试论渤海湾盆地油气富集规律与勘探

渤海湾盆地至今已发现油气田226个,探明油气地质储量114.4×108t,油气资源量为285×108t。盆地内的油气富集规律与盆地东界的郯庐深大断裂带紧密相关。靠近郯庐断裂带的东部坳陷区,其探明油气地质储量和油气资源量是远离断裂带的西部坳陷区的3.6倍和3.3倍;根据探明油气地质储量进行划分,东部坳陷区以大油气田为主,而西部坳陷区则以中、小油气田为主;东部坳陷区发现的浅层油气藏、稠油油藏、火成岩油藏及非烃CO2气藏比西部坳陷区多得多,但两者的潜山油气藏的数量和储量却很相近。研究表明,郯庐深大断裂不仅控制了盆地的发育和形成,而且还控制了油气的生成、运移和聚集。渤海湾盆地既是中国大盆地中油气富集程度最高的盆地,也是具有独特油气富集规律的盆地。尽管该盆地油气探明率已达40.1%,但仍有170.7×108t的油气剩余资源量可供再勘探,勘探潜力仍十分巨大。     

埕岛油田成烃特征与油气分异作用

埕岛油田的烃类在含油时代和空间位置上均具有分布多样性和复杂性的特点。来自不同油气源的烃类的初始分异作用造成了原油的成熟度、有机质性质和原始母质沉积环境的差异;油气在运聚过程中的分异作用使斜坡带前第三系存在逆向差异聚集现象;热动力作用造成原油密度和粘度从凹陷中心至凸起部位逐渐增大;油气聚集后的分异作用使研究区上第三系馆陶组上段原油普遍遭受到Ⅱ级轻度生物降解的破坏作用,造成馆陶组上段的原油以稠油为主。     

Groundwater potentiometric decline in the Springfield, Missouri area

The decline of the potentiometric surface of the Ozark aquifer underneath Springfield Missouri intensified during the 1980s and has been of concern since. From 1990 to the present, the shifting of population from urban to rural areas and water management changes to use more surface water created an opportunity for groundwater levels to recover. However, in 2002 private well owners reported low levels and water problems, which prompted mapping the new cone of depression. To this purpose, well data measured from private wells and data available elsewhere were mapped using GIS mapping tools. The results show a cone of depression extending towards the recently developed areas south of Springfield while the potentiometric levels of some areas within the city had recovered. The maps show that, compared to the 1987 conditions, the present cone of depression has changed significantly in extent and shape while its maximum depth has changed only slightly.     

Oxygen isotope and geochemical variations in the Missouri River

Oxygen isotope ratios in streamflow of the Missouri River basin vary geographically due to differences in source precipitation and the integration of waters from upstream regions. Average '¹⁸O values in the Missouri River main stem systematically increase from less than -17‰ in the headwaters to about -9‰ in the lower basin. Seasonal variations at a given location result from fluctuations in meteoric precipitation, residence time in reservoirs and groundwater systems, evaporation, and snowmelt. Average water chemistry values are successfully predicted for the upstream stations of two reaches on the lower Missouri River based on changes in discharge along each reach and water quality measurements collected at the downstream stations. Source regions for some dissolved ions found in the lower Missouri River are also identified. Sodium and sulfate originate predominantly from the basin above Sioux City, Iowa, while nitrate is largely derived from agricultural regions below Sioux City.     

Quaternary sediments and their weathering history in northcentral Missouri

Quaternary strata in northcentral Missouri were deposited prior to, during, and subsequent to glaciation of the area. Major depositional units are separated by buried soils. The lower Quaternary Whippoorwill formation is derived from local bedrock and has the intensely weathered New Florence soil developed in it. The pre-Illinoian McCredie formation, primarily till, is derived from distant shield and local cratonic rocks. The moderately weathered Kingdom City soil within the formation suggests that an intcrglacial separated two ice advances. The lllinoian Lovcland and Wisconsinan Peoria Loesses are derived from Missouri River outwash. Since glaciation, the welded Yarmouth-Sangamon Soil has developed in till and in lllinoian loess on stable sites but middle and late Sangamon Soils have developed on erosional surfaces. Holocene soils are developed in Wisconsinan loess and alluvium-colluvium.     

Hydrocarbon components in carbonaceous meteorites

Currently, the presence of free n-alkanes and isoprenoid alkanes in carbonaceous meteorites is usually explained either by microbial contamination during the period between the meteorite fall and collection or by contamination from the environment of analytical laboratories and museums. The goal of this research was to repeat analysis of hydrocarbon components in meteorites and to investigate possible meteorite contamination routes discussed in the literature. Experimental analysis of free organic constituents in five carbonaceous meteorites by infrared spectroscopy (IR) and gas chromatographic (GC) methods confirmed the presence of extractable aliphatic components, n-alkanes in the C₁₅H₃₂-C₂₇H₅₆ range and isoprenoid alkanes (phytane, pristane, and norpristane), in some of these meteorites. The contents of these compounds vary depending on the source. Insoluble organic components of two meteorites (meteorite kerogens) were isolated, and their composition was analyzed by IR and cracking/GC methods. Comparison with the data on several terrestrial contamination sources proposed in the literature shows that the presence of free saturated hydrocarbons in meteorites and the composition of the meteorite kerogen could not be explained either by microbial contamination or by contamination from the laboratory environment. The types of the hydrocarbons in meteorites resemble those typical of ancient terrestrial deposits of organic-rich sediments, except for the absence of lighter hydrocarbons, which apparently slowly evaporated in space, and multi-ring naphthenic compounds of the biologic origin, steranes, terpanes, etc. The prevailing current explanation for the presence of free linear saturated hydrocarbons in carbonaceous meteorites, apart from contamination, is the abiotic route from hydrogen and carbon monoxide. However, the data on the structure of meteorite kerogens require a search for different routes that initially produce complex polymeric structures containing n-alkyl and isoprenoid chains which are attached, via polar links (esters, salts, etc.), to a cross-linked polymer matrix. Later, the polymer slowly decomposes with the liberation of free aliphatic hydrocarbons.     

塔里木盆地奥陶系烃源岩二次生烃研究

为研究海相烃源岩二次生烃规律和塔里木盆地生排烃规律,以塔里木盆地奥陶系烃源岩为研究对象,首先通过构造-热演化史和生烃史研究得出,塔里木盆地典型构造单元奥陶系烃源岩具有二次生烃的特征,并且起始成熟度和生烃期次不同。然后选取自然条件下演化至不同起始成熟度的奥陶系海相烃源岩,采用热压模拟实验方法系统研究其二次生烃规律。研究表明：塔里木盆地奥陶系海相烃源岩二次生烃的主控因素是起始成熟度,二次生烃产率随起始成熟度增加规律性减小;低成熟和中成熟烃源岩具有大量生排油气潜力,出现相对延迟的生油高峰,高成熟烃源岩没有大量生油和生气的能力;两次不连续生烃量与一次连续生烃量的差值也受起始成熟度控制,具有阶段性;起始成熟度在低成熟到成熟阶段时,二次不连续生烃过程会增加烃源岩的生烃量,使生烃潜力增加,而高成熟阶段以后,二次不连续生烃过程就会减少烃源岩的生烃量,使生烃潜力减小。     

Clinal variation of some mammals during the Holocene in Missouri

Eastern cottontail (Sylvilagus floridanus), fox squirrel (Sciurus niger), and gray squirrel (Sciurus carolinensis) were examined for clinal variation during the Holocene. Modern samples of all three species displayed strong east-west patterns along the western edge of the eastern deciduous forest: S. floridanus and S. niger decrease and S. carolinensis increases in size. Archeological samples of S. carolinensis from Rodgers Shelter (23BE125), Benton County, Missouri, and Graham Cave (23MT2), Montgomery County, Missouri, indicated an increase in size from early to middle Holocene. Sylvilagus floridanus from Rodgers Shelter decreased in size from early to middle Holocene and then increased during the late Holocene to modern proportions. A literature survey reveals that clinal variation is a common phenomenon among modern homeotherms. In introduced species, clinal variation has developed after relatively few generations, indicating rapid adaptations to environmental conditions; often winter climatic variables are implicated. Morphological variation in the study species during the Holocene is interpreted as a response to changing climates. Studies of morphological clines may lead to another valuable data source for reconstructing past ecologies.     

Rapid transport of anthropogenic lead through soils in southeast Missouri

To investigate Pb transport and cycling, soils from the forest floor and cores from White Oaks (Quercus alba L.) were collected near a Pb smelter in SE Missouri at varying depths from the surface and varying distances. Lead concentrations in soil samples at the surface drop dramatically with distance from approximately 1500 mg/kg at less than 2 km from the smelter to around 100 mg/kg at localities greater than 2 km from the smelter. Lead contents in tree rings are below 0.5 mg/kg in samples dated prior to 1970, and rapidly increase in 1975–1990 samples. Isotopic compositions of soils and tree rings exhibit systematic variations of Pb isotopic compositions with depth and tree ring age. Distinguishable isotopic signatures for Pb sources allowed quantification of the contribution of smelter Pb to the soils. At depths where Pb concentrations decreased and approached constant values (10–25 cm, 10–30 mg/kg), 50–90%, 40–50% and 10–50% of the Pb could be derived from the smelter for the samples at locations less than 2, 2–4 and over 4 km from the smelter, respectively. The remaining portion was attributable to automobile emission and bedrock sources. Because the smelter operated from 1963 to 2003 and samples were collected in 1999, it is estimated that smelter Pb infiltrates at rates of 1 cm/yr (30 cm in 30 yr). At distances less than 1.5 km from the smelter, even though Pb concentrations become asymptotic at a depth of 30 cm, isotopic evidence suggests that Pb has migrated below this depth, presumably through exchange with naturally occurring Pb in the soil matrix. This implies that soils heavily polluted by Pb can exceed their Pb carrying capacity, which could have potential impacts on shallow groundwater systems and risk further exposure to human and ecological receptors.     

贵州水城煤中基质镜质体生烃潜力、烃类组成及生烃模式

基质镜质体是华南晚二叠世煤中的主要组分之一,其在煤中含量的多少、生烃潜力的大小、生烃特性等直接影响到该区煤成油气资源的评价。采用岩石热解、热解气相色谱以及开放体系下热模拟等方法,对贵州水城晚二叠世(R12)龙潭组煤中基质镜质体的生烃潜力、烃类组成特征、生烃模式进行了研究。结果表明：本区基质镜质体的生烃潜力、氢指数分别为191.99mg/g和250mg／gTOC,远高于丝质体的生烃潜力(26.17mg/g)和氢指数(35mg／gTOC),而小于树皮体的生烃潜力(297mg/g)和氢指数(491mg/gTOC);基质镜质体热解烃类组成中以轻质烃为主,湿气次之,可见本区基质镜质体不但能生成气态烃,而且能生成一定量的液态烃,这归因于其中所含大量的超微类脂体;基质镜质体“生油窗”温度范围为375～475℃,主要生烃温度区间为400～450℃,其中415～430℃为生烃高峰期,420℃处产烃率最高。基质镜质体这种在高成熟度下(大于VRo1.0％)大量生烃的特点对在成熟度普遍较高的华南地区寻找油气田具有重要的意义。     

Earthquake-Induced Deformation Analysis of a Bridge Approach Embankment in Missouri

Earthquake-induced deformations for a bridge approach earth embankment are predicted using a calibrated numerical model. The constitutive soil model is a modified hyperbolic model that uses Masing rules and incremental pore pressure relations. The model was calibrated using both laboratory and field data. A shaking table physical model was used to verify the numerical simulation. Additionally, the upper San Fernando dam was modeled to reproduce the deformations in the 1971 earthquake. The subsurface and embankment soil conditions were characterized using field and laboratory methods. The model developed was used to predict the earthquake-induced deformations of an approach embankment to Bridge A1466 in the NMSZ near Hayti, Missouri, where strong earthquakes M > 7.0 are anticipated in the next 50 years.     

Composition of arsenopyrite from topaz greisen veins in southeastern Missouri

Arsenopyrite occurs in greisen-sulfide veins hosted by unmetamorphosed Precambrian granite and rhyolite in the Silver Mine district of southeastern Missouri, Greisenization and sulfide mineralization appear to have been a continuous depositional sequence which recorded falling temperature in a near-surface vein environment. Textural criteria imply that equilibrium existed between arsenopyrite and pyrite and that this pair crystallized in an intermediate paragenetic position between the greisen and hydrothermal stages. Thirty-eight electron microprobe spot analyses of 15 arsenopyrite crystals from the Einstein and Gabriel veins failed to disclose chemical zoning of As/S. The compositional range of the analyzed arsenopyrites is 32. 9 to 31. 0 atomic % As. A range of arsenopyrite crystallization temperature from 485°C (±15°) to 455°C (±15°) is indicated for the Gabriel vein. In contrast, arsenopyrites from the Einstein vein record a lower and broader crystallization range of 440°C (±15°) to 368°C (±15°).     

二次生烃的蓝移特征

<正> 二次生烃是指烃源岩在受热温度降低导致一次生烃历程被中止后,受热温度再次增高并达到有机质再次活化所需的临界热动力学条件,烃源岩再次发生生烃演化。广义上,烃源岩在地质历史时期可能经历过多次的生烃中止与活化,发生三次甚至更多次数的生烃作用。李田忠等将一次生烃之后的历次生烃作用统称为二次生烃。伴随荧光分析技术的逐步完善,人们发现了蓝移现象,在进行二次生烃热模拟实验时,发现随着热模拟温度的升高,荧光颜色出现蓝移。当烃源岩原始成熟度超过生油窗上界时,显微组分荧光应该消失,但在试验中却发现显微组分仍具荧光。实际的蓝移现象是两种:一种指的是随着激发时间的增     

Hydrocarbon migration in the Solway Basin

Carboniferous rocks in the north Solway onshore outcrop show evidence of hydrocarbon migration. Oil residues occur as intergranular bitumen in sandstones, thoriferous bitumen nodules in sandstones and uraniferous bitumens in fractures associated with the North Solway Fault at the northern margin of the Solway Basin. Oil was emplaced in sandstones after the dissolution of dolomite, calcite and clay cements. The radioelement-rich bitumens represent deposition following interactions between migrating hydrocarbons and metalliferous fluids. The close proximity of the Caledonian Criffel granodiorite, unroofed by Carboniferous times, suggests that the pluton was the source of uranium and thorium. Hydrocarbon source rocks are identified further east in the more complete succession exposed in the Esk Valley region, along with further oil residues. Time-temperature modelling suggests that oil was generated from Lower Carboniferous source rocks during the Permo-Triassic. Chemical age dating of uraninite in bitumen yields early Jurassic ages, which may reflect the time of hydrocarbon migration along the North Solway Fault system, and may be related to a mid-Jurassic episode of regional uplift. Analyses of thorite in bitumen nodules give a wider spread of data, probably due to the migration of daughter lead.     

贵州水城煤中基质镜质体生烃潜力、烃类组成及生烃模式

基质镜质体是华南晚二叠世煤中的主要组分之一,其在煤中含量的多少、生烃潜力的大小、生烃特性等直接影响到该区煤成油气资源的评价。采用岩石热解、热解气相色谱以及开放体系下热模拟等方法,对贵州水城晚二叠世(P21)龙潭组煤中基质镜质体的生烃潜力、烃类组成特征、生烃模式进行了研究。结果表明:本区基质镜质体的生烃潜力、氢指数分别为191.99mg/g和250mg/gTOC,远高于丝质体的生烃潜力(26.17mg/g)和氢指数(35mg/gTOC),而小于树皮体的生烃潜力(297mg/g)和氢指数(491mg/gTOC);基质镜质体热解烃类组成中以轻质烃为主,湿气次之,可见本区基质镜质体不但能生成气态烃,而且能生成一定量的液态烃,这归因于其中所含大量的超微类脂体;基质镜质体“生油窗”温度范围为375～475℃,主要生烃温度区间为400～450℃,其中415～430℃为生烃高峰期,420℃处产烃率最高。基质镜质体这种在高成熟度下(大于VRo1.0%)大量生烃的特点对在成熟度普遍较高的华南地区寻找油气田具有重要的意义。     

中国南方海相烃源岩中笔石生烃能力研究

我国南方海相页岩中普遍发育的笔石与海相页岩气成因具有密切的关系,但笔石是否具有页岩气生烃能力,一直未有可靠的、直接的相关实验证实。本文通过采集笔石含量丰富的黑色页岩,手工挑选纯笔石样品并进行热解生烃模拟实验研究,证实了笔石页岩中的笔石是一种较好的生烃母质。笔石样品的碳含量较高,贡献了笔石页岩的大部分碳来源。达到生油高峰后的笔石热解生烃产物主要为天然气-轻质油,这两部分生烃产物占总生烃产物的94%以上,且其中的气态烃占总烃比例达到了54%左右。分析认为,笔石的热解生烃特征介于Ⅲ型有机质和Ⅱ型有机质之间,近似于Ⅲ型有机质生烃特征,以气态烃产物为主。由此推论,在笔石热成熟演化过程中,其有机质生烃能力可能更高,与目前南方广泛发育页岩气的成因息息相关。     

河流深槽沉积体与油气的关系——以辽河坳陷大25井区为例

河流深槽沉积体是河流沉积的一种特殊沉积体。辽河坳陷第三纪断裂活动强烈，火山岩广泛分布，形成了独特的地貌条件，具备形成河流深槽沉积体的地质条件。本文以辽河坳陷东部凹陷大２５井区为例，对河流深槽沉积体的成因及特征进行探讨，证实了大２５井区巨厚砂砾岩沉积是河流在火山岩古地形的限制下发生急转弯，在其变曲河段的深槽中沉积的深槽沉积体。该沉积体中发育良好的储集空间，有利于油气储集。该类储集体的发现，丰富了辽河坳陷的储层类型，为油气勘探提供了新的领域。     

黔南坳陷海相优质烃源岩的生烃潜力及时空分布

黔南坳陷典型古油气藏的精细解剖对南方海相油气勘探有借鉴意义.本文利用沉积、有机岩石学和地球化学等综合手段,建立了黔南坳陷麻江古油藏、凯里残余油气藏地区和雪峰隆起西缘的二叠系-震旦系地球化学综合剖面,重点探讨了该地区优质烃源岩的生烃潜力和时空分布.黔东南地区,纵向自震旦系至二叠系均有烃源岩发育,其中早寒武世初期和二叠纪发育有两套优质烃源岩,以下寒武统盆地相、斜坡相的黑色页岩发育最好,有机质丰度高(TOC普遍大于2%),类型好(偏腐殖型),厚度大,是气候变暖、海平面上升和生物大爆发等全球性重大地质事件的耦合作用下,由热液活动、上升洋流等共同引起的高古生产力和缺氧环境控制的产物,是本地区大中型油气田形成的主要物质基础.二叠纪盆地相和泻湖相中发育的优质烃源岩对黔中隆起及其周缘地区油气成藏也具有重要作用.     

Dynamic Field Division of Hydrocarbon Migration,Accumulation and Hydrocarbon Enrichment Rules in Sedimentary Basins

Hydrocarbon distribution rules in the deep and shallow parts of sedimentary basins are considerably different, particularly in the following four aspects. First, the critical porosity for hydrocarbon migration is much lower in the deep parts of basins: at a depth of 7000 m, hydrocarbons can accumulate only in rocks with porosity less than 5%. However, in the shallow parts of basins (i.e., depths of around 1000 m), hydrocarbon can accumulate in rocks only when porosity is over 20%. Second, hydrocarbon reservoirs tend to exhibit negative pressures after hydrocarbon accumulation at depth, with a pressure coefficient less than 0.7. However, hydrocarbon reservoirs at shallow depths tend to exhibit high pressure after hydrocarbon accumulation. Third, deep reservoirs tend to exhibit characteristics of oil (–gas)–water inversion, indicating that the oil (gas) accumulated under the water. However, the oil (gas) tends to accumulate over water in shallow reservoirs. Fourth, continuous unconventional tight hydrocarbon reservoirs are distributed widely in deep reservoirs, where the buoyancy force is not the primary dynamic force and the caprock is not involved during the process of hydrocarbon accumulation. Conversely, the majority of hydrocarbons in shallow regions accumulate in traps with complex structures. The results of this study indicate that two dynamic boundary conditions are primarily responsible for the above phenomena: a lower limit to the buoyancy force and the lower limit of hydrocarbon accumulation overall, corresponding to about 10%–12% porosity and irreducible water saturation of 100%, respectively.