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71.
北部湾盆地涠西南油田群是南海西部重要的原油产区,同时油田群紧邻众多国家级自然保护区,属于环境敏感区域。针对北部湾盆地涠西南地区环保要求,以及涠洲组和流沙港组钻井过程经常出现井壁失稳导致的憋卡、起下钻阻卡等问题,开展了涠西南地区地层泥页岩特性及环保钻井液技术研究。通过地层岩石黏土矿物分析、孔喉结构分析以及理化性能评价,明确了涠西南地区泥页岩井壁失稳的机理;提出以类油基的水溶性复合基基液为核心,构建了一套具有油基钻井液工程特性和水基钻井液环保特性的新型环保防塌钻井液技术,并进行了相关的现场应用。现场应用显示:应用井与邻井相比,12-1/4″井段阻卡划眼时间减少,井径扩大率大幅度降低,并且在128 h的长时间浸泡过程中没有复杂情况产生,有效地解决了涠洲组、流沙港组易失稳地层的井壁稳定问题;同时,钻井液环保性能达到一级海域环保要求,可以替代目前应用的油基钻井液体系,解决了海上使用油基钻井液存在配制成本高、含油钻屑需全回收及环境危害隐患大等技术难题。该研究对于涠西南油田环保、井壁失稳和钻井液技术发展具有较高的理论价值和借鉴意义。 相似文献
72.
Ricard A Cernogora G Fitaire M Hochard L Kouassi N Speller C Vacher JR 《Planetary and Space Science》1995,43(1-2):41-46
The kinetic reactions in N2-xCH4(C2H2) gas discharges with x less than 1% have been studied by emission spectroscopy in the afterglow of D.C. discharges and by mass spectroscopy from radiolysis ionization using alpha particles. The pressure range is from several Torr to 100 Torr. At the end of N2 D.C. discharges at room temperature, for a residence time of about 10(-2) s, the dominant active species are the N atoms with density of 10(14)-10(15) cm-3 for N2 density of about 10(17) cm-3 (3 Torr), the N2(X,V) vibrational molecules with for example [N2(X,V = 10)] approximately 10(14) cm-3 and the electronic metastable molecules N2(A 3 sigma u +) with a density of 10(12) cm-3. In such conditions, the following kinetic reactions have been studied: N2(A) + N2(A) --> N2(C,B,V') + N2(X), N2(A) + N2(X,V>5) --> N2(X) + N2(B,V') in pure N2 post-discharges and N2(A) + CH4 --> products, C + N + M2 --> CN(B,V') + M2, N2(X,V>4) + CN --> N2(X) + CN(B,A,V'), in N2-1% CH4 post-discharges. The clustering reactions of N2-(1-5%)CH4(C2H2) gas mixtures after radiolysis ionization have been studied for the H2CN+ nN2 ions and the equilibrium constants have been determined in the temperature range T = 140-300 K. 相似文献
73.
Ahmad A 《Population geography : a journal of the Association of Population Geographers of India》1995,17(1-2):7-14
"This paper documents the current evidence of the state of the Tibetan society in India with special reference to the trends in social transformation, livelihood patterns and cultural adaptation to a geographically alien environment....Three-and-a-half decades of living in India [have] demonstrated how a culture group can survive by carving out ecological niches in ethnically segregated social space and yet adapt to a new cultural environment without losing its identity." 相似文献
74.
"Debates concerning the origins and development of the late nineteenth- to early twentieth-century declines in marital fertility and infant mortality in England and Wales have been centred largely on the material provided by answers to the ?special' questions in the 1911 census. In their published form these figures have restricted researchers to an examination of large scale geographic and social class differences in the levels and rates of decline of the two phenomena. This paper outlines research conducted on a sample of individual census returns from the 1911 census. From this data it becomes clear that for Victorian and Edwardian England ?where one lived' was rather more important than ?who one was' in determining both family building strategies and the survival of those children born." 相似文献
75.
Avanesov G Zhukov B Ziman YA Kostenko V Kuzmin A Murav'ev V Fedotov V Bonev B Mishev D Petkov D Krumov A Simeonov S Boycheva V Uzunov YU Weide GG Halmann D Pössel W Head J Murchie S Schkuratov YuG Berghänel R Danz M Mangoldt T Pihan U Smith B 《Planetary and Space Science》1991,39(1-2):281-295
From February to March 1989 the Phobos 2 spacecraft took 37 TV images of Phobos at a distance of 190-1100 km. These images complement Mariner-9 and Viking data by providing higher-resolution coverage of a large region West of the crater Stickney (40-160 degrees W) and by providing disk-resolved measurements of surface brightness at a greater range of wavelengths and additional phase angles. These images have supported updated mapping and characterization of large craters and grooves, and have provided additional observations of craters' and grooves' bright rims. Variations in surface visible/near-infrared color ratio of almost a factor of 2 have been recognized; these variations appear to be associated with the ejecta of specific large impact craters. Updated determinations of satellite mass and volume allow calculation of a more accurate value of bulk density, 1.90 +/- 0.1 g cm-3. This is significantly lower than the density of meteoritic analogs to Phobos' surface, suggesting a porous interior perhaps containing interstitial ice. 相似文献
76.
内蒙古正镶白旗碎斑熔岩岩石学特征及其岩相划分 总被引:4,自引:0,他引:4
白旗碎斑熔岩为不规则穹状体,可分为边缘玻质碎斑熔岩、过渡霏细碎斑熔岩、中心粒状碎斑熔岩和根部花岗斑岩四个岩性带。从玻质碎斑熔岩到粒状碎斑熔岩,斑晶碎裂度逐渐减弱,珠边结构在粒状碎斑熔岩中最发育,根部花岗斑岩与正常次火山岩相近。碎斑熔岩中钾长石有序度低,指示了岩石高温成因特征。白旌碎斑熔岩属太平洋岩系钙碱质系列,原始岩浆由来源于上地幔和下地壳熔体的混熔作用形成。 相似文献
77.
密坑山锡矿田位于江西省会昌县西南约40km处。该区为一晚中生代破火山,火山岩为上侏罗统鸡笼嶂组流纹质凝灰熔岩及火山碎屑岩,火山口周围环状及放射状断裂发育,火山口中心为浅成相的密坑山似斑状钾长花岗岩中央岩株侵入体所充填。上世纪80年代以来,在该岩体与流纹质凝灰熔岩的内外接触带相继发现了岩背、淘锡坝、苦竹岽、矿背、上湾等一批大、中型锡多金属矿床或矿点,表明这一岩体对成矿具有重要的制约作用。 相似文献
78.
Mohammad S. Al-Hwaiti Robert A. Zielinski James R. Budahn James F. Ranville Philippe E. Ross 《中国地球化学学报》2006,25(B08):178-178
Phosphogypsum is a waste by-product of the phosphate fertilizer industry that has relatively high concentrations of some U decay-series radionuclides such as ^226Ra and ^210Pb. The distribution and environmental mobility of radionuclides in phosphogypsum are an important concern because this gypsum by-product is used for wallboard, in agriculture and as a soil amendment. This study determined the distribution of ^226Ra, ^210Pb, within phosphogypsum stacks of varying age and among three size fractions (coarse: 〈0.212 mm; medium: 0.212-0.053 mm; fine: 〈0.053 mm), in phosphogypsum derived from Aqaba and Eshidiya fertilizer plants. The results indicated that ^226Ra and ^210Pb were generally uniformly distributed in phosphogypsum stacks and showed no significant difference in the concentration of these elements with the age of stack. In the Aqaba phosphogypsum ^226Ra was slightly 10% enriched in the coarse fraction, while ^210Pb was 10% enriched in the free size fraction. In the Eshidiya phosphogypsum ^226Ra and ^210Pb contents were both relatively enriched (10%) in the fine size fraction. 相似文献
79.
Mohammad Rasul Jan Mahmood A Khawaja Jasmin Sha Kashif Gul 《中国地球化学学报》2006,25(B08):182-182
Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The factory was established in 1963 and remained in operation till 1994. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analysis. Physical parameters for the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using soxhlet extraction apparatus. The extract was transferred to well washed, clean; dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples was identified on the basis of their retention time and quantified on the basis of peak areas. It is evident from the analytical data obtained in the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory since the past few years. 相似文献
80.
Michael H. Ramsey Paul D. Taylor Katy A. Boon 《中国地球化学学报》2006,25(B08):209-210
All geochemical measurements require the taking of field samples, but the uncertainty that this process causes is often ignored when assessing the reliability of the interpretation, of the geochemistry or the health implications. Recently devised methods for the estimation, optimisation and reduction of this uncertainty have been evaluated by their application to the investigation of contaminated land. Uncertainty of measurement caused by primary sampling has been estimated for a range of six different contaminated land site investigations, using an increasingly recognized procedure. These site investigations were selected to reflect a wide range of different sizes, contaminants (organic and metals), previous land uses (e.g. tin mining, railway sidings and gas works), intended future use (housing to nature reserves) and routinely applied sampling methods. The results showed that the uncertainty on measurements was substantial, ranging from 25% to 186% of the concentration values at the different sites. Sampling was identified as the dominant source of the uncertainty (〉70% of measurement uncertainty) in most cases. The fitness-for-purpose of the measurements was judged using the optimized contaminated land investigation (OCLI) method. This identifies the optimal level of uncertainty that reduces to overall financial loss caused by the measurement procedures and the misclassification of the contamination, caused by the uncertainty. Generally the uncertainty of the actual measurements made in these different site investigations was found to be sub-optimal, and too large by a factor of approximately two. The uncertainty is usually limited by the sampling, but this can be reduced by increasing the sample mass by a factor of 4 (predicted by sampling theory). It is concluded that knowing the value of the uncertainty enables the interpretation to be made more reliable, and that sampling is the main factor limiting most investigations. This new approach quantifies this problem for the first time, and allows sampling procedures to be critically evaluated, and modified, to improve the reliability of the geochemical assessment. 相似文献