二叠系火山碎屑岩气藏天然气地球化学特征及气源分析——以四川盆地成都—简阳地区永探1井为例

2018年12月底,在四川盆地二叠系火山岩发育地区部署的风险探井永探1井测试获得22.5万m³/d的高产工业气流,实现了二叠系火山碎屑岩的重大勘探突破,展现了火山碎屑岩气藏的巨大勘探潜力。本文根据该钻井成果资料,应用分析化验数据,采用不同地区气-气对比方法,开展了成都—简阳地区天然气地球化学特征分析、源-储接触关系解剖及气源综合对比。在此基础上,对二叠系火山碎屑岩气藏天然气成因进行了鉴别,对天然气来源进行了判识。结果表明：永探1井火山岩气藏天然气均为典型的干气,干燥系数达0.997,CH₄质量分数高,平均为99.03%,C₂H₆质量分数低,平均为0.35%,C₃H₈几乎没有,不含H₂S;天然气甲烷、乙烷碳同位素值均较轻,甲烷碳同位素平均值为-32.17‰,乙烷碳同位素平均值为-34.27‰,且岩心及镜下可见大量残余沥青,天然气成因鉴别分析表明永探1井火山岩气藏天然气为原油二次裂解气;通过源-储接触关系解剖以及天然气甲烷、乙烷碳同位素对比分析,表明永探1井火山碎屑岩气藏天然气主要来源于德阳—安岳台内裂陷内发育的巨厚下寒武统筇竹寺组优质烃源岩,部分来源于中二叠统。     

2015—2019年辽宁省暴雨红色预警信号分布及其特征

利用2015—2019年辽宁省发布的暴雨红色预警信号和1605个自动站的分钟级降水资料,统计暴雨红色预警信号和短时大暴雨年际变化和时空分布,分析暴雨红色预警信号的高分布区、易发时段。结果表明：2015—2017年辽宁省暴雨红色预警信号发布站数逐年递增,最大值出现在2017年,发布站数为147个;2015—2018年预警信号准确率提升,提前时间略减少,最低值为2018年,提前时间为19 min;2019年比2018年暴雨红色预警信号发布站数减少59个,提前时间增加29 min;暴雨红色预警信号的空间分布为东南部地区多、中部地区少;暴雨红色预警信号多在夜间发布;在辽宁省发布的50%以上的暴雨红色预警信号中,降水量达到预警发布标准的时间滞后于最大雨强出现时间90 min,最大雨强出现时间为暴雨红色预警信号发布的重要指标。为了达到防灾减灾的服务效果,发布暴雨红色预警信号时,应充分考虑最大雨强出现时间、发布时机、短时大暴雨高发区及地形的影响。     

晚新生代洛川典型风尘堆积序列的延伸

对中国黄土标准剖面———洛川黄土剖面之下的上新世红黏土进行了沉积特征和磁性地层学的研究,结果表明洛川红黏土堆积于约2.6~3.2 MaBP期间,从而确定世界惟一的黄土类地质公园的风尘开始堆积的年代约为3.2 MaBP。古气候替代性指标磁化率和粒度的分析表明,洛川风尘堆积序列记录了上新世到第四纪古气候的重大转型。     

不同压实度下红层泥岩路堤沉降研究

压实系数是控制路堤填筑的关键性指标。本文通过分析不同压实系数下的强度特点以及通过离心试验和有限元对不同压实系数路堤沉降的模拟,得到粘聚力c值和摩擦角与不同压实系数的关系以及不同压实系数下路堤沉降的特点,为路堤填筑提供了重要的依据。     

红河断裂活动对琼东南盆地环崖南凹陷构造-沉积-成藏的影响

琼东南盆地西部环崖南凹陷的油气勘探亟需寻找接替领域.针对勘探研究中存在的3个地质问题,利用丰富的钻井和地震资料对红河断裂活动特征及其对环崖南凹陷构造-沉积-成藏的影响开展深入分析.认为红河断裂的走滑活动通过F1断层向琼东南盆地西部传递剪切应力,其演化与环崖南凹陷的构造-沉积作用具有良好的时空耦合关系,并控制了环崖南凹陷...     

Analysis of petroleum hydrocarbons in mangrove sediments of Red Sea of Yemen

A field work has been carried out to identify the occurrence of oil and oil products pollution in mangrove sediment from Red Sea of Yemen. The concentration of total petroleum hydrocarbons is from 700 ng/g at Kamaran Island station to 400 ng/g at Al-Hodiedah station, and the total organic carbon ( TOC) in samples ranges from 0.07% at Dhubab station to 0.03% at Kamaran Island station. This pollution is as a result of localized oil pollution and /or heavy ship traffic in the Red Sea and Gulf of Aden.     

Optical properties of the red tide in Isahaya Bay,southwestern Japan: Influence of chlorophyll a concentration

Remote sensing reflectance [R _rs(λ)] and absorption coefficients of red tides were measured in Isahaya Bay, southwestern Japan, to investigate differences in the optical properties of red tide and non-red tide waters. We defined colored areas of the sea surface, visualized from shipboard, as “red tides”. Peaks of the R _rs(λ) spectra of non-red tide waters were at 565 nm, while those of red tides shifted to longer wavelengths (589 nm). The spectral shape of R _rs(λ) was close to that of the reciprocal of the total absorption coefficient [1/a(λ)], implying that the R _rs(λ) peak is determined by absorption. Absorption coefficients of phytoplankton [a _ph(λ)], non-pigment particles and colored dissolved organic matter increased with increasing chlorophyll a concentration (Chl a), and those coefficients were correlated with Chl a for both red tide and non-red tide waters. Using these relationships between absorption coefficients and Chl a, variation in the spectrum of 1/a(λ) as a function of Chl a was calculated. The peak of 1/a(λ) shifted to longer wavelengths with increasing Chl a. Furthermore, the relative contribution of a _ph(λ) to the total absorption in red tide water was significantly higher than in non-red tide water in the wavelength range 550–600 nm, including the peak. Our results show that the variation of a _ph(λ) with Chl a dominates the behavior of the R _rs(λ) peak, and utilization of R _rs(λ) peaks at 589 and 565 nm may be useful to discriminate between red tide and non-red tide waters by remote sensing.     

Fundamental study for morphodynamic modelling: Sand mounds in oscillatory flows

Experiments on sand mounds in oscillatory flow, undertaken in controlled, large-scale laboratory conditions, have produced well-defined data sets for model comparison. Three bathymetries with different levels of submergence, including a surface-piercing case, were tested. The maximum slope was about 1:5.5. Sediment transport is due to bed load with ripple formation. The principal time-dependent bulk parameters are the vertical distance of the centre of gravity above the base and the volume of the mound. A semi-implicit finite-volume depth-averaged hydrodynamic model is used to drive morphodynamics, using van Rijn's sediment flux model generalized to take account of bed slope, and some justification is given for depth-averaged modeling in these conditions. Starting the model runs with the conditions at the end of the first cycle avoided initial atypical physical behaviour. In general good predictions were obtained with an angle of repose reduced from the standard value of about 30° for stationary beds to 15°. For these situations, morphodynamics was largely unaffected by a hydrodynamic roughness height in the range 2.5D₅₀ to 51D₅₀, with larger values accounting for ripple roughness. The reduced angle of repose may be physically expected with mobile beds but this specific value is only expected to be suited to this form of bed motion. In one case an exaggerated ripple formed near the top of the mound reducing agreement with experiment. For the submerged case with normal ripple structure excellent predictions were obtained. For the initially surface-piercing mound, the time of submergence was better predicted with a 30° angle of repose, presumably due to the prominent influence of the near stationary bed near the wet/dry interface, although long term predictions were better predicted with 15°. The occurrence of vortex shedding in the first cycle modeled was in agreement with experimental observation.     

Analysis of petroleum hydrocarbons in mangrove sediments of Red Sea of Yemen

A field work has been carried out to identify the occurrence of oil and oil products pollution in mangrove sediment from Red Sea of Yemen. The concentration of total petroleum hydrocarbons is from 700ng/g at Kamaran Island station to 400 ng/g at Al-Hodiedah station, and the total organic carbon （TOC） in samples ranges from 0. 07% at Dhubab station to 0. 03% at Kamaran Island station. This pollution is as a result of localized oil pollution and/or heavy ship traffic in the Red Sea and Gulf of Aden.     

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