水资源可持续性的参数敏感性分析

通过界定敏感性参数的含义,认为参数的敏感性是系统对某一指参数的变化的敏感程度,以此为依据建立M-YAS模型分析参数的敏感性。以佛山市为例选取37 项影响水资源可持续的参数,分析水资源可持续性的参数敏感性问题,结果表明：37项反映水资源可持续性的参数中,仅13 项参数（生活用水定额、林牧渔畜用水量、工业用水定额、农田灌溉用水量、工业用水量、耕地灌溉定额、万元工业增加值用水量、火电冷却用水量、城乡生活用水量、工业节水、万元生产总值用水量、生活节水和农业节水）对于水资源可持续性的目标层而言是敏感性参数,且13项参数均来自用水结构与效率的准则层,说明区域水资源可持续性的目标层对用水结构与效率的准则层较为敏感。     

页岩气储层水平井压裂分布式光纤邻井微振动监测及震源位置成像

水力压裂是进行非常规油气储层改造,提高单井产量的必备技术.为了实现安全、高效压裂,通常使用地震检波器进行微地震监测和压裂效果评估.一般情况下,井中检波器数量较少且采集方位角较窄,难以获得准确的微地震震源位置,导致无法准确评估储层改造情况.通过将光纤永置式布设于页岩气储层水平井的套管外,我们实现了基于水平井光纤分布式声波传感（Distributed Acoustic Sensing,DAS）的全井段、宽方位、高密度水力压裂过程微振动实时监测,并进一步使用震源扫描算法对监测到的微地震有效事件进行震源位置成像.合成数据算例表明,与常规检波器技术相比,DAS技术具有以下两点优势：（1）DAS技术实现了水平井全井段监测,显著增加了监测数据的采集方位角,可以有效提升震源位置成像的空间分辨率;（2）DAS技术显著增加了监测数据的空间采样密度,可以有效提高低信噪比监测数据的震源位置成像精度.昭通页岩气储层水力压裂监测数据算例进一步验证了DAS技术的有效性,表明了宽方位、高密度的DAS数据可以获得高分辨率的震源位置成像结果,有助于提高储层改造效果评估的准确性.

     

Remote Sensing of Eupatorium Adenophorum Spreng Based on HJ-A Satellite Data

In the southwest of China, one of the greatest threats to local ecosystem is the area expansion of an invasive species, i.e., Eupatorium adenophorum Spreng (EAS). In this study, the remote-sensing technology was used to detect and map the spatial distribution of EAS in Guizhou Province, China. A series of vegetation indices, including normalized difference vegetation index (NDVI), simple ratio index (SRI) and atmospherically resistant vegetation index (ARVI), were used to identify EAS from HJ-A Chninese satellite data. According to the analysis results of fieldworks from March 21 to 22, 2009, it was found that the vegetation index of {1.9589 ≤ SRI ≤ 4.1095}∩{0.2359 ≤ ARVI ≤ 0.5193} was the optimal remote-sensing parameter for identifying EAS from HJ-A data. According to the spatial distribution of EAS estimated from HJ-A data, it was found that EAS was rather more in southwest of Guizhou Province than in northeast. EAS became sparse from southwest to northeast gradually, and the central Guizhou Province was the ecological corridor linking EAS in southwest to that in northeast. By comparison with validated data collected by the government of Guizhou Province, it was found that the uncertainty of remote-sensing method was 18.52%, 29.31%, 8.77% and 9.46% in grassland, forest, farmland and others respectively, and the mean uncertainty was 13.29%. Owing to the lower height of EAS than many plants in forest, the uncertainty of EAS was the greatest in forest than that in grassland, farmland and so on.     

Analysis of the Effect of Borehole Size on Explosive Energy Loss in Rock Blasting

In this paper, studies were conducted on the effect of borehole size on explosive energy loss in rock blasting. Since most industrial explosives are nonideal ones, the charge size and the confinement condition have significant impact on the detonation performance of these explosives. Analyses indicated that smaller boreholes will cause more loss of explosive energy than larger ones. This is especially true for most industrial explosives. The paper presents the analyses of energy loss for a number of different explosives with various borehole sizes. Based on these analyses recommendations and guidelines were given for borehole size determination in rock blasting operations.     

腾格里沙漠公路工程防沙效应

腾格里沙漠东北锡1井临探路虽然只有3km,却是真正修筑在流动沙丘区的第一条运输设备和石油的公路。沙区工程地质基础一般可满足公路建设的要求。防沙是工程成败的关键。这条路就地取材,利用盐渍土筑路和压沙防沙,取得了比较好的成效。     

Epithermal deposits in North Xinjiang, NW China

The North Xinjiang region (NW China) is an important part of the Central Asia Orogenic Belt, situated at the junction of Siberia, Tarim and Kazakhstan plates. It is an area characterized by multiple stages of Phanerozoic continental growth, during which several porphyry and epithermal systems were formed. The relationship of these mineral systems to the geodynamic evolution of the region has not yet been well understood. In this paper, we list the main geological characteristics of 21 significant epithermal precious and base metal deposits in North Xinjiang, and classify them into high-sulfidation and low-sulfidation styles, with the latter being predominant. We have selected seven epithermal deposits representing different styles formed under different tectonic regimes and discuss their geology and geochemistry in some detail. The deposit-scale geology and geochemistry of epithermal systems in North Xinjiang are essentially similar to those in other parts of the world. All epithermal deposits in North Xinjiang are hosted in volcanic rocks with ages ranging from Devonian to Triassic, with the Early Carboniferous volcanic sequences being the most important, followed by the Permian and Triassic. The Devonian–Early Carboniferous host rocks belong to the calc-alkaline series that developed in pre-collisional arc-back-arc basin systems; whereas the Permian–Triassic host volcanic rocks of shoshonite series formed in post-subduction regimes. Available isotopic ages of these epithermal systems cluster in two periods: Early Carboniferous (>320?Ma) and Late Carboniferous–Triassic (320–220?Ma), reflecting two metallogenic episodes that occurred during subduction-related accretion and post-subduction collision regimes, respectively. Accordingly, three groups of epithermal deposits in North Xinjiang can be recognized as (1) pre-collisional deposits without or with negligible collisional-related modification, (2) deposits formed in collision regime and (3) ore systems strongly overprinted by fluid flow in post-subduction collision regime.     

On the timing of the East Asian summer monsoon maximum during the Holocene—Does the speleothem oxygen isotope record reflect monsoon rainfall variability?

The evolution of the East Asian summer monsoon(EASM) during the Holocene has long been of significant interest.Knowledge of past EASM variability not only increases our understanding of monsoon dynamics on a long timescale,but it also provides an environmental and climatic background for research into Chinese cultural development.However,the timing of the EASM maximum remains controversial.The popular concept of an "early Holocene maximum" is mainly based on speleothemδ~(18)O(δ~(18)O_c) records from caves in southern China;however,the interpretation of δ~(18)O_C as a reliable proxy for EASM intensity is being increasingly challenged.The present paper is a critical review of the climatic significance of the δ~(18)O_C record from China.Firstly,we suggest that precipitation in northern China is an appropriate index of EASM intensity,the variation of which clearly indicates a mid-Holocene monsoon maximum.Secondly,an interregional comparison demonstrates that the precipitation record in northern China is quite different from that in southern China on a range of timescales,and is inconsistent with the spatial similarity exhibited by speleothem oxygen isotope records.Furthermore,both modeling and observational data show that the δ~(18)O_C records from southern China indeed reflect changes in precipitation δ~(18)O(δ~(18)O_P) rather than precipitation amount,and therefore that their use as an EASM proxy is inappropriate.Finally,we address several significant monsoon-related issues-including the driving mechanism of the EASM on an orbital timescale,the climatic significance of speleothem oxygen isotopes,and the relationship between atmospheric circulation and precipitation in monsoonal regions.     

Late Quaternary palaeosols in the Yangtze Delta, China, and their palaeoenvironmental implications

The stiff clays beneath Holocene strata in the Yangtze Delta are interpreted as palaeosols, based on pedogenic features including illuvial argillans, voids, cracks, iron–manganese concretions and nodules, and carbonate materials. Variations in clay content with depth, the occurrence of foraminifera, and the environmental magnetism characteristics of the palaeosols suggest that their parent materials are floodplain deposits. Anisotropy of magnetic susceptibility (AMS) parameters of the sediments correlate well both with sedimentary dynamics and depositional processes in different sedimentary environments, and AMS analysis may be a useful tool for inferring sedimentary environments. Based on their considerable thickness (> 3.0 m), vertical changes of palaeosol maturity, and occurrence of ageing argillans throughout the palaeosols, the palaeosols are inferred to be compound ones (pedocomplexes) resulting from alternating deposition and pedogenesis on the palaeointerfluve of the Yangtze River. Phytoliths in the palaeosols indicate that climates turned generally from warm and wet to cold and dry with marked fluctuations during development of the palaeosols. This suggests that the palaeosols developed mainly during the marine regression prior to the last glacial maximum. The vertical distribution of manganese materials (e.g., concretions, nodules, speckles and mottles) in the palaeosols suggests that the groundwater tables were about 2.0–3.0 m beneath the upper boundary of the palaeosols during their development. Yellow–brown streaks and speckles are abundant from the middle to lower parts of the palaeosols, and layers with high CaCO₃ content occur in the strata just beneath the palaeosols, but which lack caliche, suggesting that the groundwater table fluctuated markedly during their development. Voids and cracks filled with clays, and carbonate nodules (less than 0.1 mm in diameter) with thin iron–manganese rims are abundant in the palaeosols, indicating that wet and dry seasons were marked during the palaeosol development. It is suggested that the monsoonal influence was marked in the Yangtze Delta, with both winter and summer monsoons strongly developed during the development of the late Quaternary palaeosols.     

热动力条件对白云凹陷深水区珠海组砂岩成岩演化过程的影响

珠江口盆地白云凹陷位于中国南海北部,是目前我国深水油气勘探研究的重要区域.盆地现今大地热流值为24.2～121.0mW/m^2,单井现今地温梯度(Gra)最高可达6.64℃/100m,具"热盆"属性.白云凹陷裂后沉降阶段,特别是白云运动(23.8Ma)发生之后,盆地由断裂控盆转变为断裂、热作用共同控盆,热作用及热动力条件成为控制研究区储层成岩演化过程的重要因素,珠海组地层的镜质体反射率值、砂岩中次生流体包裹体均一温度、热液成因自生矿物等热流背景及岩石学记录为这一观点提供了有力证据.通过铸体薄片显微镜下观察与定量统计、电镜扫描观察、X-射线衍射分析等,发现白云凹陷北部中-低地温梯度(LGR,Gra≤4.5℃/100m)和南部高地温梯度(HGR,Gra>4.5℃/100m)两个地区珠海组砂岩的成岩作用特征、成岩演化过程存在以下差异:(1)中-低地温梯度地区珠海组砂岩的压实作用主要是静岩压实作用;高地温梯度地区珠海组砂岩的原生孔隙受静岩压实作用和热压实作用的共同控制,压实减孔速率高,等孔隙度埋深显著变浅;(2)地层升温速率的增大加快了储层中粘土矿物转化的速率,高地温梯度地区高岭石消失的埋深界限较中-低地温梯度地区浅,I/S(伊利石/蒙皂石混层)有序化进程较中-低地温梯度地区有所加快;(3)中-低地温梯度地区珠海组砂岩成岩演化过程属正常有序演变,高地温梯度地区受构造热事件的影响明显,深部流体参与了高地温梯度地区珠海组砂岩的成岩演化过程,地层孔隙水物质交换过程复杂,成岩演化进程加快,改变了碳酸盐矿物溶解-沉淀热平衡状态,各成岩作用过程活跃并出现一些典型的热液成因自生矿物组合.