Characterisation and preliminary quantification of the methane reservoir in a coastal sedimentary source: San Simón Bay,Ría de Vigo,NW Spain     

S. García-Gil  E. de Blas  N. Martínez-Carreño  J. Iglesias  R. Rial-Otero  J. Simal-Gándara  A.G. Judd 《Estuarine, Coastal and Shelf Science》2011

Ría de Vigo is a river valley flooded by the sea, with a bay (San Simón Bay) at its innermost part. The accumulation of Holocene sediment in San Simón Bay has been studied by the integration of 1) large scale high resolution seismic data, and 2) detailed geochemical analysis of a gravity core. In San Simón Bay the majority of the seismic records are obscured by acoustic turbidity which represents gassy sediments, but on records from Rande Strait it is possible to distinguish two Quaternary seismic sequences; an Upper Pleistocene sequence (SQ1) and a Holocene sequence (SQ2). Only SQ2 is recognized in San Simón Bay where it is comprised of two seismic units; the upper unit represents the HST sediment, i.e. the period of highest sea level. A gravity core taken within the gassy zone at 10 m water depth provided 3.55 m of fine-grained sediments (muds) from the youngest seismic unit (4 m thick). Geochemical analysis show high values (4 to 10%) of TOC. Sediment and porewater analyses indicate a distinct sulphate–methane transition zone (SMTZ) between 60 and 80 cm where sulphate is depleted (to <1.7 mM) and methane increases (to >0.4 mM). The top of the acoustic turbidity (the gas front) at 80 cm corresponds to the lower limit of the SMTZ. The methane cannot have been derived from the underlying metamorphic and granitic rocks, but was probably derived by microbial degradation of the organic matter in the Holocene sediments. We estimate that the sediments of the Bay contain approximately 1.8 × 10⁶ m³ of organic carbon and 275 ton of methane.  相似文献   

Chemosynthetic trophic support for the benthic community at an intertidal cold seep site at Mocha Island off central Chile     

Javier Sellanes  Germán Zapata-Hernández  Silvio Pantoja  Gerdhard L. Jessen 《Estuarine, Coastal and Shelf Science》2011

We analyzed C and N stable isotope ratios of benthic fauna and their potential food sources at an intertidal methane seep site and a control site without emanation at Mocha Island (central Chile). The objective was to trace the origin of the main food sources used by the local heterotrophic fauna, based on the hypothesis that chemosynthetic production could be partially fueling the local food web at the seep site. Food sources sampled at both sites included macroalgae, particulate organic matter and bacteria-like filaments found growing over the red algae Gelidium lingulatum within the areas of active methane release.  相似文献   

季风影响下的青藏高原上空甲烷、水汽及云的变化     

熊效振  张莹  陈良富  占瑞芬  李建平 《成都信息工程学院学报》2011,26(5):480-485

为进一步了解季风对于水汽及其它大气成分的输送作用,利用美国Aqua卫星上AIRS反演的甲烷（CH4）和MODIS反演的水汽、云高和云量等卫星观测资料,分析了2003至2010年中国青藏高原上空CH4、水汽和云在季风期间的变化及其与季风指数的关系。研究发现：夏季（6月至9月）高原上空水汽、云量和云顶高度的变化与季风指数有很好的相关;在强对流影响下,输送到高原上空的水汽增多,引起云量增多,云顶高度增加,而向上输送的甲烷引起高原上空CH4浓度增加,并在青藏高压强大的反气旋的阻塞下CH4不断积累,在季风期的后半程维持一个高值,但最大值出现在8月底至9月初,比季风指数的峰值晚近一个月。随着季风减退和青藏高压的消失,甲烷的高值快速消失。由此可见,夏季青藏高原的强对流输送无疑是甲烷高值形成的主要动力机制之一。cH4作为一种长寿命的温室气体,有潜力作为一种示踪气体来帮助研究季风和季风期间高原上空强大的反气旋动力机制的变化。  相似文献   

青藏高原多年冻土区沼泽草甸土壤CH_4产生速率研究   总被引：2，自引：1，他引：1  

赵拥华  杜二计  刘广岳  岳广阳 《冰川冻土》2011,33(5):999-1005

用实验室培养法对青藏高原多年冻土区沼泽草甸土壤不同温度条件下的CH4产生速率进行了研究.结果表明：CH4产生速率与温度之间呈现显著的指数关系,整个土壤剖面平均CH4生成速率和CH4生成速率初始值随温度的变化具有显著的相似性,都表现出随温度的升高而增加规律,0℃、5℃、18℃时的CH4生成速率分别是-18℃时的5.7、1...  相似文献   

利用AIRS产品分析中国地区近地面甲烷浓度时空特性   总被引：1，自引：0，他引：1  

王红梅  李佳田  张莹  李莘莘  张蓝  陈良富 《遥感学报》2015,19(5):827-835

甲烷(CH4)作为仅次于二氧化碳(CO2)的第二大温室气体,不仅在全球和区域尺度光化学反应中起着重要作用,而且在能量收支平衡及气候变化方面有着重要的影响。2013年,Auqa/EOS的大气红外探测仪(AIRS)热红外近地表CH4产品在AIRS Version6.0产品中发布,其结果尚未在中国进行验证,利用热红外传感器分析中国近地表CH4浓度的时空分布还处于初始阶段。本文利用中国青海瓦里关(WLG)、中国台湾鹿林山(LLN)及蒙古乌兰乌勒(UUM)地基观测资料对AIRS V6.0近地面CH4浓度产品进行了验证,误差在2%以内,二者相关系数r分别为0.68、0.5、0.69,变化趋势一致,进而从地域、季节变化和年际变化3个方面探讨了2003年—2013年中国地区近地面CH4浓度的时空分布特征。结果表明:CH4浓度最低值位于西藏地区(1800 ppbv),高值区位于新疆维吾尔自治区北部、内蒙古自治区及黑龙江北部(1920 ppbv);夏季高,冬季低,季节性变化明显,年际变化基本上呈增长趋势。  相似文献   

新疆阜康急斜地层煤层气井施工技术          下载免费PDF全文

石浩  姚宁平  赵洋洋  金新  张铁牛 《探矿工程》2015,42(10):17-20

针对新疆阜康白杨河煤层气矿区地层急斜、软硬互层、存在烧变岩层等问题造成的钻孔极易弯曲、坍塌等问题,采用空气潜孔锤钻井技术及无线电磁波随钻测井定向钻进技术,顺利解决了钻孔弯曲、塌孔、成孔难等施工难题,施工效率达到常规钻井速度的3倍以上,对于类似地层的煤层气井施工有借鉴意义。  相似文献   

Coalbed Methane Enrichment Regularity and Major Control Factors in the Xishanyao Formation in the Western Part of the Southern Junggar Basin     

YUAN Yuan  SHAN Yansheng  TANG Yue  CAO Daiyong 《《地质学报》英文版》2020,94(2):485-500

There are abundant coal and coalbed methane(CBM)resources in the Xishanyao Formation in the western region of the southern Junggar Basin,and the prospects for CBM exploration and development are promising.To promote the exploration and development of the CBM resources of the Xishanyao Formation in this area,we studied previous coalfield survey data and CBM geological exploration data.Then,we analyzed the relationships between the gas content and methane concentration vs.coal seam thickness,burial depth,coal reservoir physical characteristics,hydrogeological conditions,and roof and floor lithology.In addition,we briefly discuss the main factors influencing CBM accumulation.First,we found that the coal strata of the Xishanyao Formation in the study area are relatively simple in structure,and the coal seam has a large thickness and burial depth,as well as moderately good roof and floor conditions.The hydrogeological conditions and coal reservoir physical characteristics are also conducive to the enrichment and a high yield of CBM.We believe that the preservation of CBM resources in the study area is mainly controlled by the structure,burial depth,and hydrogeological conditions.Furthermore,on the basis of the above results,the coal seam of the Xishanyao Formation in the synclinal shaft and buried at depths of 700-1000 m should be the first considered for development.  相似文献   

Flooding of the continental shelves as a contributor to deglacial CH4 rise     

Andy Ridgwell  Mark Maslin  Jed O. Kaplan 《第四纪科学杂志》2012,27(8):800-806

The transition from the last glacial and beginning of Bølling–Allerød and Pre‐Boreal periods in particular is marked by rapid increases in atmospheric methane (CH₄) concentrations. The CH₄ concentrations reached during these intervals, ～650–750 ppb, is twice that at the last glacial maximum and is not exceeded until the onset of industrialization at the end of the Holocene. Periods of rapid sea‐level rise as the Last Glacial Maximum ice sheets retreated and associated with ‘melt‐water pulses’ appear to coincide with the onset of elevated concentrations of CH₄, suggestive of a potential causative link. Here we identify and outline a mechanism involving the flooding of the continental shelves that were exposed and vegetated during the glacial sea‐level low stand and that can help account for some of these observations. Specifically, we hypothesize that waterlogging (and later, flooding) of large tracts of forest and savanna in the Tropics and Subtropics during the deglacial transition and early Holocene would have resulted in rapid anaerobic decomposition of standing biomass and emission of methane to the atmosphere. This novel mechanism, akin to the consequences of filling new hydroelectric reservoirs, provides a mechanistic explanation for the apparent synchronicity between rate of sea‐level rise and occurrence of elevated concentrations of ice core CH₄. However, shelf flooding and the creation of transient wetlands are unlikely to explain more than ～60 ppb of the increase in atmospheric CH₄ during the deglacial transition, requiring additional mechanisms to explain the bulk of the glacial to interglacial increase. Similarly, this mechanism has the potential also to play some role in the rapid changes in atmospheric methane associated with the Dansgaard–Oeschger cycles. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Poor fen succession over ombrotrophic peat related to late Holocene increased surface wetness in subarctic Quebec,Canada     

MICHELLE GARNEAU  ALEXANDRE LAMARRE  ÉLISABETH C. ROBERT  GABRIEL MAGNAN  HANS ASNONG  STEVE PRATTE 《第四纪科学杂志》2013,28(8):748-760

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Extension of the Paraná Basin to offshore Brazil: Implications for coalbed methane evaluation     

Michael Holz  Wolfgang Kalkreuth  Silvia Beatriz Alves Rolim 《Marine and Petroleum Geology》2010

Coalbed methane (CBM) is a worldwide exploration target of the petroleum industry. In Brazil, the most important coal-bearing succession is associated with the Permian Rio Bonito Formation of the Paraná Basin. The gas-prone areas are located at the southeastern margin of the Paraná Basin and possibly in the offshore region of the northern part of the Pelotas Basin. Coalfields end abruptly at the present day shoreline, a result of rifting of Gondwana and the evolution of the South Atlantic Ocean. All geologic indicators suggest that in pre-rift times the coal seams extended further eastwards, probably now lying deeply buried below the sedimentary succession of the Pelotas Basin. The present paper discusses structural, stratigraphic, seismic and aeromagenetic data that support the preservation of continental crust beneath ocean sediment. If the coal beds had similar lateral extent to known onshore coals, and coal beds extended across the projected extension of the Parana basin, and there was a conservative 5 m of cumulative coal thickness, then a potential methane volume can be estimated for this newly inferred resource. Average onshore coal gas content is 32 scf/ton (1.00 m³/ton). If this is similar in the offshore coal deposits, then the hypothetical methane volume in the offshore area could be in excess of 1.9 × 10¹² scf (56 × 10⁹ m³). Metamorphism from dikes associated with rifting are potential complicating factors in these deposits, and since no borehole reaching the deep-lying strata in the offshore area are available, this is a hypothetical gas resource with a certain level of uncertainty which should be tested in the future by drilling a deep borehole.  相似文献