塔里木盆地和田河气田碳酸盐岩储层的多期次多来源油气聚集特征

高成熟度演化地区的海相碳酸盐岩储层易受到油气演化的影响 ,油气的聚集在储层中都留下了踪迹 ,既有对储层储集性能的改善有利的一面 ,也有对储层形成伤害的一面。对和田河气田的碳酸盐岩储层薄片观察、凝析油气的地球化学分析和储层沥青分析表明 ,主要有 3期油气运移 ,分别为 :晚加里东期—早海西期、晚海西期和喜山期。前两期都是寒武系来源的油气 ,均被生物降解或散失 ,喜山期是天然气的关键聚集时期。第一期以油相运聚的油气被降解 ,形成的沥青对储层造成了伤害 ,第二期以气相运移的油气多散失 ,仅在储层中留下凝析油 ,第三期油相运移的石炭系来源的油受到后期转移上来的寒武系干气的气侵 ,产生沥青质沉淀 ,使得寒武系凝析油被封堵 ,储层产出的凝析油的地球化学特征更接近石炭系源岩。     

鸳鸯沟洼陷西斜坡成岩作用定量表征及有利区带预测

储层实测孔隙度、普通薄片、铸体薄片和扫描电镜的资料表明,辽河坳陷鸳鸯沟洼陷西斜坡新生界储层在纵向上发育三个次生孔隙带。从而在一个普遍低孔渗背景下,形成了孔隙度相对较高的优质储层。优质储层的形成和分布主要受沉积微相和成岩作用的双重影响与控制。它们形成于辫状分流河道、河口坝+席状砂沉积微相,目前处于早成岩阶段B期—中成岩阶段A1亚期,发育溶蚀成岩相。该文通过成岩作用定量表征方法,预测了鸳鸯沟洼陷西斜坡成岩阶段和成岩相的横向展布。通过成岩相图和沉积微相图的叠合,预测了沙三中上亚段优质储层的分布。预测结果表明,优质储层主要发育于斜坡区的中部。     

人工回灌过程中地下水微生物群落变化

人工回灌过程中,回灌水的注入使目的含水层地下水环境发生变化,微生物条件也会随之改变,从而影响地下水环境质量及水文地球化学作用。以上海市某人工回灌试验场为例,在分析人工回灌过程中水化学演化特点的基础上,应用DGGE技术对场地回灌过程中地下水中的微生物群落结构变化进行研究,为评价人工回灌对地下水水质安全的影响提供科学的理论依据。结果表明:人工回灌作用使目的含水层地下水中的Eh值及DO质量浓度升高,分别由64.0 mV、1.12 mg/L升至534.4 mV、1.44 mg/L;同一位置处微生物群落结构与原始地下水状态的相似性随时间降低;同一时刻距离回灌井越远的监测井的微生物群落结构越接近于原始地下水状态。随着回灌的进行,目的含水层地下水中优势菌属(种)共有7种,其中Rubrivivax gelatinosus和Candidatus Accumulibacter phosphatis clade IIA str.的反硝化能力以及Rhodoferax ferrireducens对Fe³⁺的还原能力,对地下水水化学组分产生影响。     

兰州盆地44～15Ma地层的有机碳同位素记录

沉积物中有机碳同位素组成是重建古环境变化的有效指标,但陆地长序列的有机碳同位素记录目前较为罕见.本文选取兰州盆地已具古地磁测年的永登剖面(厚度为330～1310m部分,年代介于44～ 15Ma)进行了有机碳同位素分析,结果表明44Ma开始其值先逐渐偏重后变轻(平均-24.6‰),至33.2Ma突然变重后维持相对稳定的高值(平均-23.7‰),再至25.5Ma后又变轻(-24.4‰),与全球氧同位素从长期演化趋势以及事件上均呈现出较一致的对应关系,即与温度之间存在负相关.这表明兰州盆地中始新世-中中新世期间有机碳同位素变化可能受控于全球温度变化,温度的改变可能影响了陆源C3植物与湖泊内生沉水和挺水植物对有机质的相对贡献比例,确切的机制理解有待其他指标的辅助研究.     

柴达木盆地西部英东地区油气成藏过程

柴达木盆地西部英东地区多期构造运动导致油气分布复杂,勘探难度大.采用油气地球化学、流体包裹体、定量荧光以及傅里叶红外光谱等方法系统分析英东地区油气成藏演化过程.研究表明:(1)英东地区新近系储层发育黄色和蓝色荧光两类油包裹体和天然气包裹体,黄色荧光和蓝色荧光油气包裹体对应两期油气充注时间分别为12 Ma和5 Ma.(2)现今油藏原油具有同源-低熟的特点,黄色荧光油包裹体成熟度较低与现今油藏原油特征相似, 是现今油藏的主要贡献者.(3)蓝色荧光油包裹体的成熟度较高,蓝色荧光油包裹体和气烃包裹体是早期低熟原油沿后期构造产生的断层疏导体系向上调整运移至浅层分馏和脱气的产物.通过以上分析明确了英东油藏经历了下油砂组(N₂1)沉积末期(12 Ma)的低熟原油充注和上油砂组(N₂2)沉积末期(5 Ma)至今油气调整与改造的成藏过程, 与喜山期主要构造活动期有很好的对应关系,反映构造活动对油气成藏具有重要控制作用.      

A method predicting the earthquake-induced landslide risk by back analyses of past landslides and its application in the region of the Wenchuan 12/5/2008 earthquake

The work considers critical slopes located at regions with high danger and proposes a method which approximately predicts the risk of earthquake-induced excessive movement of these slopes, in the case where relevant soil strength data along their slip surface do not exist. The method utilizes (1) simplified constitutive equations predicting soil response along slip surfaces and (2) a multi-block sliding system model, both recently proposed. It involves the following steps: (a) collect relevant topographic information and laboratory test results of past landslides at the region of interest, (b) (i) analyze the relevant laboratory tests to estimate the soil constitutive parameters and (ii) estimate the mobilized residual soil strength by back analysis of relevant past landslides, (c) select constitutive model parameters for future applications at the region based on step (b) and validate them based on analysis of the triggering of the past landslides and (d) apply the selected constitutive model parameters in critical slopes in the region under consideration to predict not only whether triggering occurs, but also the post-triggering slide deformation. The paper, after describing in detail the proposed method, applies it at the Wenchuan region, where the 12th May 2008 earthquake triggered many landslides. During the application, four ring shear test results and twelve landslides of the 12th May 2008 earthquake were considered. The application was successful and the following were observed: (i) in the back analyses, the multi-block model predicted reasonably well the final configuration of all slides, (ii) apart from two significantly larger back-estimated values of the residual soil strength, small scatter existed in the other back-estimated values and (iii) the selected model parameters were duly validated under step (c). Furthermore, as the back-estimated friction angle of most landslides was less than 18°, and the materials along the slip surface have a Liquid Limit value less than 25 %, it is inferred that some, or all of the slip surface during these slides, was sheared in an undrained manner.     

青海南山沟后岩浆杂岩体锆石U-Pb年代学、岩石成因及其地质意义

青海南山构造带是衔接宗务隆构造带、南祁连构造带和西秦岭造山带的重要结合带。沟后岩浆杂岩体位于青海南山构造带东段,主要由辉长岩、辉长闪长岩、石英闪长岩、花岗闪长岩组成。本文对沟后岩浆杂岩体进行了详细的岩石学、岩石地球化学和LA-ICP-MS锆石U-Pb同位素年代学研究。结果表明,辉长岩、辉长闪长岩、石英闪长岩、花岗闪长岩及暗色微粒包体的结晶年龄分别为248.8±2.6 Ma、243.2±2.1 Ma、243.1±0.9 Ma、244.0±2.1 Ma和249±3 Ma。辉长岩富铁、镁,贫碱;辉长闪长岩高铝、富钙和钠,二者均为钙碱性岩类。石英闪长岩和花岗闪长岩为准铝-弱过铝质高钾钙碱性岩,暗色微粒包体属钙碱性-碱性岩系列。不同岩石类型均表现为富集大离子亲石元素(Cs、Rb、K)和Pb,亏损高场强元素(Nb、Ta、Ti)和P、Ba负异常;稀土元素配分曲线均具有轻重稀土分异的右倾特征,具弱-中等负Eu异常。岩相学和岩石地球化学特征表明沟后岩浆杂岩体具壳幔岩浆混合特征,暗示其可能形成于由俯冲流体交代地幔楔部分熔融的幔源岩浆底侵作用下的构造环境。辉长岩为幔源岩浆经分离结晶的产物,辉长闪长岩为幔源岩浆经分异演化并混染少量壳源岩浆的产物;中基性岩浆与壳源中酸性岩浆发生混合并经历一定的分异演化过程形成了石英闪长岩和花岗闪长岩。结合区域地质资料分析认为,沟后岩浆杂岩体可能代表了研究区早三叠世晚期-中三叠世早期宗务隆洋向南消减作用相关的构造岩浆事件。     

Identifying sediment sources from the inter-gully area and gully area in a small watershed in the Loess Hilly Region of China

Understanding the sediment source is very significant for erosion control in small watersheds. On the Loess Plateau of China, over 110 thousands of check dams were constructed in the past 60 years, which played an important role in controlling soil loss and also kept much information of erosion and sediment yield in the past. The objective of this investigation is to identify the sediment source by the ¹³⁷Cs tracing method in a small watershed in the Loess Hilly Region of China. Fifty-five sampling sites were selected from the watershed (44 from the inter-gully area, 7 from the gully sides and 4 from the reference sites), and a total of 114 soil samples were collected from three sediment profile cores at the Sidizui watershed check dam constructed in 1959. Based on the erosion rate from the inter-gully area by the ¹³⁷Cs models, and the total erosion amount deposited in the check dam since 1963, the relative contributions of sediment from the inter-gully area and gully area were estimated during 1963–2013. By comparing the difference of ¹³⁷Cs activities of surface soils from the check dam (deposited in the 2011–2013 flood events), the inter-gully and gully areas, the relative contributions of sediment derived from the two source areas to the flood sediment during recent years (2011–2013) were estimated by a simple mixing model. Results showed that the erosion rate from the inter-gully area was about 3054 t/km² a during 1963–2013, and the relative contributions of sediment from the inter-gully area and gully area were estimated to be 27 and 73%, respectively. The sediment from the inter-gully area was about 20% of the total sediment yield amount to the 2011–2013 floods, and from the gully area it was about 80%. The relative contribution of sediment from the inter-gully or gully area was not a fixed value in the watershed. Both of the inter-gully erosion and gully erosion should be simultaneously controlled, and more erosion control measures on the gully area should be taken in the subsequent watershed management in order to reduce the erosion amount in this region.     

川中低孔渗砂岩成岩相定量评价与快速预测——以遂宁—蓬溪须二段为例

四川盆地中部上三叠统须家河须组须二段砂岩储层是中国低渗致密砂岩的突出代表,成岩作用对于砂岩致密化具有重要影响。借助铸体薄片、阴极发光、电子探针、扫描电镜等实验分析手段,分析不同成岩作用类型及特征,以控制孔隙演化的主要或特征的成岩作用划分出6种成岩相;引入视压实率、视胶结率、视微孔率、成岩系数结合孔渗参数,定量评价不同成岩作用强度,区分不同成岩相类型;探索地应用稳健回归方法建立孔渗-成岩系数解释模型;利用成岩系数解释模型解释未取心井参数,绘制成岩系数等值线平面图,预测有利成岩相区域分布。绘制储层(孔隙度6%)成岩系数等值线平面图,预测有利成岩相-有利储层发育区,实现了成岩作用、成岩相定量评价,成岩相的快速预测,并为有利储层发育区的筛选提供了依据,对于致密砂岩气藏勘探开发具有指导性意义。     

Identification of a locking segment in a high-locality landslide in Shidaguan,Southwest China

Natural Hazards - Identification of a locking segment is crucial to assess the potential runout risk and the overall stability of a high-locality landslide. However, it is difficult to...