坡折带控制下的砂质碎屑流对油气勘探的意义——以四川盆地上三叠统须家河组为例

坡折带近年来日益受到重视,它明显控制了上覆地层分布、岩性岩相变化和油气藏的分布。通过层序地层法恢复古地貌,在川中-川西过渡带识别大型地貌坡折带,川西地区晚三叠世接受其西部和东部两个方向的物源供给。在大量岩心观察、地震资料和测井资料研究基础上,认为在坡折带控制下,龙泉山断裂带以西须二、须四段发育砂质碎屑流重力流沉积,分析其基本特征和储集性能,最后指出砂质碎屑流储层物性总体优于川西地区南部其它类型砂体,是新型的勘探对象,具有一定的勘探潜力。     

基于Biot-Gassmann 方程的流体替换技术在番禺天然气区PY 气田的应用

珠江口盆地番禺天然气区PY 气田位于坡折带上,特殊的沉积环境导致该气田已钻探的各井 T50 储层泊松比关系异常,含油气性特征非常复杂。为更好的判断储层的含油气性,利用Biot-Gassmann 方程对坡折带储层的流体性质进行了替换,考查不同流体性质下储层的含油气响应特征。研究结果表明: Biot-Gassmann 方程能有效的用于坡折带储层的流体替换研究; 坡折带T50 储层含水和含气时的AVO 响应特征相近,但两者响应的幅值不同,含水砂岩的幅值更小。     

辽河滩海地区古近系层序地层特征及控砂、控藏作用

运用层序地层学原理,对辽河研究区滩海地区古近系主要构造沉积旋回和关键层序界面特征进行分析,划分出4个二级层序和11个三级层序。结果显示:古近系层序的发育特征主要受构造活动的性质、强度及沉积旋回控制,二级层序界面为构造格局、沉积环境转换界面,控制沉积体系和相类型;三级层序界面为层序叠加样式或沉积环境转换面,控制层序内的体系域特征和演化。平面上,砂体分布受古地貌、坡折带性质和规模控制;纵向上,砂体发育受不同级次的沉积旋回或体系域控制。储盖组合分析,表明,二级层序和最大区域湖泛面控制成藏组合,三级层序及体系域控制油气层纵向分布。     

珠江口盆地陆架坡折带海底滑坡及其影响因素

为了解海底滑坡在陆架坡折演化过程中所起的作用并分析影响海底滑坡发育的因素,以最新采集的二维和三维地震资料为基础,综合运用了地貌分析和地震解释技术,通过对滑坡的地貌形态特征及地震响应特征进行详细刻画,在珠江口盆地陆架坡折带新近纪地层中识别出多处海底滑坡,明确了其分布范围并建立了滑坡发育的地质模式。分析认为,珠江口盆地相对海平面变化和流体活动的综合作用是导致研究区海底不稳定的主要因素。海底滑坡发源于海底峡谷的朔源侵蚀,向上陆坡扩展并终止于陆架坡折带。     

高温胁迫下皱纹盘鲍不同养殖群体心率变化比较

高温是海水贝类度夏死亡的环境诱因之一。本研究应用一种非损伤性的心率检测方法,检测两个皱纹盘鲍养殖群体在高温胁迫条件下心率等生理指标的变化,尝试以心率变化指标比较这两个群体高温耐受能力。由于高温胁迫下皱纹盘鲍的心率随温度变化的关系符合阿伦尼乌斯(Arrhenius)公式,且心率随温度上升呈先上升后下降趋势,该研究通过计算两者直线拟合拐点即阿伦尼乌斯拐点温度(ABT,Arrhenius break temperatures)指标,用以指示皱纹盘鲍温度耐受程度。以此法对皱纹盘鲍两个群体(高温耐性,对照)各17个个体进行了测定分析,结果表明:两个群体间的ABT存在显著差异,高温耐性组的皱纹盘鲍的ABT显著高于对照组(P0.05);个体ABT指标的高低与测定个体的壳高呈正相关(P0.05)。本研究首次将探讨了高温胁迫下皱纹盘鲍心率变化规律,并以ABT为指标分析比较了两个皱纹盘鲍养殖群体间高温耐受能力,结果对研究皱纹盘鲍和其它贝类温度胁迫下生理响应及抗逆选育具一定借鉴意义。     

Mesozoic exhumation history of the Grenvillian Oaxacan Complex,southern Mexico

We present the first fission‐track results from the Grenvillian Oaxacan Complex, southern Mexico. Time–temperature modelling of the data indicates that two significant Mesozoic cooling episodes are recorded in the Oaxacan Complex and these are interpreted as resulting from exhumation. The older cooling event took place from the Late Triassic to Middle Jurassic and is possible linked to the break‐up of Pangea (including the initial opening of the Gulf of Mexico during the Jurassic). The younger exhumation period in the Early Cretaceous is contemporaneous with the final stages of rifting of the Gulf of Mexico. Key stratigraphic records also provide independent evidence for these exhumation episodes. In our view, both Mesozoic rapid exhumation events were controlled by the activity of the Caltepec Fault Zone and the Oaxaca Fault. Our data suggest that both these large fault systems have remained active since, at least, the Late Triassic.     

Assessment of annual high‐water events for the Mackenzie River basin,Canada

River ice break‐up is known to have important morphological, ecological and socio‐economic effects on cold‐regions river environments. One of the most persistent effects of the spring break‐up period is the occurrence of high‐water events. A return‐period assessment of maximum annual nominal water depths occurring during the spring break‐up and open‐water season at 28 Water Survey of Canada hydrometric sites over the 1913–2002 time period in the Mackenzie River basin is presented. For the return periods assessed, 13 (14) stations are dominated by peak events occurring during the spring break‐up (open‐water) season. One location is determined to have a mixed signal. A regime classification is proposed to separate ice‐ and open‐water dominated systems. As part of the regime classification procedure, specific characteristics of return‐period patterns including alignment, and difference between the 2 and 10‐year events are used to identify regime types. A dimensionless stage‐discharge plot allows for a contrast of the relative magnitudes of flows required to generate maximum nominal water‐depth events in the different regimes. At sites where discharge during the spring break‐up is approximately one‐quarter or greater than the magnitude of the peak annual discharge, nominal water depths can be expected to exceed those occurring during the peak annual discharge event. Several physical factors (location, basin area, stream order, gradient, river orientation, and climate) are considered to explain the differing regimes and discussed relative to the major sub‐regions of the MRB. Copyright © 2008 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.     

A laboratory investigation of bed-load transport of gravel sediments under dam break flow

Dam break flows and resulting river bed erosion can have disastrous impacts on human safety,infrastructure,and environmental quality.However,there is a lack of research on the mobility of non-uniform sediment mixtures resulting from dam break flows and how these differ from uniform sized sediment.In this paper,laboratory flume experiments revealed that coarse and fine fractions in non-uniform sediment had a higher and a lower bed-load parameter,respectively,than uniform sediments of the same size.Thus,the finer fractions were more stable and the coarser fractions were more erodible in a nonuniform bed compared to a uniform-grained bed.These differences can be explained by the hiding and protrusion of these fractions,respectively.By investigating changes in mobility of the mixed-size fractions with reservoir water levels,the results revealed that at low water levels,when the coarser fractions were only just mobile,the bed-load parameter of the finer fractions was higher than the coarser fractions.The opposite was observed at a higher water level,when a significant proportion of the coarsest fractions was mobilized.The higher protrusion of these grains had an important effect on their mobility relative to the finer grains.The transported sediment on these mixed-sized beds was coarser than the initial bed sediment,and became coarser with an increase in reservoir water level.     

松辽盆地北部他拉哈-齐家地区姚一段沉积与成藏特征再认识

综合20口井岩心和496口井测井、录井及分析化验资料,对松辽盆地他拉哈-齐家地区姚一段葡萄花油层进行高分辨率层序地层研究,提出葡萄花油层北、西部为同沉积构造抬升控制的底部缺失的层序地层新格架。研究区最有利相带砂体为窄而细的末梢河道砂、薄层河口坝及席状砂体,而研究区北半部大量宽泛的厚层优质河道砂却不含油,为大面积含水区。研究总结发现,砂体发育与岩性油气藏分布均受控于一挠曲坡折带,坡折带以内为低水位体系域沉积质量中心,砂岩厚薄相间,可形成地层超覆圈闭;坡折带之下为3个层序低水位和水进体系域三角洲前缘砂体叠合区,发育的砂岩较薄且连通性差,是多层位岩性圈闭和上倾尖灭型圈闭发育区;坡折带之上以水进体系域平原相及前缘相的大量厚层河道砂体为主,但因连通性好,油气易散失,不易形成岩性圈闭,而成为大范围的含水区。坡折带"控层""控相""控砂""控藏"的理论在本研究区又一次得到极好的应用与验证。     

Shallow water SPH for flooding with dynamic particle coalescing and splitting

In this paper an adaptive algorithm for Smoothed Particle Hydrodynamics (SPH) for the Shallow Water Equations (SWEs) is presented. The area of a particle is inversely proportional to depth giving poor resolution in small depths without particle refinement. This is a particular limitation for flooding problems of interest here. Higher resolution is created by splitting the particles, while particle coalescing (or merging) improves efficiency by reducing the number of the particles when acceptable. The new particle coalescing procedure merges two particles together if their area becomes less than a predefined threshold value. Both particle splitting and coalescing procedures conserve mass and momentum and the smoothing length of new particles is calculated by minimizing the density error of the SPH summation. The new dynamic particle refinement procedure is assessed by testing the numerical scheme against analytical, experimental and benchmark test cases. The analytical cases show that with particle splitting and coalescing typical convergence rates remain faster than linear. For the practical test case, in comparison to using particle splitting alone, the particle coalescing procedure leads to a significant reduction of computational time, by a factor of 15. This makes the computational time of the same order as mesh-based methods with the advantage of not having to specify a mesh over a flood domain of unknown extent a priori.