Discovery of Mass Independent Oxygen Isotopic Compositions in Superscale Nitrate Mineral Deposits from Turpan-Hami Basin,Xinjiang,China and Its Significance

The Turpan-Hami Basin in eastern Xinjiang is one of the driest regions on Earth and a premier environment to form and preserve nitrate.A large nitrate ore field in this basin was found recently.It is estimated there are about 2.5 billion tons of resources of nitrate,and the amount is as much as the Atacama Desert super-scale nitrate deposit in Chile.Nitrate is one of a few minerals with mass-independent fractionation（MIF）,and the oxygen isotope MIF is an effective method to determine the source of nitrate.Theδ^（17）O,δ^（18）O of nitrate were measured by fluorination and thermal decomposition method.The date indicated that this is the first time that oxygen isotope MIF has been located in inland nitrate minerals.The results obtained by two methods are similar,⊿^（17）=δ^（17）O-0.52×δ^（18）O=12‰-17‰.The experiment and observation data proved that oxygen isotope MIF of nitrate are the result of photochemical reactions in the troposphere and stratosphere.Thus, evidence from MIF oxygen isotopic compositions indicate that long term atmospheric deposition of nitrate aerosol particles produced by photochemical reactions is the source of the deposits.

Types of Organic Fades and Source Rock Assessment of the Coal-Measure Mudstone in the Turpan-Hami Basin

This paper discusses the enviromental characteristics of carbonaceous mudstone and mudstone (coal-measure mudstone in short) of the Early and Middle Jurassic in the Turpan-Hami basin, which were formed in swamps. Through the organic facies study of the coal-measure mudstone in this area, the authors clarify that the flowing-water swamp is the most advanced organic facies belt. Furthermore, according to the practical materials of coal-measure mudstone in the area and with the evaluation criteria of lacustrine mudstone in the past, the authors have established the integrated symbol systems from the abundance of organic matter and the type of organic matter, which can be used in the source rock evaluation of the coal-measure mudstone.

The Characteristics and Genesis of the Massive Nitrate Deposits in the Turpan-Hami Basin of Xinjiang,China

Massive nitrate deposits have been discovered in the Turpan-Hami basin in northwestern China.Previously,large ore grade nitrate minerals were thought only to exist in the Atacama Desert in northern Chile.Estimates of the

Oil accumulation related to migration of source kitchens in the Lukeqin structural belt, Turpan-Hami Basin, China

The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.

Early and Middle JurassicPalaeogeography of the Turpan-Hami Basin

The Turpan-Hami oil basin is well known for its Jurassic oil-prone coal. The palaeogeograpbical units or the Early and Middle Jurassic coal measures iuclude braided chaunel-alluvial plain, meandering channel-alluvial plain, upper delta plain, lower delta plain, subaqueous delta, inter-deltaic bay,lacustrine bay and sballow lake euvironments. The beneficial environments for coal accumulation were tke inter-delta bay and the lower delta plain where intermediate subsidence was maintaiued and there was little input of coarse graiued ediments.

Provenance Variability of the Triassic Strata in the TurpanHami Basin: Detrital Zircon Record of Indosinian Tectonic Reactivation in the Eastern Tianshan

The Triassic strata in the Turpan-Hami Basin potentially chronicled the missing sedimentary record of Indosinian tectonic evolution in the Eastern Tianshan.In this study,we conducted detrital zircon U-Pb geochronological analyses on subsurface Triassic samples collected from the Turpan-Hami Basin to unravel sedimentary response of Indosinian tectonic reactivation and its geodynamics.The detrital zircon age spectra of the Triassic samples are quite different,reflecting significant provenance variability.The zircon grains in the Lower Triassic sample were mainly from the Central Tianshan,while the Jueluotag acted as a minor provenance.By contrast,the Late Paleozoic rocks in Jueluotag act as the main provenance for the Middle-Upper Triassic samples,while the Central Tianshan acted as a minor provenance.Furthermore,zircon grains in the Middle Triassic sample were mainly from the Permian rocks in Jueluotag,while Indosinian strike-slipdriven rapid exhumation brought deeper Carboniferous rocks of Jueluotag as an important age population for the Upper Triassic sample.The inter-sample variability of age spectra of the Triassic samples provides sedimentary evidence for Indosinian tectonic reactivation in the Eastern Tianshan and its periphery,which could be attributed to differential exhumation of different sources driven by coeval strike-slip tectonics along deep faults.The Indosinian tectonic behavior in the Eastern Tianshan,which is characterized by partial melting of the pre-thickened crust and strike-slip deformation,acted as a far-field respond to the coeval continental accretion occurring along the southern Eurasian margin.Additionally,our new detrital zircon data,together with previously published data in the Turpan-Hami Basin,demonstrate that there are significant changes in source-to-sink system from the Permian to the Triassic,suggesting that the Permian-Triassic unconformity in the Eastern Tianshan and its periphery was generated by Late Permian-Early Triassic tectonic contraction and inversion rather than an increasingly arid climate.

Sequence Stratigraphy and Paleogeography of the Early and Early Middle Jurassic Coal Measures in the Turpan-Hami Basin,Northwestern China

This paper analyses the sequence stratigraphy and palaeogeography of the Early and early Middle Jurassic coal measures in the Turpan-Hami Basin, northwestern China.The controls of the palaeogeography and sequence stratigraphy on the coal accumulation in this basin have been discussed.The results show that the coal measures were formed in a fluvial-delta-lacustrine sedimentary system,and a total of 4 third-order sequences were developed,

Stable carbon and hydrogen isotopic characteristics of natural gas from Taibei sag, Turpan-Hami Basin, NW China

Turpan-Hami Basin is a major petroliferous basin in China. To date the natural gas exploration is concentrated in the Taibei sag. The origin and source of natural gas in the Taibei sag has long been controversial. To further investigate the origin and source of the natural gas in the Taibei sag, combined with previous studies and the local geological backgrounds, this study collected 23 gas samples from the Baka, Qiuling, Shanshan and Wenmi oil fields in the Taibei sag and analyzed the sample composition, stable carbon and hydrogen isotopes of all the gas samples. The results show that, gases from the four oil fields in the Taibei sag are dominated by hydrocarbon gas and belong to wet gas. Methane accounts for 65.84% to 97.94%, the content of heavy hydrocarbon (C2-5) can be up to 34.98%, while the content of nonhydrocarbon (CO2, N2) is trace. The δ13C1 value is –44.9‰ to –40.4‰,δ13C2 is –28.2‰ to –24.9‰,δ13C3 is –27.1‰ to –18.0‰ and δ13C4 is –26.7‰ to –22.1;while the variation of δD1 is not significant from –272‰ to –252‰,δD2 is –236‰ to –200‰ and δD3 is –222‰ to –174‰. Methane and its homologues (C2-5) are characterized by normal stable carbon and hydrogen isotopic distribution pattern, i.e., with the increase of carbon number, methane and its homologues become more and more enriched in 13C or D (δ13C1<δ13C2<δ13C3<δ13C4<δ13C5,δD1<δD2<δD3), which is consistent with the carbon and hydrogen isotopic features of typical thermogenic gas. All these results show that the natural gases in the four oil fields are coal-derived gas with low maturity (Ro averaged at 0.7%), and are sourced from the Middle-Lower Jurassic coal measure. The hydrogen isotopic data of natural gas are affected by both thermal maturity and the water medium of the environment where source rocks are formed. The hydrogen isotopic data indicate that the source rocks are formed in terrestrial limnetic facies with freshwater. Natural gases from Well Ba23 and Well Ke19 experienced biodegradation in the late stage.

吐哈盆地台北凹陷中侏罗统西山窑组深层煤岩气地质特征与勘探潜力

深层煤岩气是吐哈盆地油气勘探的新领域,但研究程度相对较低。基于煤岩测试与基础资料,系统研究了吐哈盆地台北凹陷中侏罗统西山窑组煤层分布、煤岩煤质、储层物性、宏微观煤岩、煤储层气源及煤岩等温吸附特征,揭示了煤岩储层含气性及其影响因素,提出了深层煤岩气形成富集条件,建立了深层煤岩气富集成藏模式,预测了台北凹陷煤岩气勘探潜力。结果表明:(1)台北凹陷深层侏罗系西山窑组煤层分布广、厚度大,为中低阶、原生结构、割理发育的低灰、低水、富镜质组煤层;(2)煤储层孔渗较高且受埋深影响不明显,煤层段气测异常普遍且储层吸附性能中等—好,具有游离气与吸附气共存、试采快速见气、气组分齐全等特征;(3)台北凹陷煤岩气的油气供给充注,可以形成正向构造带“调整型”和斜坡及洼陷区“自生自储型”两种成藏模式;(4)台北凹陷煤岩气资源丰富,西山窑组主煤层煤岩气资源量近3×10^(12)m^(3)。根据煤岩气资源丰度、煤层厚度、含气量、保存条件等综合评价优选出温吉桑构造带、小草湖南斜坡为深层煤岩气勘探有利目标区。

基于PLUS-InVEST模型吐哈盆地陆地生态系统碳储量时空变化及多情景模拟

土地覆盖变化能够改变区域碳储存能力,从而引起全球气候变化。研究土地覆盖变化对碳储量的影响,预测未来不同土地覆盖情景下的碳储量,对实现区域“碳中和”战略目标具有重要意义,然而目前针对中国西部生态脆弱区的研究仍有待探究。以新疆吐哈盆地为研究区,基于土地覆盖产品数据,结合PLUS模型和InVEST模型,探讨了土地覆盖变化与区域碳储量的时空变化关系,预测和评估了2025、2030年可持续发展情景,维持现状发展情景,经济优先发展情景下土地覆盖和碳储量的时空动态特征。结果表明:(1)近20 a来,吐哈盆地耕地和裸土地面积增加最大,其次是建设用地,而草地表现出最大的减少趋势,草地转为耕地和建设用地是最主要的转移类型。(2)2000、2010年和2020年吐哈盆地平均碳储量分别为26.01 t·hm~(-2)、25.68 t·hm~(-2)、25.73 t·hm~(-2),呈现出先降低后增加的趋势,平均碳储量累计减少了0.28 t·hm~(-2),其中土壤有机质碳储量占比最高,约占总碳储量的94%,裸土地、草地贡献了最多的碳储量。(3)2030年3种情景下,森林、灌木林、湿地几乎无明显变化,裸土地呈现出减少的趋势,而建设用地呈现增加的趋势。(4)到2030年可持续发展情景下吐哈盆地总碳储量较2020年增加了0.18×10~6t,维持现状发展情景和经济优先发展情景下分别减少了0.30×10~6t、1.01×10~6t,经济优先发展情景下碳储量损失最大。研究结果可为吐哈盆地土地利用优化以及制定生态系统可持续发展措施提供依据。

深层煤层气水平井安全钻井技术

针对吐哈盆地深层煤层气的勘探,前期以直井试采为主,水平井的钻井技术仍处于探索阶段。由于该区块属于高陡斜坡区、煤系地层发育,导致直井段井斜易超标、煤系地层的井眼井壁易失稳、水平井井段的轨迹难以控制及固井质量差等问题,文章通过分析高陡斜坡区提速限制因素,引入自动垂钻系统,形成直井段防斜打快技术,解决了高陡斜坡区防斜和大钻压快速钻进的矛盾;分析煤层井壁失稳机理,开展浸泡实验,优选了胺基有机盐钻井液体系,提高抑制性和封堵固结井壁性能,强化了煤系地层井壁稳定;结合深层煤层三压力剖面预测数据优化井身结构及轨迹控制,设计防卡PDC钻头和钻具组合,配套强抑制、强封堵性胺基有机盐钻井液,实现了煤层水平段安全延伸;强化钻井参数,应用岩屑清洁工具和个性化通井钻具组合,提高了井眼清洁效率;优化套管选型、扶正器配置及水泥浆体系,保障了固井质量。该系列技术为实现吐哈盆地深层煤层气水平井安全高效钻探奠定了基础。

Geochemical characteristics of light hydrocarbons in natural gases from the Turpan-Hami Basin and identification of low-mature gas

Theoretical and practical knowledge regarding low-mature gasses is of significant importance to identifying potential natural gas resources.Light hydrocarbon parameters and C and H isotopes are useful tools to identify low-mature gas.Twenty gas samples were collected from the Turpan-Hami Basin for light hydrocarbon analyses.The results showed that the light hydrocarbon components of natural gases contain high methylcycloxane,high isoparaffin and low benzene.This implies that the gas-generating parent materials are of typical humus type and the paleoenvironment is a fresh water sedimentary environment.These features are consistent with the geological setting of the basin.Comparative studies of isoheptane,heptane,and the carbon isotopic compositions of methane in natural gases,and other maturity indices indicated that natural gases in the Turpan-Hami Basin are dominated by low-mature gas formed during the low evolution stage of Jurassic coal seams.The parent materials are of type III,and the maturation degree was in the low evolution stage.These are the fundamental characteristics of low-mature gas.Results of light hydrocarbon research provided further evidence to suggest that the Turpan-Hami Basin is a large-scale gas producer of low-mature gas in China.It is likely that this resource will play an important role in future exploration and development of low-mature gas in China.

Zircon U-Pb SHRIMP Ages from the Late Paleozoic Turpan-Hami Basin,NW China

Permian volcanic rocks are widely distributed in the Turpan-Hami Basin, which is part of the Central Asian orogenic belt. Here we present SHRIMP zircon data for the rhyolite in Well Baocan 1, one of the deepest wells in the basin. The 283.9±2.7 Ma reported in our study provides the best precise age determination for the Yierxitu Formation, the oldest Permian layer of Hami Depression, one of the three substructural units of the Turpan-Hami Basin, and a potential hydrocarbon reservoir in this basin. Our data refines earlier imprecise 39^Ar-40^Ar ages and shows that the volcanic rocks both inside the Turpan-Hami Basin and along its margin are almost coeval. We delineate a collisional orogenesis, and the new age of 283.9±2.7 Ma may limit the latest time of the collision orogenesis.

吐哈盆地丘东洼陷碱泉子沟断裂描述及致密油气控藏分析

走滑断裂在油气成藏中具有重要的控制作用,其识别、判断和对油气藏控制要素的研究分析是当前勘探的热点。文中首次在吐哈盆地台北凹陷丘东洼陷中部发现碱泉子沟断裂,为了落实其空间展布特征、成因机制及其对油气藏的控制作用,开展了进一步研究。结果表明:碱泉子沟断裂在露头上水平错动、在剖面上断面陡直且发育“花状构造”、在平面上呈“雁列式”展布,并具有“四层构造”特征,走滑特征明显;碱泉子沟断裂是照壁山大断裂的派生次级走滑断裂,沿Sylveser简单剪切模式中的R′剪切面发育,结合流体包裹体均一温度推测其形成于晚印支期,早—中燕山期活动强烈,晚燕山期活动减弱;碱泉子沟断裂具有控圈、控储、控运和控藏作用,其空间结构、活动期次和与成藏期次的匹配关系决定油气运聚的流体相态、油气排替顺序和聚集位置,尤其是断裂中下层结构在中燕山期活动,后续静止封闭,这是导致下侏罗统致密油气藏大面积分布的重要原因。研究成果对吐哈盆地致密油气勘探具有非常重要的指导意义。

Paleogeothermal gradient and geologic thermal history of the Turpan-Hami Basin, Xinjiang

Synthetical research has been done on the geological thermal history of the Turpan-Hami Basin by using vitrinite reflectance, fluid inclusion geothermometry and fission track. The geotcmperature of the Turpan-Hami Basin has the character that suggests higher temperature in the past, in the east and south of the basin, and in the areas of large-fracture, and lower temperature in the present day and in the west and north of the basin. This feature is controlled by the difference of burial depth of basement and heat flow values, which made Permian source rock mature in the late Triassic and Jurassic source rock mature at the end of Jurassic and the early Tertiary.

吐哈盆地柯柯亚地区致密砂岩气储层“甜点”类型及成因

柯柯亚地区中-下侏罗统水西沟群致密砂岩气资源丰富,对其储层"甜点"类型和成因的研究可为吐哈盆地乃至其他地区致密砂岩气的勘探开发提供借鉴。通过物性统计、岩心观察、薄片分析、裂缝统计、测井解释和产量对比等研究,认为吐哈盆地柯柯亚地区水西沟群致密砂岩气发育孔隙型和裂缝型2种"甜点"类型。在沉积微相、矿物组成、地层水研究及盆地埋藏史、盆地演化史模拟的基础上,指出特定的沉积微相(水下分流河道和河口坝)、相对较弱的压实作用和相对较强的溶蚀作用是孔隙型"甜点"形成的主要原因,而强烈的构造抬升运动和储层所处的特殊构造位置是裂缝型"甜点"发育的主控因素。综合研究认为,吐哈盆地孔隙型和裂缝型"甜点"是沉积、成岩和构造运动等多种因素共同作用的结果。

吐哈盆地水溶气组分与同位素特征形成机理及意义探讨

测量了吐哈盆地 6个水溶气样品的组分和碳同位素值 ,并通过与盆地天然气的对比 ,探讨了水溶气组分及碳同位素特征形成机理及其应用的可能性。水溶气基本受制约于烃类气体溶解度的特征 ,与盆地天然气应属同源 ,但二者也存在明显的差异 ,如C1/C1～ 5值水溶气应大于天然气 ,实际反而较小 ,甲烷同系物碳同位素均较天然气富集13 C。作者认为这些特征的形成与水溶气的溶解量小于扩散运移量相关 。

沉积环境中古盐度的恢复——以吐哈盆地西南缘水西沟群泥岩为例

用锶钡法、硼元素法、钾钠比值和沉积磷酸盐法推算了吐哈盆地西南缘水西沟群沉积古水介质环境。认为,在水西沟群沉积时期,古水介质总体为淡水环境[m(Sr)/m(Ba)<1、m(B)为12.30×10-6～64.20×10-6],且自八道湾组—西山窑组沉积时期古水介质逐渐变淡:八道湾组沉积时期,古水介质盐度平均为2.28‰;三工河组沉积时期,平均为2.23‰;西山窑组沉积时期,平均为2.07‰.此外,对恢复沉积环境古盐度的其他方法进行了讨论,并指出了各种方法的局限性。

基于多层次模糊数学的中国低煤阶煤层气选区评价标准——以吐哈盆地为例

中国低煤阶含煤盆地煤层厚度大,储层物性好,煤层气资源丰富,而对于低煤阶煤层气有利区优选评价目前还没有成型的模型,本文以占全国低煤阶煤层气总资源量50%的吐哈盆地为例,运用多层次模糊数学的思路,对资源因素、煤储层因素、保存因素以及次一级影响因素共计19项参数,进行关键要素定量排序,针对吐哈盆地特有的成藏地质条件建立了煤层气选区评价标准,通过"赋值加权求和定量排序"的方法,探讨了中国低煤阶煤层气评价标准及主控因素对煤层气赋存的影响。研究表明:吐哈盆地二级构造单元沙尔湖浅凹陷、大南湖浅凹陷和哈密凹陷是适合煤层气勘探开发的有利目标区。

吐哈盆地中央构造带正反转演化特征

吐哈盆地中央构造带由火焰山构造和七克台构造组成。中央构造带形成于三叠纪晚期至侏罗纪早期,表现为伸展构造特征,生长断层上盘地层厚度明显大于下盘,并于断层上盘所在的台北凹陷形成沉降中心。晚侏罗世,由于拉萨陆块与欧亚大陆的碰撞作用导致吐哈盆地由伸展盆地转变为挤压盆地,中央构造带也于此时发生构造反转,由早期的伸展正断层转变为挤压逆断层。发生于55Ma的喜山构造事件对天山地区产生了深刻的影响,但影响时间略有滞后,大致发生在晚渐新世至早中新世,中央构造带即在此次构造事件中强烈变形,逆冲出露于地表。