珠江口盆地西江主洼油气差异分布机制

西江主洼是珠江口盆地一个低勘探程度洼陷，油气差异聚集特征明显，但其机理不清。本文在断陷盆地油气成藏理论指导下，利用研究区地质、地球物理和地球化学等资料，开展了烃源岩、断盖组合、储集体系和运聚模式等方面的研究。结果表明，裂陷期沉降、沉积中心有序迁移，造成主力烃源岩自东向西由文四段迁移至文三段、文一+二段，控制东、西部油气差异分布。恩平组区域性泥岩发育且晚期断裂缺乏，导致油气纵向上更易聚集于下构造层；区域泥岩减薄尖灭或晚期断裂切开盖层的区域，上构造层有一定油气分布。"源-汇"类型从宏观上控制储层优劣，影响下构造层油气富集程度；"仓储"运移是控制上构造层油气规模聚集的主要模式。下构造层古近系应作为重点部署方向，东部围绕文四段、西部围绕文三段、文一+二段烃源岩构成的含油气系统展开；上构造层勘探需关注珠海组，在隆起周边寻找具备"仓储"运移模式的有利区带。     

Effects of Enclosure on Plant and Soil Nutrients in Different Types of Alpine Grassland

Enclosure is one of the most widely used management tools for degraded alpine grassland on the northern Tibetan Plateau, but the responses of different types of grassland to enclosure may vary, and research on these responses can provide a scientific basis for improving ecological conservation. This study took one site for each of three grassland types (alpine meadow, alpine steppe and alpine desert) on the northern Tibetan Plateau as examples, and explored the effects of enclosure on plant and soil nutrients by comparing differences in plant community biomass, leaf-soil nutrient content and their stoichiometry between samples from inside and outside the fence. The results showed that enclosure can significantly increase all aboveground biomass in these three grassland types, but it only increased the 10-20 cm underground biomass in the alpine desert. Enclosure also significantly increased the leaf nutrient content of the dominant plants and contents of total nitrogen (N), total potassium (K), and organic carbon (C) in 10-20 cm soil in alpine desert, thus changing the stoichiometry between C, N and P (phosphorus). However, enclosure significantly increased only the N content of dominant plant leaves in alpine steppe, while other nutrients and stoichiometries of both plant leaves and soil did not show significant differences in alpine meadow and alpine steppe. These results suggested that enclosure has differential effects on these three types of alpine grasslands on the northern Tibetan Plateau, and the alpine desert showed the most active ecological conservation in the responses of its soil and plant nutrients.     

基于COS-2S模型的ADCP海浪方向谱估计

美国RD公司声学多普勒流速剖面仪(ADCP)使用的波向估计算法是迭代的最大似然算法(IMLM),IMLM可以准确估计出主浪向,但波向估计结果在主浪向以外其他方向上存在由噪声带来的能量分布,使得估计结果变得不准确。设计了基于COS-2S模型的波向估计方法,模型中只含有主波向,算法在准确估计主波向同时有效去除其他方向上噪声带来的能量分布。将一种混合遗传算法(HGA)代替遗传算法(GA)应用到波浪模型的参数求解中,HGA相对GA收敛更快,可有效找出全局最优解。仿真分析和实测数据表明,HGA和IMLM都能准确估计出波浪的主浪向,但HGA可有效去除主浪向以外其他方向上噪声带来的能量分布,HGA比IMLM更加适用于海洋各种噪声存在条件下的测量环境。     

Controlling factors on the charging process of oil and gas in the eastern main sub-sag of the Baiyun Sag,Zhujiang River (Pearl River) Mouth Basin

The eastern main sub-sag (E-MSS) of the Baiyun Sag was the main zone for gas exploration in the deep-water area of the Zhujiang River (Pearl River) Mouth Basin at its early exploration stage, but the main goal of searching gas in this area was broken through by the successful exploration of the W3-2 and H34B volatile oil reservoirs, which provides a new insight for exploration of the Paleogene oil reservoirs in the E-MSS. Nevertheless, it is not clear on the distribution of “gas accumulated in the upper layer, oil accumulated in the lower layer” (Gas_upper-Oil_lower) under the high heat flow, different source-rock beds, multi-stages of oil and gas charge, and multi-fluid phases, and not yet a definite understanding of the genetic relationship and formation mechanism among volatile oil, light oil and condensate gas reservoirs, and the migration and sequential charge model of oil and gas. These puzzles directly lead to the lack of a clear direction for oil exploration and drilling zone in this area. In this work, the PVT fluid phase, the origin of crude oil and condensate, the secondary alteration of oil and gas reservoirs, the evolution sequence of oil and gas formation, the phase state of oil and gas migration, and the configuration of fault activity were analyzed, which established the migration and accumulation model of Gas_upper-Oil_lower co-controlled by source and heat, and fractionation controlled by facies in the E-MSS. Meanwhile, the fractionation evolution model among common black reservoirs, volatile reservoirs, condensate reservoirs and gas reservoirs is discussed, which proposed that the distribution pattern of Gas_upper-Oil_lower in the E-MSS is controlled by the generation attribute of oil and gas from source rocks, the difference of thermal evolution, and the fractionation controlled by phases after mixing the oil and gas. Overall, we suggest that residual oil reservoirs should be found in the lower strata of the discovered gas reservoirs in the oil-source fault and diapir-developed areas, while volatile oil reservoirs should be found in the deeper strata near the sag with no oil-source fault area.     

Deep Structure and Dynamics of Passive Continental Margin from Shelf to Ocean of the Northern South China Sea

To study the deep dynamic mechanism leading to the difference in rifting pattern and basin structure from shelf to oceanic basin in passive continental margin,we constructed long geological sections across the shelf,slope and oceanic basin using new seismic data.Integrated gravity-magnetic inversion and interpretation of these sections were made with the advanced dissection method.Results show that the basement composition changes from intermediate-acid intrusive rocks in the sheff to intermediate-basic rocks in the slope.The Moho surface shoals gradually from 31 km in the sheff to 22.5 km in the uplift and then 19 km in the slope and finally to 13 km in the oceanic basin.The crust thickness also decreases gradually from 30 km in the northern fault belt to 9 km in the oceanic basin.The crustal stretching factor increases from the shelf toward the oceanic basin,with the strongest extension under the sags and the oceanic basin.The intensity of mantle upwelling controlled the style of basin structures from sheff to oceanic basin.In the Zhu 1 depression on the shelf,the crust is nearly normal,the brittle and cold upper crust mainly controlled the fault development;so the combinative grabens with single symmetric graben are characteristic.In the slope,the crust thinned with a large stretching factor,affected by the mantle upwelling.The ductile deformation controlled the faults,so there developed an asymmetric complex graben in the Baiyun (白云) sag.     

Characteristics and Hydrocarbon Potential of Mesozoic Strata in Eastern Pearl River Mouth Basin, Northern South China Sea

The well LF35-1-1 in the eastern Pearl River Mouth basin (PRMB) of the northern South China Sea revealed nnmetamorphosed Middle-Late Jurassic neritic-bathyal sediments and Cretaceous fluvial-lacustrine sediments.Three tectonic movements were identified in Late Jurassic to Early Cretaceous,late Early Cretaceous,and Late Cretaceous to Paleocene,respectively.The Late Jurassic marine facies mainly contain the hydrocarbon source and reservoir-seal assemblages,providing a main exploration target.     

锆石裂变径迹(ZFT)年代学:进展与应用

裂变径迹技术是解决各种与时间-温度相关的地质问题的一种低温年代学手段.与磷灰石相比,锆石裂变径迹具有较高的封闭温度和退火区间,有其特定的地质意义和应用.自20世纪90年代以来,开展了大量锆石裂变径迹退火的研究,包括退火特性、径迹测量、退火模型,以及来自露头和钻孔样品的退火研究.首先介绍了锆石裂变径迹的分析程序、测量标准...     

基于精确权函数的仪器响应失真校正方法与算例

当前,经仪器响应失真校正后,加速度计有效观测频带通常为0至1倍自振频率,这限制了强震仪应用领域的延拓。有鉴于此,本文提出一个基于精确权函数的仪器响应失真校正方法并给出一个验证算例。分析表明:较之现有方法,新方法兼有高精度和高效率的优点,并可以将力平衡式加速度计的有效观测频带至少延拓3倍,对于拓展强震仪的应用领域具有重要意义。