Exploration breakthrough and factors for enrichment and high-yield of hydrocarbons in ultra-deep clastic rocks in Linhe Depression,Hetao Basin,NW China

Based on drilling and logging data,as well as geological experiments,the geological characteristics and factors controlling high-yield and enrichment of hydrocarbons in ultra-deep clastic rocks in the Linhe Depression,Hetao Basin,are studied.The results are obtained in four aspects.First,the inland saline lacustrine high-quality source rocks developed in the Paleogene in the Linhe Depression have the characteristics of early maturity,early expulsion,high hydrocarbon yield,and continuous and efficient hydrocarbon generation,providing an important resource basis for the formation of ultra-high pressure and high-yield reservoirs.Second,the weak compaction,early charging,and weak cementation for pore-preserving,together with the ultra-high pressure for pore-preserving and fracture expansion to improve the permeability,leads to the development of high-quality reservoirs with medium porosity(greater than 15%)and medium permeability(up to 226×10^(-3)μm^(2))in the ultra-deep strata(deeper than 6500 m),which represents a greatly expanded space for oil and gas exploration.Third,the Linhe Formation adjacent to the trough exhibits a low net-to-gross(NTG)and good reservoir-caprock assemblage,and it is overlaid by very thick high-quality mudstone caprock,which are conducive to the continuous and efficient hydrocarbon generation and pressurization and the formation of ultra-high pressure oil and gas reservoirs.Fourth,the most favorable targets for ultra-deep exploration are the zones adjacent to the hydrocarbon generating center of the Paleogene Linhe Formation and with good tectonic setting and structural traps,mainly including the Xinglong faulted structural zone and the Nalinhu faulted buried-hill zone.The significant breakthrough of ultra-deep oil and gas exploration in the Linhe Depression reveals the good potential of ultra-deep clastic rocks in this area,and provides valuable reference for oil and gas exploration of ultra-deep clastic rocks in other areas.

Enrichment model and major controlling factors of below-source tight oil in Lower Cretaceous Fuyu reservoirs in northern Songliao Basin,NE China

Based on the geochemical,seismic,logging and drilling data,the Fuyu reservoirs of the Lower Cretaceous Quantou Formation in northern Songliao Basin are systematically studied in terms of the geological characteristics,the tight oil enrichment model and its major controlling factors.First,the Quantou Formation is overlaid by high-quality source rocks of the Upper Cretaceous Qingshankou Formation,with the development of nose structure around sag and the broad and continuous distribution of sand bodies.The reservoirs are tight on the whole.Second,the configuration of multiple elements,such as high-quality source rocks,reservoir rocks,fault,overpressure and structure,controls the tight oil enrichment in the Fuyu reservoirs.The source-reservoir combination controls the tight oil distribution pattern.The pressure difference between source and reservoir drives the charging of tight oil.The fault-sandbody transport system determines the migration and accumulation of oil and gas.The positive structure is the favorable place for tight oil enrichment,and the fault-horst zone is the key part of syncline area for tight oil exploration.Third,based on the source-reservoir relationship,transport mode,accumulation dynamics and other elements,three tight oil enrichment models are recognized in the Fuyu reservoirs:(1)vertical or lateral migration of hydrocarbon from source rocks to adjacent reservoir rocks,that is,driven by overpressure,hydrocarbon generated is migrated vertically or laterally to and accumulates in the adjacent reservoir rocks;(2)transport of hydrocarbon through faults between separated source and reservoirs,that is,driven by overpressure,hydrocarbon migrates downward through faults to the sandbodies that are separated from the source rocks;and(3)migration of hydrocarbon through faults and sandbodies between separated source and reservoirs,that is,driven by overpressure,hydrocarbon migrates downwards through faults to the reservoir rocks that are separated from the source rocks,and then migrates laterally through sandbodies.Fourth,the differences in oil source conditions,charging drive,fault distribution,sandbody and reservoir physical properties cause the differential enrichment of tight oil in the Fuyu reservoirs.Comprehensive analysis suggests that the Fuyu reservoir in the Qijia-Gulong Sag has good conditions for tight oil enrichment and has been less explored,and it is an important new zone for tight oil exploration in the future.

Differential Hydrocarbon Enrichment and its Main Controlling Factors in Depressions of the Bohai Bay Basin Differential Hydrocarbon Enrichment and its Main Controlling Factors in Depressions of the Bohai Bay Basin

Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin.There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon generation, migration and accumulation, contains significantly different hydrocarbon generation conditions and enrichment degree. On the basis of previous documents and a large number of statistical data, this work comparatively analyzed the differential hydrocarbon enrichment and its major controlling factors in depressions of the Bohai Bay Basin. The results show that depressions in the Bohai Bay Basin have various hydrocarbon enrichment degrees, and can be categorized into four types, namely enormously oil-rich, oil-rich, oily and oil-poor depressions. In general, the enormously oil-rich and oil-rich depressions are distributed in the eastern part of the basin along the Tan-Lu and Lan-Liao faults, whereas depressions in the western part of the basin are poor in hydrocarbons. Moreover, the vertical distribution of hydrocarbons is also highly heterogeneous, with Pre-Paleogene strata rich in hydrocarbons in the northern and western depressions, Paleogene strata rich in hydrocarbons in the entire basin, and Neogene strata rich in hydrocarbons in the off-shore areas of the Bohai Bay Basin. From early depressions in onshore areas to the late depressions in offshore areas of the Bohai Bay Basin, the source rocks and source-reservoir-cap rock assemblages gradually become younger and shallower, and the hydrocarbon resource abundance gradually increases. Hydrocarbon supplying condition is the key factor constraining the hydrocarbon enrichment for different depressions,while the main source-reservoir-cap rock assemblage, sufficient hydrocarbons and the transportation capacity of faults control the vertical distribution of hydrocarbons. The main factors controlling hydrocarbon enrichment are different for different layers. The hydrocarbon supplying condition of source rocks is the key controlling factor, whereas the source-reservoir configuration, the main sourcereservoir-cap rock assemblages, and the fault transportation are the main factors of hydrocarbon enrichment in the Paleogene, Paleogene and Neogene, respectively.

Enrichment factors of movable hydrocarbons in lacustrine shale oil and exploration potential of shale oil in Gulong Sag,Songliao Basin,NE China

The geological characteristics and production practices of the major middle-and high-maturity shale oil exploration areas in China are analyzed.Combined with laboratory results,it is clear that three essential conditions,i.e.economic initial production,commercial cumulative oil production of single well,and large-scale recoverable reserves confirmed by the testing production,determine whether the continental shale oil can be put into large-scale commercial development.The quantity and quality of movable hydrocarbons are confirmed to be crucial to economic development of shale oil,and focuses in evaluation of shale oil enrichment area/interval.The evaluation indexes of movable hydrocarbon enrichment include:(1)the material basis for forming retained hydrocarbon,including TOC>2%(preferentially 3%-4%),and typeⅠ-Ⅱkerogens;(2)the mobility of retained hydrocarbon,which is closely related to the hydrocarbon composition and flow behaviors of light/heavy components,and can be evaluated from the perspectives of thermal maturity(Ro),gas-oil ratio(GOR),crude oil density,quality of hydrocarbon components,preservation conditions;and(3)the reservoir characteristics associated with the engineering reconstruction,including the main pore throat distribution zone,reservoir physical properties(including fractures),lamellation feature and diagenetic stage,etc.Accordingly,13 evaluation indexes in three categories and their reference values are established.The evaluation indicates that the light shale oil zones in the Gulong Sag of Songliao Basin have the most favorable enrichment conditions of movable hydrocarbons,followed by light oil and black oil zones,containing 20.8×10^(8) t light oil resources in reservoirs with R_(0)>1.2%,pressure coefficient greater than 1.4,effective porosity greater than 6%,crude oil density less than 0.82 g/cm^(3),and GOR>100 m/m^(3).The shale oil in the Gulong Sag can be explored and developed separately by the categories(resource sweet spot,engineering sweet spot,and tight oil sweet spot)depending on shale oil flowability.The Gulong Sag is the most promising area to achieve large-scale breakthrough and production of continental shale oil in China.

Controlling factors and models of shale oil enrichment in Lower Permian Fengcheng Formation,Mahu Sag,Junggar Basin,NW China

Based on the combination of core observation,experimental analysis and testingand geological analysis,the main controlling factors of shale oil enrichment in the Lower Permian Fengcheng Formation in the Mahu Sag of the Junggar Basin are clarified,and a shale oil enrichment model is established.The results show that the enrichment of shale oil in the Fengcheng Formation in the Mahu Sag is controlled by the organic abundance,organic type,reservoir capacity and the amount of migration hydrocarbon in shale.The abundance of organic matter provides the material basis for shale oil enrichment,and the shales containing typesⅠandⅡorganic matters have good oil content.The reservoir capacity controls shale oil enrichment.Macropores are the main space for shale oil enrichment in the Fengcheng Formation,and pore size and fracture scale directly control the degree of shale oil enrichment.The migration of hydrocarbons in shale affects shale oil enrichment.The shale that has expelled hydrocarbons has poor oil content,while the shale that has received hydrocarbons migrated from other strata has good oil content.Lithofacies reflect the hydrocarbon generation and storage capacity comprehensively.The laminated felsic shale,laminated lime-dolomitic shale and thick-layered felsic shale have good oil content,and they are favorable lithofacies for shale oil enrichment.Under the control of these factors,relative migration of hydrocarbons occurred within the Fengcheng shale,which leads to the the difference in the enrichment process of shale oil.Accordingly,the enrichment mode of shale oil in Fengcheng Formation is established as"in-situ enrichment"and"migration enrichment".By superimposing favorable lithofacies and main controlling factors of enrichment,the sweet spot of shale oil in the Fengcheng Formation can be selected which has great significance for the exploration and development of shale oil.

Enrichment of tight oil and its controlling factors in central and western China

Taking the tight oil of the Zhongnan sag in the Ordos Basin,Jimusar sag in the Junggar Basin and Qingxi sag in the Jiuquan Basin as study objects,based on field survey,dissection of tight oil reservoirs,sample test,modeling experiment and comprehensive analysis,this study reveals that the tight oil accumulates at start-up pressure,advances under differential pressure,diffuses at alternating fast and low speeds,charges in stepped large area and migrates rapidly through fractures,and enriches in dominant fractures and pores.The root cause of ladder-like charge is the multiple scales of pores.The widespread source rock with high hydrocarbon generation intensity is the material basis for tight oil enrichment;the dominant source reservoir assemblage is the basic unit for tight oil enrichment;fractures and beddings are conducive to local rapid migration of tight oil;fractures and pores work together to control the enrichment of tight oil.Two typical accumulation models of tight oil are established,namely"source reservoir in coexistence,four optimal factors controlling enrichment around central area,and large-scale continuous distribution"for a large freshwater lake clastic rock basin and"source reservoir integration,four optimal factors controlling enrichment,central area distribution,small in size but high in enrichment degree"for a small saline lake diamictite depression.

An Assessment of Heavy-Metal Contamination in Soils within Auto-Mechanic Workshops Using Enrichment and Contamination Factors with Geoaccumulation Indexes

Soil characterization and heavy metals in different layers (0 - 15 cm;15 - 30 cm and 30 - 45 cm depth) of automobile mechanic waste dumps were studied. The soils showed remarkably high levels of all the metals above background concentrations with most (Ni, Cu, Fe, Cr and Cd) decreasing with soil depth. The distribution pattern were in the following order Fe > Cu > Zn > Pb > Cr > Ni > Cd. Across all the sampling locations and profiles, Fe and Cd showed the highest (476.4 μg·g-1) and least (37.5 μg·g-1) mean concentrations respectively. Pollution load index (PLI) and index of geoaccumulation (Igeo) revealed overall high and moderate contamination respectively but the enrichment factors (EFs) for Pb Ni and Cd are severe. The inter-element relationship revealed the identical source of elements in the soils of the studied area. The accuracy of the results has been cheeked using the standard reference material;SRM (PACS-2). The mechanic waste dumps represent potential sources of heavy metal pollution to environment. The elevated levels of heavy metals in these soil profiles constitute a serious threat to both surface and groundwater.

Controlling factors of marine shale gas differential enrichment in southern China

Based on the exploration and development practice of marine shale gas in Fuling, Weiyuan, Changning, Luzhou and Southeast Chongqing in southern China, combined with experiments and analysis, six factors controlling differential enrichment of marine shale gas are summarized as follows:(1) The more appropriate thermal evolution and the higher the abundance of organic matter, the higher the adsorption and total gas content of shale will be.(2) Kerogen pyrolysis and liquid hydrocarbon cracking provide most of the marine shale gas.(3) The specific surface area and pore volume of organic matter rich shale increased first and then decreased with the increase of thermal evolution degree of organic shale. At Ro between 2.23% and 3.33%, the shale reservoirs are mainly oil-wet, which is conducive to the enrichment of shale gas.(4) The thicker the roof and floor, the higher the shale gas content. The longer the last tectonic uplift time and the greater the uplift amplitude, the greater the loss of shale gas will be.(5) The buried depth and dip angle of the stratum have different controlling and coupling effects on shale gas in different tectonic positions, resulting in two differential enrichment models of shale gas.(6) The effective and comprehensive matching of source, reservoir and preservation conditions determines the quality of shale gas accumulation. Good match of effective gas generating amount and time, moderate pore evolution and good preservation conditions in space and time is essential for the enrichment of shale gas.

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

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.

Evaluation of Nutrients and Trace Metals and Their Enrichment Factors in Soil and Sugarcane Crop Irrigated with Wastewater

The study was conducted to investigate enrichment factor of wastewater (WW) irrigation to agricultural soils and the bioconcentration factor of trace metals uptake by sugarcane and to determine the concentrations of nutrients in sugarcane by growing the same on a contaminated soil, during the growth period of crop in Vidyaranyapuram area in the South West of Mysore, Karnataka. The concentrations of macronutrients and trace metals in the soil sampled sugarcane crop were found highly significant in Ca, Mg, K, Na, N, Mn, Cu, Ni and Cr. The enrichment factor was maximum for N and Na, and the values of N and Na were in the significant enrichment category. Whereas the values of following elements (K, P, Ca, SO4, Cu, Cr, Mg, Mn, Ni, Cd, Fe, Pb, Cl, Co and Zn) in soil irrigated with WW were in moderate enrichment category. The mean concentrations of N, P, K, Ca, Na, Fe, Mn, and Pb in sugarcane leaves in wastewater treatment crops were significantly higher than those with ground water (GW) treated which showed the lowest concentrations. Calculation of the bioconcentration factor (BCF) indicated that the accumulation of heavy metals in sugarcane crop was in the order Cd > Zn > Co > Pb > Mn > Ni > Cu > Cr > Fe. Pearson’s correlation coefficient indicated the relationship between different elements content in soil and plant. The results showed that the elements, Ca, Mg, Na, K, N, P, Mn, Zn and Cr, were significantly positively correlated, between the soil and the plant.

Factors Controlling Organic Matter Enrichment in Alkaline Lacustrine Source Rocks:A Case Study of the Late Paleozoic Fengcheng Formation in the Junggar Basin,NW China

The late Paleozoic Fengcheng Formation shale(LPF shale)in the Junggar Basin,NW China,is the oldest alkaline source rock discovered in the world,providing a unique perspective with which to explore organic matter(OM)enrichment in alkaline lake environments.Combined with the organic carbon isotope profile and paleoenvironmental proxies,this study reveals that the LPF shale was deposited in an arid climate with high salinity and a strong reducing environment,accompanied by frequent volcanic activity.High TOC values are concentrated in two intervals with frequent fluctuations in OM types.A negative excursion due to changes in sedimentary OM source is found in the δ^(13)C_(org) profile.The excursion corresponds to the OM enrichment interval and is accompanied by abnormally high values of Sr/Ba and Sr/Cu.This implies that the extreme arid climate has led to high salinity,resulting in strong reducibility and changes in paleontological assemblages,which in turn controlled the differential enrichment of OM.The Fengcheng Fm.high-quality source rocks are the result of the combined action of climatic events,volcanism,high-salinity water environment and superior hydrocarbon-generating organisms.The results provide new insights into the formation conditions of terrestrial alkaline high-quality source rocks and the factors controlling alkaline OM enrichment.

The enrichment characteristics and geological controlling factors of coalbed methane occurrence in Laochang area, Yunnan Province

The enriched characters of methane content in the main coal seam of Yunnan＇s Laochang coal mine was analyzed through combined with the geologic conditions of the research area： structure type, hydrogeology condition, coal reservoir＇s macerals, ash, water content, and so on. The geology factors of controlling gas in Laochang coal mine were illustrated; and the different geology models of controlling gas of geologic condition coupling were posed. Research shows that, in the region, the methane contents of the main coal seams decrease gradually from middle to all around it; the northeast and southeast is higher than the west. In the local area, the methane content of anticline axis is higher, and the gas content is reduced to both wings and plunging crown. On macroscopic view, the distribution of methane content in coal-beds was controlled by structural type. On microscopic view, the methane content in coal-beds is mainly involved in coal reservoir＇s macerals, ash content, and water content. The enriched characters of CBM in the research area are mainly the result of structure-hydrogeology-petrophysics coupling controls of CBM. On the basis of above analysis, according to the distribution character of methane content in coalbeds, the research area was divided into low gas area, middle gas area, and high gas area.

Assessment of Axial Power Peaking Factors in GHARR-1 LEU Core: A Decadal Simulation Analysis

This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.

准噶尔盆地东部隆起煤层气成藏条件与选区评价

准噶尔盆地东部隆起具有较好的煤层气勘探前景,开展煤层气选区与评价,将为该区煤层气勘探提供科学依据和勘探方向。利用探井钻测录试资料、岩心分析测试数据和地震资料,开展井—震标定和地震剖面解释,编制了侏罗系八道湾组和西山窑组煤层连井剖面和煤层厚度分布图;分析了研究区内煤层气气源、煤岩基本特征、储层物性、含气性和保存条件等成藏主控因素。研究表明:(1)西山窑组煤层在沙奇凸起以北五彩湾凹陷—梧桐窝子凹陷连片分布,在沙奇凸起以南则主要分布于吉木萨尔凹陷—吉南凹陷;八道湾组煤层分割性较强,主要分布于凹陷内部分地区。(2)区内存在自源型煤层生物成因气、低成熟热成因气和深部外源型高成熟气条件。(3)煤岩有机组分以惰质组为主,镜质组次之,壳质组少量;煤岩镜质组反射率低(0.39%~0.47%),为低煤级煤;煤岩瓦斯气体成分主要为N_(2)、CO_(2)和CH_(4),其中N_(2)占绝对优势;煤岩总含气量中可燃气体(CH_(4))含量低。(4)煤层气富集成藏模式分为山前断陷富集成藏模式、深部凹陷富集成藏模式和开放斜坡逸散模式。(5)建立了煤层气评价参数和划分标准,五彩湾凹陷、梧桐窝子凹陷、吉木萨尔凹陷和吉南凹陷为煤层气勘探有利区;沙帐断褶带和石钱滩凹陷为较有利区;石树沟凹陷和古城凹陷为不利区。

四川盆地东南部南川地区煤层气地质特征及富集主控因素

四川盆地东南部南川地区上二叠统龙潭组深层煤层气勘探取得重要战略突破,展现出该区煤层气良好的勘探潜力。为揭示其富集主控地质因素,利用钻井、岩心、测井及实验分析等资料,从龙潭组煤层分布、煤岩煤质、物性、含气性以及可压裂性特征等方面入手,开展了煤层气地质特征与富集主控地质因素研究。研究表明:(1)龙潭组主力煤层具有分布稳定(厚度2.8~5.7 m)、煤体结构好(主要为原生结构煤)、镜质组含量高(平均含量79.7%)、热演化程度较高(R_(o)平均为1.9%)和灰分产率较低(平均14.3%)的特点,具备形成煤层气藏的基本条件;(2)煤储层为孔隙—裂隙型储层,微孔占比78%,其比表面积占比达99.6%,有利于煤层气的吸附及压裂后渗流;(3)煤层总含气量为14.0~46.7 m^(3)/t,游离气占比为39%~44%,具有“高含气、富含游离气、过饱和”及含气量随埋深增加而增大的特征;(4)研究区地应力适中(35~60 MPa),两向水平应力差异系数小(<0.1),顶底板条件好,可形成良好的应力隔挡,有利于压裂改造;(5)南川地区煤层气富集主控地质因素为沉积环境控制含煤建造、演化程度控制生烃强度、保存条件控制富集程度。

用VEF值评价地铁车站内挥发性有机物的污染水平

[目的 ]评价地铁车站内站台和站厅挥发性有机物 (VOCs)的污染水平 ,并判断来源。 [方法 ]用气相色谱质谱联用仪对地铁车站站台和站厅挥发性有机物浓度进行测定 ,并用挥发性有机物富集指数 (VEF)进行分析。 [结果 ]两车站站台和站厅监测点白天及夜晚的CO2 浓度差异存在显著性 (P <0 .0 1) ,监测点白天和夜晚的VOCs浓度差异无显著性 (P >0 .0 5 )。地铁车站内VOCs的主要来源来自其自身室内排放源 ,室外污染物浓度及通风状况等可能对室内VOCs有影响。 [结论 ]地铁车站内存在VOCs污染 ,用VEF评价地铁车站内VOCs污染状况 ,能较简便、准确地反映其污染物来源 。

深部煤岩地质特征及煤层气富集主控地质因素——以鄂尔多斯盆地东部M区为例

鄂尔多斯盆地M区上石炭统本溪组顶部8#厚煤层分布广泛,有机质热成熟度高。该区煤层埋深大、横向变化快、非均质性强,且煤岩基础地质特征及深部煤层气富集规律尚不明确、有利目标优选标准尚未建立,这严重制约了深部煤层气的高效勘探。为了促进深部煤层气的增储和高效产出,进一步发展鄂尔多斯盆地东部深部煤层气富集理论,基于研究区76口井的岩心观察、实验分析测试、扫描电镜、测—录井资料,结合三维地震资料,开展了深部煤层地质特征及煤层气富集主控因素两方面的研究工作,初步明确了该区深部煤层气的勘探潜力。鄂尔多斯盆地M区上石炭统本溪组顶部8#煤以焦煤—瘦煤为主,为中高阶煤;亮煤和半亮煤厚度为2~6 m;有机组分以镜质组为主,占比79.8%;工业组分表现为中高挥发分及灰分、固定碳丰富、低水分;煤岩储层孔缝发育,以原生孔隙为主,其孔隙主要由微孔和大孔组成;含气量介于16~25 m^(3)/t之间。鄂尔多斯盆地东缘深部煤层气富集情况主要受煤储层、构造2个因素控制。以6 m以上的厚煤层发育区、远离断裂带(断距小于5 m)的裂缝发育区、微构造高点作为深部煤层气有利勘探区优选原则,优选出8#煤有利勘探面积共207 km^(2),其中Ⅰ类区97 km^(2),Ⅱ类区110 km^(2)。

2017—2022年扬州市大气PM_(2.5)中金属和类金属元素污染特征及健康风险评估

为探究扬州市大气细颗粒物(PM_(2.5))中金属和类金属元素的污染水平、来源及健康风险,于2017—2022年对扬州市大气PM_(2.5)进行定点连续采样。采用超声萃取电感耦合等离子体质谱法测定目标元素的浓度;运用中位数(四分位数间距)[M(P _(25),P_(75))]描述各元素的浓度分布特征;依据国家标准的浓度限值对污染水平进行系统评价。采用斯皮尔曼(Spearman)相关系数、富集因子和主成分分析对各元素来源进行深入探讨,结果显示,铊(Tl)、锑(Sb)、铅(Pb)、硒(Se)、镉(Cd)和砷(As)可能与化石燃料燃烧密切相关,镍(Ni)、铬(Cr)及锰(Mn)主要来源于工业排放,而铝(Al)元素则主要受扬尘影响。健康风险评估表明,在正常暴露情景下,As和六价铬(Cr^(6+))对2岁及以上人群存在潜在致癌风险;同时,As、Cr^(6+)和Cd的终生暴露亦具有一定的致癌风险,提示这些元素须作为重点监控对象。

Geological Factors Controlling the Accumulation and High Yield of Marine-Facies Shale Gas: Case Study of the Wufeng-Longmaxi Formation in the Dingshan Area of Southeast Sichuan, China

The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research.In this study,the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated.Shale cores underwent laboratory testing,which included the evaluation of total organic carbon(TOC),vitrinite reflectance(Ro),whole-rock X-ray diffraction(XRD),pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM).Based on the results of natural gamma ray spectrum logging,conventional logging,imaging logging,and seismic coherence properties,the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively.The results showed that(1)layer No.4(WF2-LM4)of the Wufeng-Longmaxi Formation has a Th/U ratio<2 and a Th/K ratio of 3.5–12.Graptolites and pyrite are relatively abundant in the shale core,indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2)The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen.There is a good correlation among TOC,Ro,gas content,and brittle minerals;the fracturing property(brittleness)is 57.3%.Organic and inorganic pores are moderately developed.A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3)The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects,and it is poorly preserved.The DY2 well is located far from the Qiyueshan Fault.Large faults are absent,and upward fractures in the Longmaxi Formation are poorly developed.The well is affected by low tectonic deformation intensity,and it is well preserved.(4)The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning.The thickness of the high-quality shale interval(WF2-LM4)is relatively small,which may be an important reason for the unstable production of shale gas thus far.Based on the systematic analysis of the geological factors controlling high-yield shale gas enrichment in the Dingshan area,and the comparative analysis with the surrounding typical exploration areas,the geological understanding of marine shale gas enrichment in southern China has been improved.Therefore,this study can provide a useful reference for shale gas exploration and further development.

陆缘地壳背景下白云凹陷油气差异成藏条件研究

珠江口盆地位于南海北部陆缘,地壳厚度从北侧的29 km向南部迅速减薄至17~18 km,海水深度从北部的<0.1 km向南增至>2 km,白云凹陷正处于盆地南部的陆缘地壳强烈薄化带深水区,受此影响,白云凹陷具有特殊的油气成藏条件。一是受壳幔级拆离断裂控制而发育形成大型宽深断陷,最大沉积地层厚度超过10 km,沉积面积超2×10^(4) km^(2);二是发育高变地温场,地温梯度从凹陷北部的3.5℃/100 m向南最高升至8.5℃/100 m,平均达5℃/100 m,高地温使得烃源岩热演化加速,储层快速致密;三是发育浅水及深水、陆相及海相沉积储盖组合;四是白云凹陷裂陷期发育多个生烃洼陷,每个生烃洼陷,烃源岩发育规模不同、环境不同,热演化程度不同,导致生成的油气规模和相态的差异。众多地质条件的差异,导致同一洼陷,甚至同一洼陷不同构造部位的油气成藏条件都存在较大差异,由此造成油气分布及富集程度的差异。本文通过对白云凹陷各成藏条件的精细分析,明确其在区域上的分布特征,进而指出不同区带油气富集主控因素,为白云凹陷下一步勘探提供参考和依据。