HRB600级钢筋混凝土柱偏压性能试验研究

为研究配置HRB600级钢筋混凝土柱的偏压性能,考虑偏心距与配筋率等因素影响,设计制作了6根高为2000mm的HRB600级钢筋C50混凝土柱。采用偏压加载的方式对试验柱进行静力试验,对其破坏形态、挠度曲线、极限承载力、钢筋强度设计值取值及裂缝宽度等展开研究,并对HRB600级钢筋混凝土柱纵向受拉、受压钢筋应变数据进行分析。研究成果显示:HRB600级钢筋混凝土偏压柱的受力形式以及破坏模式与普通钢筋混凝土偏压柱并无差异,其极限承载力仍然可以按照《混凝土结构设计规范》(GB 50010—2010)(2015年版)公式进行计算,但限定混凝土相对受压区高度x≥3.2a′s(a′s为受压区纵筋合力点至截面边缘的距离);对于此类偏压柱,建议HRB600级钢筋的屈服强度标准值取600MPa,抗拉强度设计值取520MPa,抗压强度设计值取460MPa;HRB600级钢筋混凝土柱最大裂缝宽度实测值与规范理论计算值在正常使用阶段吻合良好。

Evaluating the hydrocarbon generation potential of the Paleocene–Eocene carbonaceous rocks in the Barmer and Bikaner-Nagaur Basins, western Rajasthan, India

The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale deposits.The present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical tools.The carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis results.The existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)macerals.However,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic macerals.Apart from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of oil.This immaturity level in the studied outcrop section is due to the shallow burial depth.Geochemical proxies further indicate the presence of both oil and gas-prone source rocks.

Φ50mm直条HRB635E高强钢筋的开发与生产工艺优化

鄂城钢铁钢轧厂为积极开拓市场,全力推进大规格高强钢筋HRB635E的新产品开发工作。在追求产品创新的同时,兼顾降本增效的实际需求。通过精心研发和严谨测试,合理设计了Φ50mmHRB635E坯料的化学成分、加热温度及成品孔尺寸等关键参数。经过不断优化生产工艺,最终生产出的Φ50mm直条HRB635E高强钢筋,其性能成功达到了670-680MPa的高标准,不仅性能卓越、完全达标,而且表面质量也达到了优质水平,充分展现了鄂城钢铁钢轧厂的技术实力和市场竞争力。

超高性能混凝土(UHPC)与HRB600级钢筋黏结锚固性能研究

以山东省某超高层商业建筑为研究对象,运用室内试验的方法制作UHPC与HBR600钢筋黏结锚固件,研究钢筋的中心拉拔破坏过程,分析锚固可靠度。研究结果表明,UHPC与HRB600级钢筋的中心拉拔试验破坏过程大致可划分为荷载位移增长阶段、峰值拉拔阶段、破坏拔出阶段,拉拔过程与锚固区的界面应力状态和黏结强度密切相关;UHPC与HRB600钢筋的黏结应力与滑移曲线呈初始小位移的黏结应力快速增加,达到峰值后,黏结应力快速降低,并在位移达到6mm后,黏结应力下降速率有所降低;随着HRB600钢筋直径的增加,试件中心拉拔试验峰值黏结应力呈现一致的变化规律,均表现为增加后降低,在钢筋直径为20mm试件的中心拉拔试验峰值黏结应力最大;钢筋峰值拉应力随着HRB600钢筋直径的增加呈现先增加后降低的变化趋势,在钢筋直径为20mm,钢筋的峰值拉应力最大,但钢筋直径为22mm和25mm的峰值拉应力较为接近。

HRB500级钢筋在超高层建筑中的应用研究

HRB500级钢筋屈服强度高、力学性能卓越,它的应用不仅能够减少钢筋的使用量,降低工程的初期投入和总体成本,还能显著优化梁柱节点处钢筋密集的问题。依托于广州市某项目超过200 m的两栋超高层建筑,拆分成了6个不同高度且大于150 m的模型,进一步分别采用HRB500、HRB400级钢筋进行了计算分析,并从钢筋用量、钢筋造价等方面进行了对比研究。超高层建筑中采用HRB500级钢筋能得到相对较好的经济和环保效益,为类似工程的应用提供了参考。

Mesozoic multi-direction collision tectonic evolution of the Ordos Basin, China: Insights from the detrital zircon and apatite (U-Th)/He analyses

The Ordos Basin(OB)in the western part of the North China Craton(NCC),was located at the jointed area of multi-plates and has recorded the Mesozoic tectonic characteristics.Its tectonic evolution in the Mesozoic is significant to understand the tectonic transformation of the northern margin of the NCC.In this work,the detrital zircon and apatite(U-Th)/He chronological system were analyzed in the northern part of the OB,and have provided new evidence for the regional tectonic evolution.The(U-Th)/He chronological data states the weighted ages of 240‒235 Ma,141 Ma with the peak distribution of 244 Ma,219 Ma,173 Ma,147‒132 Ma.The thermal evolution,geochronological data,and regional unconformities have proved four stages of regional tectonic evolution for the OB and its surroundings in the Mesozoic:(1)The Late Permian-Early Triassic;(2)the Late Triassic-Early Jurassic;(3)the Late Jurassic-Early Cretaceous;(4)the Late Cretaceous-Early Paleogene.It is indicated that the multi-directional convergence from the surrounding tectonic units has controlled the Mesozoic tectonic evolution of the OB.Four-stage tectonic evolution reflected the activation or end of different plate movements and provided new time constraints for the regional tectonic evolution of the NCC in the Mesozoic.

Chemical weathering in Manas River Basin:Driven by sulfuric acid or carbonic acid?

Carbonic acid produced by the dissolution of atmospheric and soil CO_(2)in water is usually the most dominant catalyst for chemical weathering,but a sulfuric aciddriven phenomenon,different from usual,was found in the orogenic belt watersheds dominated by silicate bedrock.This study,rooted in comprehensive field investigations in the Manas River Basin(MRB)north of the Tianshan Mountains,delves into the mechanisms and impacts of sulfuric and carbonic acid as catalysts driving diff erent types of chemical weathering in the Central Asian Orogenic Belt.Quantitative analyses elucidate that carbonate weathering constitutes 52.4%of the total chemical weathering,while silicate and evaporite account for 18.6%and 25.3%,respectively,with anthropogenic activities and atmospheric precipitation having little eff ect.The estimated total chemical weathering rate in MRB is approximately 0.075×10^(6)mol/km^(2)/year.Quantitative findings further suggest that,preceding carbonate precipitation(<10^(4)year),chemical weathering can absorb CO_(2).Subsequently,and following carbonate precipitation(10^(4)-10^(7)year),it will release CO_(2).The release significantly surpasses the global average CO_(2)consumption,contributing to a noteworthy climate impact.This study underscores the distinctive weathering mechanisms,wherein sulfuric acid emerges as the predominant catalyst.The quantity of sulfuric acid as a catalyst is approximately three times that of carbonic acid.Sulfuric acid-driven carbonate rock weathering(SCW)is identified as the sole chemical weathering type with a net CO_(2)release eff ect.SCW CO_(2)release flux(5176 mol/km^(2)/year)is roughly 2.5 times the CO_(2)absorption by Ca-Mg silicate weathering,highlighting the pivotal role of chemical weathering in sourcing atmospheric CO_(2)over the timescales of carbonate precipitation and sulfate reduction.Lastly,this study posits that catalyst and transport limitations are the most plausible critical factors in MRB.The interplay between sulfuric acid and dissolved CO_(2)competitively shapes the types and rates of chemical weathering reactions.

Dynamic Variation of Vegetation NPP and Its Driving Forces in the Yellow River Basin, China

The productivity of vegetation is influenced by both climate change and human activities.Understanding the specific contributions of these influencing factors is crucial for ecological conservation and regional sustainability.This study utilized a combination of multi-source data to examine the spatiotemporal patterns of Net Primary Productivity(NPP)in the Yellow River Basin(YRB),China from 1982 to 2020.Additionally,a scenario-based approach was employed to compare Potential NPP(PNPP)with Actual NPP(ANPP)to determine the relative roles of climatic and human factors in NPP changes.The PNPP was estimated using the Lund-Potsdam-Jena General Ecosystem Simulator(LPJ-GUESS)model,while ANPP was evaluated by the Carnegie-Ames-Stanford Approach(CASA)model using different NDVI data sources.Both model simulations revealed that significant greening occurring in the YRB,with a gradual decrease observed from southeast to northwest.According to the LPJ_GUESS model simulations,areas experiencing an increasing trend in NPP accounted for 86.82% of the YRB.When using GIMMS and MODIS NDVI data with CASA model simulations,areas showing an increasing trend in NPP accounted for 71.42% and 97.02%,respectively.Furthermore,both climatic conditions and human factors had positive effects on vegetation restoration;approximated 41.15% of restored vegetation areas were influenced by both climate variation and human activities,while around 31.93% were solely affected by climate variation.However,it was found that human activities served as the principal driving force of vegetation degradation within the YRB,impacting 26.35% of degraded areas solely due to human activities.Therefore,effective management strategies encompassing both human activities and climate change adaptation are imperative for facilitating vegetation restoration within this region.These findings will valuable for enhancing our understanding in NPP changes and its underlying factors,thereby contributing to improved ecological management and the pursuit of regional carbon neutrality in China.

Carboniferous-Early Permian heterogeneous distribution of porous carbonate reservoirs in the Central Uplift of the South Yellow Sea Basin and its hydrocarbon potential analysis

Mesozoic-Palaeozoic marine carbonate rocks are crucial hydrocarbon reservoirs in the Central Uplift area of the South Yellow Sea Basin(SYSB).Due to the scarcity of boreholes and the significant heterogeneity of carbonate reservoirs,the distribution of porous carbonate reservoirs and their related key controlling factors remain unclear.In this study,factors affecting the distribution of porous Carboniferous-Early Permian carbonate reservoirs in the SYSB were investigated through seismic inversion and isotope analysis.The log-seismic characteristics of porous carbonate reservoirs,sensitive lithology parameters,and physical property parameters were extracted and analyzed.The pre-stack simultaneous inversion technique was applied to predict the lithology and physical properties of porous carbonate reservoirs.Moreover,the sedimentary of carbonate was analyzed using isotopes of carbon,oxygen,and strontium.The results show that porous carbonate reservoirs are mainly developed in the open platform sediments with porosities of 3%-5%and are mainly distributed in the paleo-highland(Huanglong Formation and Chuanshan Formation)and the slope of paleo-highland(Hezhou Formation).The porous carbonate reservoirs of the Qixia Formation are only locally developed.In addition,the negativeδ13C excursions indicate a warm and humid tropical climate with three sea-level fluctuations in the study area from the Carboniferous to Early Permian.The favorable conditions for developing porous carbonate rocks include the sedimentary environment and diagenetic process.The primary pore tends to form in high-energy environments of the paleo-highland,and the secondary pore is increased by dissolution during the syngenetic or quasi-syngenetic period.According to the hydrocarbon potential analysis,the Late Ordovician Wufeng Formation and Lower Silurian Gaojiabian Formation are the source rocks in the high-maturity-over-maturity stage,the Carboniferous-Lower Permian carbonate is the good reservoirs,and the Late Permian Longtan-Dalong Formation is the stable seal,ensuring a huge hydrocarbon accumulation potential in SYSB.The methods proposed in this study can be applied to other carbonate-dominated strata worldwide.

Runoff simulation and hydropower resource prediction of the Kaidu River Basin in the Tianshan Mountains,China

The Tianshan Mountains of Central Asia,highly sensitive to climate change,has been comprehensively assessed for its ecosystem vulnerability across multiple aspects.However,studies on the region's main river systems and hydropower resources remain limited.Thus,examining the impact of climate change on the runoff and gross hydropower potential(GHP)of this region is essential for promoting sustainable development and effective management of water and hydropower resources.This study focused on the Kaidu River Basin that is situated above the Dashankou Hydropower Station on the southern slope of the Tianshan Mountains,China.By utilizing an ensemble of bias-corrected global climate models(GCMs)from Coupled Model Intercomparison Project Phase 6(CMIP6)and the Variable Infiltration Capacity(VIC)model coupled with a glacier module(VIC-Glacier),we examined the variations in future runoff and GHP during 2017-2070 under four shared socio-economic pathway(SSP)scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5)compared to the baseline period(1985-2016).The findings indicated that precipitation and temperature in the Kaidu River Basin exhibit a general upward trend under the four SSP scenarios,with the fastest rate of increase in precipitation under the SSP2-4.5 scenario and the most significant changes in mean,maximum,and minimum temperatures under the SSP5-8.5 scenario,compared to the baseline period(1980-2016).Future runoff in the basin is projected to decrease,with rates of decline under the SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5 scenarios being 3.09,3.42,7.04,and 7.20 m^(3)/s per decade,respectively.The trends in GHP are consistent with runoff,with rates of decline in GHP under the SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5 scenarios at 507.74,563.33,1158.44,and 1184.52 MW/10a,respectively.Compared to the baseline period(1985-2016),the rates of change in GHP under the SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5 scenarios are-20.66%,-20.93%,-18.91%,and-17.49%,respectively.The Kaidu River Basin will face significant challenges in water and hydropower resources in the future,underscoring the need to adjust water resource management and hydropower planning within the basin.

氯盐环境下钢筋HRB400的腐蚀行为与力学性能研究

为了给工程安全使用提供借鉴,采用浸泡腐蚀法研究钢筋HRB400在3.5%NaCl溶液中裸露和镶入混凝土2种环境下腐蚀行为及腐蚀后的力学性能,对于钢筋HRB400镶入混凝土这种环境,采用制作钢筋混凝土及模拟混凝土孔隙液2种方法,首先将裸露和镶入混凝土2种情况下的钢筋HRB400浸泡在3.5%(质量分数)NaCl溶液中,并将钢筋HRB400浸泡在饱和氢氧化钙溶液中[加入3.5%(质量分数)NaCl溶液],然后分别计算不同腐蚀时间下各钢筋HRB400相应的失重率、腐蚀率,最后采用MTS试验机测试钢筋HRB400腐蚀后的力学性能。结果显示:随着浸泡腐蚀时间延长,3种环境下的钢筋HRB400平均腐蚀速率逐渐降低,失重率增加,屈服强度、抗拉强度均下降,钢筋HBR400在3.5%NaCl溶液中裸露或镶入混凝土时伸长率随浸泡时间延长而降低,在饱和氢氧化钙(加入3.5%NaCl)中则呈现有升有降趋势。

HRB635级高强钢筋与C70高强混凝土黏结锚固性能试验研究

目的 研究HRB635级高强钢筋与C70高强混凝土之间黏结锚固性能,为工程应用提供参考。方法 设计制作了5组45个直锚试件进行拉拔试验,分析了锚固长度、配箍率、混凝土保护层厚度等因素对锚固性能的影响。结果 试件极限承载力随配箍率和锚固长度的增加而增加,但当箍筋率ρsv大于1.26%,锚固长度la大于15d后,配箍率和锚固长度的增加不再对试件极限承载力产生明显的影响;对于未配置箍筋的试件,当试件保护层厚度从2d增加到3d时,试件极限承载力随着保护层厚度的增加而增加,但当保护层厚度大于3d后,保护层厚度的增加对试件极限承载力基本没有影响。结论 在进行HRB635级高强钢筋和C70高强混凝土试件设计时,锚固长度可按《混凝土结构设计规范》(GB 50010-2010)中相关公式进行计算,且具有足够的安全储备。

镧铈混合稀土和开轧温度对HRB400E钢组织及耐蚀性的影响

为了改善HRB400E钢的耐蚀性能,在精炼过程向钢中加入镧铈混合稀土合金,控制开轧温度对试验钢进行轧制。采用扫描电镜、能谱仪和光学金相显微镜对夹杂物和显微组织进行表征,结合中性盐雾腐蚀试验,分析稀土和开轧温度对试验钢耐蚀性的影响。结果表明,经镧铈混合稀土处理后,Mn-Si-O夹杂物被完全转变为(Ce,La)_(2)O_(3)和(Ce,La)_(2)O_(2)S,部分Mn和S在其周围形核生成稀土复合夹杂物,仍有少量单独MnS析出。在试验条件下,开轧温度为900℃、混合稀土含量为0.0116%的2^(#)试验钢腐蚀速率为1.577 g/(m^(2)·h),耐蚀性能最佳。

HRB600钢筋钢纤维混凝土梁受弯承载力试验研究

将钢纤维掺入到HRB600高强钢筋混凝土梁中,可以有效改善HRB600高强钢筋混凝土梁的受弯力学性能。通过改变钢纤维体积率、钢纤维混凝土强度和纵筋配筋率,研究了7根HRB600钢筋混凝土梁的受弯性能,以及各试件的破坏形态、跨中挠度和纵筋应变随钢纤维体积率、钢纤维混凝土强度和纵筋配筋率的变化规律,探讨了受弯承载力的计算方法。结果表明:HRB600钢筋钢纤维混凝土梁的受弯力学性能与普通钢筋混凝土梁相似,截面应变分布符合平截面假定,受弯承载力随着钢纤维体积率、钢纤维混凝土强度以及配筋率的增加而增大,其中钢纤维掺量的提升幅度比钢纤维混凝土强度明显。普通钢筋钢纤维混凝土梁的正截面受弯承载力公式同样可用于HRB600高强钢筋钢纤维混凝土梁的受弯承载力计算,受弯承载力实测值与计算值吻合较好。

配置HRB635高强钢筋的混凝土梁受弯性能试验研究

对11根配置HRB635高强钢筋的足尺混凝土梁进行受弯性能试验,研究了配置HRB635高强钢筋梁的受力过程、破坏模式以及承载力和变形能力,并评估了我国混凝土规范中受弯构件受弯承载力和最大裂缝宽度计算公式在高强钢筋混凝土梁中的适用性。试验结果表明:配置HRB635高强钢筋的混凝土梁受力性能和破坏形态与普通钢筋混凝土梁基本一致,均为高强钢筋首先受拉屈服,最后受压区混凝土压碎破坏,高强钢筋的强度能够充分发挥;根据我国混凝土规范计算得到的试验梁的极限弯矩值与实测值之间较为接近,说明高强钢筋梁的正截面受弯承载力仍可按现行混凝土规范进行计算;正常使用极限状态下试验梁的最大裂缝宽度均超过了短期荷载作用下受弯构件的裂缝宽度限值,说明高强钢筋梁的设计存在由正常使用极限状态而非承载能力极限状态控制的情况;按照混凝土规范中最大裂缝宽度的计算公式计算结果与实测结果差别不大,计算值略大于实测值。

Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,China:Insights from continental scientific drilling

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been weak.Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different strata.The gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary environment.With increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to inorganic.The origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and mantle-derived.The shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic gas.Furthermore,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas.The discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

Spatio-temporal Variation Characteristics of Extreme Climate Events and Their Teleconnections to Large-scale Ocean-atmospheric Circulation Patterns in Huaihe River Basin,China During 1959–2019

Huaihe River Basin(HRB) is located in China’s north-south climatic transition zone,which is very sensitive to global climate change.Based on the daily maximum temperature,minimum temperature,and precipitation data of 40 meteorological stations and nine monthly large-scale ocean-atmospheric circulation indices data during 1959–2019,we present an assessment of the spatial and temporal variations of extreme temperature and precipitation events in the HRB using nine extreme climate indices,and analyze the teleconnection relationship between extreme climate indices and large-scale ocean-atmospheric circulation indices.The results show that warm extreme indices show a significant(P < 0.05) increasing trend,while cold extreme indices(except for cold spell duration) and diurnal temperature range(DTR) show a significant decreasing trend.Furthermore,all extreme temperature indices show significant mutations during 1959-2019.Spatially,a stronger warming trend occurs in eastern HRB than western HRB,while maximum 5-d precipitation(Rx5day) and rainstorm days(R25) show an increasing trend in the southern,central,and northwestern regions of HRB.Arctic oscillation(AO),Atlantic multidecadal oscillation(AMO),and East Atlantic/Western Russia(EA/WR) have a stronger correlation with extreme climate indices compared to other circulation indices.AO and AMO(EA/WR) exhibit a significant(P < 0.05) negative(positive)correlation with frost days and diurnal temperature range.Extreme warm events are strongly correlated with the variability of AMO and EA/WR in most parts of HRB,while extreme cold events are closely related to the variability of AO and AMO in eastern HRB.In contrast,AMO,AO,and EA/WR show limited impacts on extreme precipitation events in most parts of HRB.

Fossil Equidae in the Linxia Basin with Biostratigraphic and Paleozoogeographic Significance

The Linxia Basin is characterized by an abundance of Cenozoic sediments,that contain exceptionally rich fossil resources.Equids are abundant in the Linxia Basin,the fossil record of equids in this region including 16 species that represent 10 genera.In comparison to other classic late Cenozoic areas in China,the Linxia Basin stands out,because the fauna and chronological data accompanying Linxia equids render them remarkably useful for biostratigraphy.The anchitheriines in the region,such as Anchitherium and Sinohippus,represent early equids that appeared in the late stages of the middle and late Miocene,respectively.Among the equines,most species of Chinese hipparions have been identified in the Linxia Basin and some species of the genera Hipparion and Hippotherium have FAD records for China.Furthermore,Equus eisenmannae is one of the earliest known species of Equus in the Old World and is well-represented at the Longdan locality.Some species with precise geohistorical distributions can serve as standards for high-resolution chronological units within this framework.Located at the eastern margin of the Tibetan Plateau and subject to considerable uplift,the Linxia Basin has served as a biogeographic transition area for equids throughout the late Cenozoic.

Geochemical characteristics and exploration significance of ultra-deep Sinian oil and gas from Well Tashen 5,Tarim Basin,NW China

The Well Tashen 5(TS5),drilled and completed at a vertical depth of 9017 m in the Tabei Uplift of the Tarim Basin,NW China,is the deepest well in Asia.It has been producing both oil and gas from the Sinian at a depth of 8780e8840 m,also the deepest in Asia in terms of oil discovery.In this paper,the geochemical characteristics of Sinian oil and gas from the well were investigated and compared with those of Cambrian oil and gas discovered in the same basin.The oil samples,with Pr/Ph ratio of 0.78 and a whole oil carbon isotopic value of31.6‰,have geochemical characteristics similar to those of Ordovician oils from the No.1 fault in the North Shuntuoguole area(also named Shunbei area)and the Middle Cambrian oil from wells Zhongshen 1(ZS1)and Zhongshen 5(ZS5)of Tazhong Uplift.The maturity of light hydrocarbons,diamondoids and aromatic fractions all suggest an approximate maturity of 1.5%e1.7%Ro for the samples.The(4-+3-)methyldiamantane concentration of the samples is 113.5 mg/g,indicating intense cracking with a cracking degree of about 80%,which is consistent with the high bottom hole temperature(179℃).The Sinian gas samples are dry with a dryness coefficient of 0.97.The gas is a mixture of kerogen-cracking gas and oil-cracking gas and has Ro values ranging between 1.5%and 1.7%,and methane carbon isotopic values of41.6‰.Based on the equivalent vitrinite reflectance(R_(eqv)=1.51%e1.61%)and the thermal evolution of source rocks from the Cambrian Yu'ertusi Formation of the same well,it is proposed that the Sinian oil and gas be mainly sourced from the Cambrian Yu'ertusi Formation during the Himalayan period but probably also be joined by hydrocarbon of higher maturity that migrated from other source rocks in deeper formations.The discovery of Sinian oil and gas from Well TS5 suggests that the ancient ultra-deep strata in the northern Tarim Basin have the potential for finding volatile oil or condensate reservoirs.

Geological characteristics and exploration breakthroughs of coal rock gas in Carboniferous Benxi Formation,Ordos Basin,NW China

To explore the geological characteristics and exploration potential of the Carboniferous Benxi Formation coal rock gas in the Ordos Basin,this paper presents a systematic research on the coal rock distribution,coal rock reservoirs,coal rock quality,and coal rock gas features,resources and enrichment.Coal rock gas is a high-quality resource distinct from coalbed methane,and it has unique features in terms of burial depth,gas source,reservoir,gas content,and carbon isotopic composition.The Benxi Formation coal rocks cover an area of 16×104km^(2),with thicknesses ranging from 2 m to 25 m,primarily consisting of bright and semi-bright coals with primitive structures and low volatile and ash contents,indicating a good coal quality.The medium-to-high rank coal rocks have the total organic carbon(TOC)content ranging from 33.49%to 86.11%,averaging75.16%.They have a high degree of thermal evolution(Roof 1.2%-2.8%),and a high gas-generating capacity.They also have high stable carbon isotopic values(δ13C1of-37.6‰to-16‰;δ13C2of-21.7‰to-14.3‰).Deep coal rocks develop matrix pores such as gas bubble pores,organic pores,and inorganic mineral pores,which,together with cleats and fractures,form good reservoir spaces.The coal rock reservoirs exhibit the porosity of 0.54%-10.67%(averaging 5.42%)and the permeability of(0.001-14.600)×10^(-3)μm^(2)(averaging 2.32×10^(-3)μm^(2)).Vertically,there are five types of coal rock gas accumulation and dissipation combinations,among which the coal rock-mudstone gas accumulation combination and the coal rock-limestone gas accumulation combination are the most important,with good sealing conditions and high peak values of total hydrocarbon in gas logging.A model of coal rock gas accumulation has been constructed,which includes widespread distribution of medium-to-high rank coal rocks continually generating gas,matrix pores and cleats/fractures in coal rocks acting as large-scale reservoir spaces,tight cap rocks providing sealing,source-reservoir integration,and five types of efficient enrichment patterns(lateral pinchout complex,lenses,low-amplitude structures,nose-like structures,and lithologically self-sealing).According to the geological characteristics of coal rock gas,the Benxi Formation is divided into 8 plays,and the estimated coal rock gas resources with a buried depth of more than 2000 m are more than 12.33×10^(12)m^(3).The above understandings guide the deployment of risk exploration.Two wells drilled accordingly obtained an industrial gas flow,driving the further deployment of exploratory and appraisal wells.Substantial breakthroughs have been achieved,with the possible reserves over a trillion cubic meters and the proved reserves over a hundred billion cubic meters,which is of great significance for the reserves increase and efficient development of natural gas in China.