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241.
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头台油田是构造—岩性油藏。裂缝型、特低渗透是其显著特点,常规注水开发后经常出现严重的油井水淹,造成油田开发低效。本文以头台油田研究为例,认为对于裂缝型特低渗透油田,采用注水吞吐采油技术,通过套管直接向地层注水,利用储层毛管力作用,进行油水置换,实现单井自注自采吞吐采油,可以改善油田开发效果,减缓产量递减。适合注水吞吐采油基本条件是岩石润湿性为弱亲水和岩石饱和非润湿相。影响注水吞吐采油效果的主要因素是储层吸水状况、微缝发育状况、储层非均质性、注入体积和关井压力等。吞吐采油技术可作为改善裂缝型特低渗透油藏开发效果的一种新的模式来研究和推广。 相似文献
243.
以农安幅1:20万综合水文地质图空间数据库的建立为例,介绍了利用GIS建立空间数据库的全过程。讨论了建库过程中的主要操作步骤、方法和一些值得注意的问题。着重讨论在图形数据采集及建立空间属性数据库时,如何保证图形的数学精度,如何使拓扑结构合理,以及如何使属性联接正确。 相似文献
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地氟病属于"钙矛盾疾病" 总被引:14,自引:0,他引:14
膳食低钙是地氟病病区居民中的普遍现象,是地氟病(氟骨症)的主要促发和加重因素。低钙的作用不仅在于增如肠道氟的吸收,更在于它和过量氟同样都可引起甲状旁腺激素分泌增多,都可促进成骨、破骨功能活跃。过量氟可进一步加重机体缺钙。我们最近的研究证明,氟中毒大鼠肝、肾、脑组织Ca^2 ]i升高,培养的成骨细胞样细胞染氟后细胞内钙亦增加;即氟中毒存在着全身缺钙继而细胞内钙增多的钙矛盾现象,属于钙矛盾疾病。为控制和消除地氟病危害,应把减少氟的摄入和改善居民钙营养两结合起来。 相似文献
246.
LIU Shen HU Ruizhong FENG Caixi CHI Xiaoguo LI Cai YANG Rihong WANG Tianwu JIN WeiGuiyang Institute of Geochemistry Chinese Academy of Sciences Guiyang Guizhou E-mail: lliushen@hotmail.comGraduate School of the Chinese Academy of Sciences Beijing College of Earth Sciences Jilin University Changchun Jilin Aero Geophysical & Remote Sensing Center Beijing 《《地质学报》英文版》2003,77(2):187-193
Volcanic rocks in the study area, including dacite, trachyandesite and mugearite, belong to the intermediate-acid, high-K calc-alkaline series, and possess the characteristics of adakite. The geochemistry of the rocks shows that the rocks are characterized by SiO2>59%, enrichment in A12O3(15.09-15.64%) and Na2O (>3.6%), high Sr (649-885 μg/g) and Sc, low Y contents (<17 μg/g), depletion in HREE (Yb<1.22 μg/g), (La/Yb)N>25, Sr/Y>40, MgO<3% (Mg<0.35), weak Eu anomaly (Eu/Eu=0.84-0.94), and lack of the high field strength elements (HFSE) (Nb, Ta, Ti, etc.). The Nd and Sr isotope data (87Sr/86Sr=0.7062-0.7079, 143Nd/144Nd=0.51166-0.51253, εNd= -18.61-0.02), show that the magma resulted from partial melting (10%-40%) of newly underplated basaltic lower crust under high pressure (1-4 GPa), and the petrogenesis is obviously affected by the crust's assimilation and fractional crystallization (AFC). This research will give an insight into the uplift mechanism of the Tibetan plateau. 相似文献
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248.
城市土地利用的空间分布特征一直是城市地理和城市规划领域关注的重点问题,对城市土地利用空间模式的研究有助于理解城市系统的运行状态。在分析现有城市空间结构和城市土地利用模式的基础上,从两个方面对现有基于富集因子的分析方法提出改进,一是采用矢量网格以减少分析的误差,二是采用斜网格和曼哈顿距离来对空间临近关系进行界定。采用这一方法对深圳市2015年6类城市土地利用数据进行分析,得到邻里尺度上各类用地之间富集度随距离变化的3种模式。模式I中,同类用地间的富集度在短距离内较大,且其值随着距离的增加而减小并趋于0,表明同类用地间在较短距离内相互吸引,而吸引力随着距离增加而减弱。在不同类型用地间的模式II和模式III中,富集度在较短距离内为负值,但是在模式II中,富集度随着距离的增加而逐渐增加并趋于0,表明不同用地间短距离内相互排斥,且排斥作用随着距离增加而减弱;而在模式III中,富集度则随着距离增加而快速上升到正值,然后逐渐下降并趋于0,表明不同类型用地在较短距离内相互排斥,但随着距离增加很快变为相互吸引,最后吸引力随着距离增加慢慢减弱。结果表明,相对于基于栅格网的分析方法,基于矢量斜网格的分析方法能够显著降低分析误差。 相似文献
249.
Benefit sharing on transboundary rivers is an approach to address equitable and reasonable development and utilization of transboundary water resources (TWR). Through analyzing a few typical benefit sharing cases, this paper provides a systematic discussion of the theory of TWR benefits sharing. TWR features a kind of common pool resources (CPRs). Its benefit sharing subjects are the riparian countries. The shared benefits usually include flood prevention, power generation, navigation, irrigation, contributions to society and culture, etc. The benefit sharing modes mainly include shared benefits and responsibilities, reciprocal rights and obligations, equal benefit distribution, cost proportion-based benefit sharing, and demand-based benefit sharing. The first step in the realization process of benefit sharing is the sharing of data and information. Second is the benefit identification and evaluation. Third is the establishment of a mechanism to guarantee the benefit sharing. The conditions for realizing benefit sharing depends on, first, if the riparian countries are willing to cooperate with each other; second, whether the cooperation can bring incremental benefit or cost reduction in comparison with unilateral operation; and third, if the benefit distribution is equitable and reasonable and can stand the test of time. 相似文献
250.
Yalin Wu Tao Huang Changchun Huang Yinyin Shen Yang Luo Hao Yang Yanhong Yu Ruixiao Li Yan Gao Mingli Zhang 《中国地理科学(英文版)》2018,28(5):851-862
Sediments have a significant influence on the cycling of nutrient elements in lake environments. In order to assess the distribution characteristics and estimate the bioavailability of phosphorus and nitrogen in Dianchi Lake, organic and inorganic phosphorus and nitrogen forms were analysed. The 210 Pb radiometric dating method was employed to study temporal changes in the phosphorus and nitrogen pools in Dianchi Lake. The result show that the total phosphorus(TP) and total nitrogen(TN) were both at high concentrations, ranging from 697.5–3210.0 mg/kg and 1263.7–7155.2 mg/kg, respectively. Inorganic phosphorus(IP) and total organic nitrogen(TON) were the main constituents, at percentages of 59%–78% and 74%–95%, respectively, in the sediments. Spatially, there was a decreasing trend in phosphorus and nitrogen contents from the south and north to the lake centre, which is related to the distribution pattern of local economic production. The burial rates of the various phosphorus and nitrogen forms increased in same spatially and over time. Particularly in the past two decades, the burial rates doubled, with that TN reached to 1.287 mg/(cm~2·yr) in 2014. As the most reactive forms, nitrate nitrogen(NO_3-N) and ammonia nitrogen(NH_4-N) were buried more rapidly in the south region, implying that the potential for releasing sedimentary nitrogen increased from north to south. Based on their concentrations and burial rates, the internal loads of phosphorus and nitrogen were analysed for the last century. A TP pool of 71597.6 t and a TN pool of 81191.7 t were estimated for Dianchi Lake. Bioavailable phosphorus and nitrogen pools were also estimated at 44468.0 t and 5429.7 t, respectively, for the last century. 相似文献