a combination of digital point clouds dataset acquired from LiDAR and field investigation of the Sandakan Formation, Sabah, Borneo.Additionally, we present methods for enhancing the accuracy of outcrop digital datasets for producing high resolution flow simulation. A well-exposed outcrop from the Sandakan Formation, Sabah, northwest Borneo having a lateral extent of 750 m was chosen in order to implement our research approach. Sandstone facies and its connectivity are well constrained by outcrop observations, data from air-permeability measurements, bilinear interpolation of permeability, grid construction and water vector analysis for flow dynamics.These proportions were then enumerated in terms of static digital outcrop model(DOM) and facies model based on sandstone facies bedding characteristics. Flow simulation of water vector analysis through each of the four sandstone facies types show persistent spatial correlation of permeability that align with either cross-bedded orientation or straight with more dispersion high quality sandstone(porosity 21.25%-41.2%and permeability 1265.20-5986.25 mD) and moderate quality sandstone(porosity 10.44%-28.75% and permeability 21.44-1023.33 mD). Whereas, in more heterolithic sandstone(wavy-to flaser-bedded and bioturbated sandstone), lateral variations in permeability show spatially non-correlated patterns over centimeters to tens of meters with mostly of low quality sandstone(porosity 3.4%-12.31% and permeability < 1 mD to 3.21 mD). These variations reflect the lateral juxtaposition in flow dynamics. It has also been resulted that the vertical connectivity and heterogeneities in terms of flow are mostly pragmatic due to the interconnected sandstone rather than the quality of sandstone.     

怀4井数字化水位观测资料初步分析

介绍了怀4井的地质构造情况和怀4井数字化水位观测资料的特征。分析了该井水位观测资料潮汐效应,同时指出了影响该井水位观测质量的干扰因素,加深了对怀4井水位资料的认识,有助于今后分析预报水平的提高。     

黄土高原沟谷地貌发育演化研究进展与展望

黄土沟谷是黄土地貌中最有活力、最具变化、最富特色的对象单元,黄土高原千沟万壑的地貌形态以及触目惊心的侵蚀状态也让区域内沟谷地貌的形成、发育及演化问题成为研究中焦点及前沿性科学问题。近年来,诸多学者采用地学测年法、特征表达法、监测模拟法力图实现对黄土沟谷发育演化进程中“过去-现代-未来”的科学认知。这些研究在相当程度上丰富了黄土沟谷发育过程的认知。本文梳理了黄土高原沟谷地貌演化相关研究的现状,并从黄土高原地貌演化、黄土沟谷发育、基于DEM的沟谷信息提取与表达等研究进行了系统的回顾、梳理与分析。此外,本文提出“黄土沟道剖面群组”概念与方法,试图从新的视角审视黄土沟谷地貌发育演化过程。沟道剖面在黄土沟谷发育演化进程中传递物质能量和累积地形动力,并通过径流节点的串联实现剖面群的连接与组合,形成独特的剖面“群组”模式;该沟道剖面群组是集黄土沟谷地貌特征与过程于一体的综合信息集成体,其三维空间结构是对黄土沟谷地貌发育演化的高度抽象与映射,并可望进一步丰富黄土高原数字地形分析理论与方法体系,为黄土高原黄土地貌成因机理与空间分异格局带来创新的认识。     

A digital earth platform for sustainability

ABSTRACT

Based on the experience of the International Society for Digital Earth (ISDE), this paper describes some challenges foreseen in order to develop a Digital Earth platform that can support the implementation of the Sustainable Development Goals. The use of ready-to-use derived geospatial information is essential. Future Earth’s methodology of ‘co-design’ aims to bring together natural, social scientists and decision makers to plan and carry out research for sustainability. Sustainability implies transdisciplinary research, but in order for scientists of different disciplines to work together, they will need to be able to share, access and use common data. This is by far not simple! While the good will to share data might exist, the associated technological, ethical and privacy issues are difficult to solve. An adequate e-infrastructure will be required. ISDE could consider to use the SDGs is the basis to develop the desired Digital Earth platform. This paper, by no means, covers everything for a Digital Earth platform, it aims to trigger research discussions and to have a good view about a starting point.     

Spheroidal equal angular DEMs: The specificity of morphometric treatment

Digital elevation models (DEMs) are commonly constructed using two main types of regular grids: plane square grids and spheroidal equal angular grids. Methods and algorithms intended for plane square‐gridded DEMs should not be directly applied to spheroidal equal angular DEMs. This is because these grids have fundamentally different geometry. However, some researchers continue to apply square‐grid algorithms to spheroidal equal angular DEMs. It seems appropriate to consider once again the specifity of morphometric treatment of spheroidal equal angular DEMs. This article, first, demonstrates possibilities of direct calculation of local, nonlocal, and combined morphometric variables from spheroidal equal angular DEMs exemplified by slope gradient, catchment area, and topographic index. Second, the article shows computational errors when algorithms for plane square‐gridded DEMs are unreasonably applied to spheroidal equal angular DEMs. The study is exemplified by two DEMs. A medium‐resolution DEM of a relatively small, high‐mountainous area (Mount Elbrus) was extracted from the SRTM1 DEM. A low‐resolution DEM of a vast region with the diverse topography (the central and western regions of Kenya) was extracted from the SRTM30_PLUS DEM. The results show that application of square‐grid methods to spheroidal equal angular DEMs leads to substantial computational errors in models of morphometric variables.