基于中国羌塘盆地、祁连山、漠河盆地冻土区浅表土壤样品资料,进行了烃类气体组分地球化学特征、成因及性质分析.结果表明,冻土区浅表烃类气体主要成分为甲烷,还含有少量乙烷、乙烯、丙烷、丙烯、丁烷和戊烷.羌塘盆地和漠河盆地烃类气体主要为热解成因,气体类型为油型气及其与煤层气的混合气;祁连山冻土区浅表土壤中烃类气体具有热解成因和生物成因,气体类型包括油型气、煤层气和生物气.烃类地球化学调查为我国陆域冻土区水合物等油气资源勘查提供了依据.

为了发挥油气化探"迅速掌握全局快速缩小靶区"的战略性作用,服务油气化探全国扫面计划,选择塔里木含油气盆地北部开展低密度(1点/25 km2)油气地球化学填图试点.油气化探填图指标土壤酸解烃、顶空气轻烃、荧光光谱、紫外吸收光谱和蚀变碳酸盐在大型油气田、油气富集区带上方均发育地球化学省异常,异常平面空间分布与地下油气富集区带具有良好的套合关系,对油气富集具有指示意义.区域性的荧光光谱等指标异常浓集中心沿轮台断裂等主干断裂带分布,与地下断裂位置良好的匹配性指示了油气大规模的运聚.甲烷碳同位素证实研究区油气地球化学省异常成因为热解成因,土壤样品三维荧光光谱发育共性峰,三维荧光光谱指纹特征反映了近地表土壤烃类异常与地下油气运移和油气藏类型相关.塔里木盆地北部地区油气地球化学填图试点结果表明,大型盆地可以采用甚低密度油气地球化学填图技术,圈出寻找大、中型油气田和油气富集区带的异常区,发挥油气化探"迅速掌握全局快速缩小靶区"的战略性作用.

为探索顶空气轻烃技术在陆域冻土区天然气水合物地球化学勘查中的应用,选择祁连山木里已知天然气水合物矿区和哈拉湖未知区作为方法技术的试验区.试验指标包括土壤顶空气、土壤酸解烃、岩芯顶空气轻烃测井、甲烷碳同位素.研究表明:祁连山木里已知天然气水合物矿藏上方,土壤顶空气轻烃组分以甲烷为主,甲烷所占比例非常高,90.6％的样品C1含量都在78％以上,甲烷含量显著高于常规油气盆地;未发现天然气水合物的哈拉湖试验区,无明显的土壤顶空气轻烃异常现象.顶空气轻烃异常模式为:平面上,矿藏上方近地表土壤中存在明显的顶空气甲烷强异常;剖面上,在天然气水合物稳定带上方呈现"前缘晕"异常特征;其空间分布与祁连山水合物矿藏展布空间具有套合关系.甲烷碳同位素和烃类组成判断地表油气化探异常为热解成因,与祁连山冻土区天然气水合物的气体为同一成因来源.陆域冻土区天然气水合物顶空气轻烃地球化学勘查技术试验结果表明:顶空气轻烃地球化学方法既可以判断水合物成因类型,也可以圈出水合物矿藏范围.

我国多年冻土区多位于中纬度高原地区,与环北冰洋极地地区多年冻土的状态不完全相同,天然气水合物成因机理、赋存环境和基本特征更为复杂.近10年来,在自然资源部行业专项和中国地质调查局水合物试采专项的资助下,先后在青藏高原和东北多年冻土区开展了天然气水合物地球化学勘探技术攻关,总结了多年冻土区天然气水合物地球化学指标组合和识别标志,探讨了多年冻土区天然气水合物地球化学成藏机制,研发了多年冻土区天然气水合物地球化学勘查模型,初步建立了多年冻土区天然气水合物调查地球化学方法技术体系,在勘探实践中发挥了重要的作用,地球化学方法技术对天然气水合物的有效性得到了初步检验和应用,具有广阔的应用前景.

In this study, systematic soil methane cycle geochemical monitoring was carried out in a typical gas hydrate region in the Qinghai-Tibet Plateau. Soil gas samples were collected for hydrocarbon components and carbon isotope analysis. Meanwhile, soil-methane fluxes from the upper active layer (20–30 cm) were monitored during six months of one year. The results of this research provide evidence of a new source of methane emission from wetland soils in permafrost regions: gas hydrate release. Sites with large methane emissions were found using flux monitoring, the characteristics of thermogenic methane were identified using carbon isotope tracing, and the relationship between emission by soils and effusion from gas hydrates was determined through correlation analyses of soil-adsorbed hydrocarbons. Seasonal variation of methane emissions are also discussed by considering the emission of bacterial methane, thermogenic methane, and the absorption of methane from the soil active layer. These comprehensive findings provide valuable information for carbon cycle research of wetlands in permafrost regions.

祁连山哈拉湖坳陷与已发现天然气水合物的木里坳陷同属于南祁连盆地次级坳陷,有相似的水合物成藏条件,但由于该区地质工作程度低,坳陷内第四系覆盖层下的地质构造信息不清,对该区的天然气水合物成藏条件缺乏认识.为查明哈拉湖坳陷的地质构造特征和天然气水合物成藏条件,在哈拉湖坳陷区内开展了物化探综合探测及研究,结果表明:(1)调查区内可划分出4个凹陷区、2个凸起区,调查区内可划分出26条断裂;(2)调查区永冻土层分布特征以新生界沉积区以大面积片状和基岩出露区以岛状分布为主,永冻土层发育与高程、地形、地表覆盖层及表层土壤水分等因素密切相关;(3)调查区发现了两处地球化学异常,以酸解烃重烃、酸解烃干燥系数、顶空气甲烷和荧光光谱为指标组合,显示了两种不同的异常特征类型,异常浓集中心明显,强度较高;(4)哈拉湖坳陷的烃原岩条件相对差,烃源岩的保存完整性和印支—燕山期圈闭构造是水合物成藏的关键,哈拉湖坳陷区北部和地球化学Ⅰ号异常区可为水合物成藏远景区.本文为南祁连盆地下一步天然气水合物资源调查与评价提供了依据.

陆域冻土区天然气水合物成矿机制较为复杂,水合物横向难以对比,形成机理不清楚,急需对天然气水合物迁移机理进行研究.文章根据祁连山冻土区天然气水合物发现区钻井揭示的地质和地球化学资料以及岩芯样品分析测试结果进行了综合分析.结果显示,研究区中侏罗统和上三叠统均为较好烃源岩,天然水合物气源以热解气为主,主要由上三叠烃源岩迁移和中侏罗统木里组烃源岩扩散提供,显示了多源多期次的特点.根据地质和地球化学分析,祁连山天然气水合物的形成经历了晚侏罗世—早白垩世的气体运移与聚集、中新世中晚期—上新世整体抬升、第四纪游离气体转化成天然气水合物矿藏3个阶段,经历了"先聚集-再抬升-后成藏"等过程,是构造-气候耦合作用的结果,初步建立了祁连山冻土区天然气水合物迁移机理.

At present, the optimization of the optimal thermal recovery temperature in the process of thermal natural gas hydrate is considered from the aspects of reducing the heat injection and increasing the heat of combustion of the gas, that is, the combustion of methane gas under the unit heat injection. The thermal recovery temperature corresponding to the maximum heat is the optimal thermal recovery temperature. Based on the consideration of reducing the heat loss in the thermal recovery process, this paper considers the reduction of the duration of the thermal recovery process, introduces the new concept of thermal recovery development efficiency, and defines the thermal recovery development efficiency as the unit heat injection in the natural gas hydrate thermal recovery process. The combustion heat of the average gas production rate is introduced into the concept of an infinitely long cylindrical heat exchange reaction kettle. The 303K, 318K, 333K, 348K and 353K partition wall thermal gas hydrate experiments are carried out for the own equipment. The experimental data show that 348K degrees C can be obtained. The largest thermal development efficiency. Using the thermal development efficiency evaluation standard of this paper, for the weather hydrate thermal recovery process under different parameters, by determining the optimal heat exchange temperature, the energy utilization efficiency and gas production rate of the thermal recovery process can be significantly improved, and the thermal recovery development can be reduced. Economic costs in natural gas hydrate processes.

开发地球化学勘查新技术是提高中纬度冻土区天然气水合物探井预测成功率的重要课题之一.本文选择在祁连山聚乎更天然气水合物已知区进行土壤热释汞勘查技术试验,试验区为高寒沼泽景观,面积150 km2,采样密度2点/km2,采样深度60 cm,采集土壤样品300件,应用测汞仪对土壤样品进行了热释汞分析.试验结果表明,土壤热释汞在天然气水合物矿藏边界出现高值异常,在天然气水合物上方是低值带,与烃类异常浓度范围一致,为串珠状异常模式,热释汞最大值为127.37×10-9,平均值为32.59×10-9,异常下限为39.24×10-9.结合地质和地球化学勘查成果进行了综合解释,认为祁连山聚乎更地区热释汞异常与天然气水合物矿藏关系密切,源于深部水合物矿藏,对天然气水合物进一步调查具有重要的参考价值.

根据祁连山木里地区已知天然气水合物上方不同期次近地表土壤地球化学勘查重复性试验,对土壤酸解烃、顶空气、荧光光谱、碳酸盐等指标方法的稳定性及异常重现性问题进行研究和探讨.结果表明,各项化探指标不同期次含量最大值等特征值虽然存在一定程度的差异,但是其数据波动特征和数据结构是相对一致的.顶空气甲烷、酸解烃、荧光光谱和碳酸盐方法指标前后两次测量结果均具有较高的相关性,配对T-检验显示顶空气轻烃、酸解烃和碳酸盐指标数据变化差异不显著,从统计学上看其指标数据具有较好的稳定性.顶空气甲烷、酸解烃、荧光光谱等指标地球化学异常在研究区已知天然气水合物矿区上方具有相似的空间分布特征,说明其化探指标异常空间上具有良好的稳定性和重现性;但是顶空气重烃异常模式、碳酸盐异常强度的变化,反映其具有重现性,但异常稳定性相对较差.这为地球化学勘查在陆域冻土区天然气水合物勘查中发挥作用提供了较好的基础.

为了研究战略性油气地球化学填图技术,选择松辽盆地进行了试点研究.填图面积12万平方公里,填图比例尺1:25万,采样密度1点/25平方公里,分析了土壤酸解烃、顶空间轻烃、K-V指纹、紫外吸收光谱、荧光光谱和微量元素等.松辽盆地油气地球化学图集包含五部分,分别是松辽盆地地理信息、油气地球化学图、油气地球化学异常图、油气资源潜力分形-GIS预测图和编制说明.松辽盆地油气地球化学填图结果表明:大型盆地可以用超低密度进行地球化学填图,圈出了地球化学巨省套合地球化学省的模式,圈出了新的油气战略远景区.松辽盆地油气地球化学填图成果为大型盆地战略性油气勘查提供了成功示范.

开发不受沼泽微生物影响的地球化学勘查技术是提高中纬度冻土区天然气水合物探井预测成功率的重要课题之一.本文选择在祁连山聚乎更天然气水合物已知区进行惰性气体勘查技术实验,研究了氦氖的测试方法,实验区为高寒沼泽景观,面积150km2,采样密度2点/km2,采样深度60cm,采集土壤顶空气样品300件和DK-3井岩芯样品400件,应用色谱反吹技术对顶空气样品进行了惰性气体氦氖的分析.结合地质和地球化学勘查成果进行了综合解释,认为惰性气体异常与天然气水合物矿藏关系密切,与烃类异常浓度范围一致,为顶部异常模式.实验区天然气水合物矿藏11个水合物发现井有10个位于He、Ne异常内,1个井位于异常外.分析了天然气水合物岩芯顶空气轻烃和氦氖指标的垂向分布特征,提出了天然气水合物矿藏上方土壤惰性气体的地气迁移机理.研究区近地表氦氖异常源于深部水合物矿藏和断裂构造,不受沼泽微生物的影响,是冻土区天然气水合物勘查的一种有效技术.

稀有气体氦(He)、氖(Ne)是天然气水合物中的痕量组分,其化学性质稳定,在地质作用过程中其丰度变化几乎不受复杂化学反应和近地表微生物的影响.顶空气He、Ne地球化学勘查方法可以排除沼泽区微生物的强烈干扰,提高包括天然气水合物在内的油气近地表地球化学勘查的效用及精度.选择祁连山木里冻土区天然气水合物矿区进行试验研究,获得近地表土壤顶空气He平均含量为7.99×10-6,Ne平均含量20.8×10-6,均高于其在大气中的丰度.稀有气体He、Ne具有很强的穿透能力,平面上,在已知水合物矿藏和水合物远景区上方具有明显的地球化学顶部异常特征;钻井地球化学垂向剖面上,水合物富集层位上方具有明显的上置气异常特征.顶空气He、Ne近地表平面异常和钻井岩屑剖面异常特征证实,祁连山水合物形成过程中烃类气体发生了分异和垂向微渗漏,其携带笼中的稀有气体He、Ne以“类气相”地气流形式垂向迁移.试验证明,顶空气He、Ne异常对木里天然气水合物矿藏具有良好的指示作用.顶空气He、Ne勘查方法是冻土区水合物地球化学勘查技术的有效补充.

1.Objectives As the discovery of gas hydrate in Qilian Mountain permafrost in 2008,the main controlling factors and distribution of gas hydrate are not clear.This restricts the further progress in gas hydrate survey in this area.Hence,

漠河盆地是我国冻土发育的主要地区之一,发育良好的天然气水合物成藏系统,具有天然气水合物形成的良好条件.为了圈定天然气水合物远景区,识别油气聚集体,判别天然气水合物成因,在漠河盆地冻土较发育地区开展了1∶5万天然气水合物地球化学资源调查.结果表明:(1)在森林沼泽景观区,顶空气和荧光光谱指标是天然气水合物勘查的主要指标,借鉴青海木里冻土区天然气水合物地球化学勘查成功的经验,结合AMT、地质等资料分析,元宝山凹陷是天然气水合物较为有利的远景区;(2)岩心样品甲烷碳同位素分析显示,烃类气体分异明显,浅层烃类气体基本为生物气,深部烃类气源主要为混合成因气,个别解吸气为微生物气和热解气;(3)试验性应用了分形-GIS技术,可以细致可靠地进行异常区范围划定,消除干扰因素,有效地圈定水合物远景区.

The permafrost regions of the Tibetan Plateau are distributed in the middle latitudes of China,where the gas hydrate is differ ent from the gas hydrate in sea area and polar permafrost area in existing environment and basic characteristics.The lack of effective exploration technology has become the major technical bottleneck that restricts the investigation and evaluation of natural gas hydrate resources in permafrost regions of China.Supported by National 863 Program,Special Research Project of Ministry of Land and Resources and National Special Project of Gas Hydrate,the authors studied the development of key technologies of natural gas hydrate exploration in the permafrost regions of China.The prorate exploration methods for China's terrestrial gas hydrate exploration in permafrost areas have been initially established,which include the high resolution seismic method,the audio magnetotelluric sounding technology,the ultra-deep ground penetrating radar (GPR) technology,geochemical exploration technology and integrated geophysical logging technology.The seismology and electromagnetism identifications of gas hydrate reservoir have been found,the effective index of hydrate geochemical exploration is optimized,and the logging identification technology and reservoir parameter evaluation technology of gas hydrate reservoir are developed.An effective combination method for geophysical and geochemical exploration and a comprehensive geophysical and geochemical exploration model have been tentatively established in permafrost regions.The favorable area of gas hydrate accumulation is predicted,and several gas hydrate reservoirs have been found in the well suggested by the authors,which shows that the validity of methods proposed by the authors are tentatively tested and applied.The research results have great significance for promoting the progress of gas hydrate exploration and for supporting the exploration and development of natural gas hydrate resources in permafrost regions of China.

Gas hydrate in Sanlutian area of Qilian Mountain is different from that of marine gas hydrate,and hence it is very urgent to study geosicience and exploration model.According to the theory of petroleum system and the achievements of geology,geography,geochemistry and drilling,the authors created a four-in-one geological model for gas hydrate deposit.Based on the summary of geophysical and geochemical exploration in recent years,the authors further established a model of gas hydrate exploration in permafrost region.Various geochemical indicators show top anomaly,annular anomaly and negative anomaly.Continuous distribution of high resistance was detected by audio magnetotelluric survey (AMT),the feature of ground penetrating radar is high-speed electromagnetic wave,slow attenuation and obvious reflected signal along bottom boundary of permafrost.The seismic indicators of ore-controlling fault find expression in such phenomena as faulting,termination,distortion,mutation or bifurcation in accordant axis of reflection wave,and the feature of AMT is electrical discontinuity.The reflected signal in gas hydrate bed is low velocity,high frequency and weak amplitude.The logging response is high resistivity,low acoustic time,low natural gamma and low density.

The field measuring test of free-gas methane was carried out in Muli known hydrate region of Qinghai through west portable soil flux measuring instrument and G2132-iAnalyzer Methane-carbon isotope analyzer.The spatial distribution of free-gas methane characteristic values and geochemical anomaly reveals that there exist good free-gas methane geochemical anomalies above the hydrate deposit,while the spatial distribution of the anomalies is controlled by ore-controlling fractures and underground mineral resources,show ing corresponding relation.The research on organic geochemistry and carbon isotope indicates that the gas hydrates in Qilian permafrost region is of thermal origin.The free-gas methane field analysis shows that the free-gas methane geochemical anomaly is mainly of thermal and microorganism origin,and the free-gas methane experiment in winter can reduce the interference of the surface microbial action.The study results indicates that the free-gas methane field measuring technique is applicable to the natural gas hydrate exploration,which can not only indicate the hydrate deposits but also serve as the mutual supplement to other hydrates geochemical exploration techniques,with the best sampling time being winter.

Wetland is an important part of global carbon cycle.As the largest wetland in China,the Tibetan Plateau is a hotspot in the research on wetland carbon cycle.In this paper,the authors evaluated the effect of gas hydrate exploration on wetland carbon cycle in Muli Basin,Qilian Mountain,the Tibetan Plateau.By using geochemical methods such as top gas and acidolysis hydrocarbon,the au thors measured the values of the acidolysis hydrocarbon in 2009,2011,2013,which were 15.55 μL/kg,13.73 μL/kg,and 12.82 μL/kg respectively,with no significant increase.The top gas in 2009,2011,2013 were 4.49 μL/L,6.16 μL/L,and 19.22 μL/L respectively,showing increasing trend.The distribution characteristics analysis shows that top gas has short time efficiency,and can not be used to indicate the increase of hydrocarbon gas.The results show that the effect of gas hydrate wells has the features of wide range and low strength on regional carbon cycle system.The environment impact is less and in the controllable range.

As an important part of the earth's terrestrial carbon cycle,the Tibetan Plateau has become a hot place of warmhouse gas emission.The effect of gas hydrate exploration on ecological environment deserves much attention.In this paper,the authors studied the flux and isotope of subsurface methane in gas hydrate area of the Qilian Mountain.Some conclusions have been reached:1.Methane emission from alpine steppe and alpine meadow shows seasonal features.The maximum emission value is 19.2 mg/m2 · h and the maximum absorption value is-108 mg/m2 · h,demonstrating the role of carbon sink.2.Methane isotope data show that there exist a large number of microorganisms in the active layer of permafrost region.The methane in 10 ～ 30cm is the cause of microorganism,which is relatively active in summer and inactive in winner.The metabolic process of microorganism changes the oxidation-reduction of methane,and bacteria addicted to methane leads to the emission of methane.3.As for the occurrence state of gas hydrate and the way of exploration,the phenomenon of blast increase of methane in near-surface atmosphere does not appear.4.The emission of methane is influenced by many factors,and hence the study of temperature,moisture and PH value of soil needs further research.