白云岩与砂岩致密储集体质量的差异性

白云岩与砂岩致密储集体质量参数为随机分布的连续谱系，孔隙结构、物理参数复杂多变，表征难度较大。基于铸体薄片、压汞、核磁共振、孔隙度和渗透率等测试技术，结合大量天然气勘探开发实际资料，采用统计分析对比方法，重点讨论了储层质量宏观与微观参数特征。结果表明，白云岩与砂岩致密储集体质量参数具有正态分布特征，是一种金字塔数据结构，常规储层比例一般为15%~20%，是砂岩或白云岩致密储层的“甜点”；致密砂岩储层微观孔隙发育，孔、喉连通性较好，分布比较均匀，储层孔、渗关系较好，表现为相对高孔和低渗；白云岩致密储层质量尽管具有孔、喉连通性差和孔、渗关系较差的不利因素，但也具有相对高渗、低束缚水饱和度、低排驱压力及裂缝网络发育等有利因素，天然气渗流能力较好，勘探开发潜力较大。我国发育碳酸盐岩沉积，应加强致密白云岩气藏成藏条件研究与勘探。     

Dam effects on bedload transport on the upper Santa Ana River,California, and implications for native fish habitat

Dams disrupt the flow of water and sediment and thus have the potential to affect the downstream geomorphic characteristics of a river. Though there are some well‐known and common geomorphic responses to dams, such as bed armouring, the response downstream from any particular dam is dependent on local conditions. Herein, we investigate the response of the upper Santa Ana River in southern California, USA, to the construction of a large dam at the transition from mountains to valley, using calculations of bedload transport capacity on the mainstem below the dam and for major tributaries. Approximate sediment budgets were constructed for downstream reaches to estimate deposition and erosion rates for sand, gravel, and cobble particle sizes. Our results indicate that the classical response of bed armouring and erosion is likely limited to a short reach immediately below the dam. Farther downstream, though transport capacity is reduced by flow regulation by the dam, the channel reaches are likely to remain depositional but with reduced deposition rates. Persistent deposition, as opposed to erosion, is the result of the replenishment of flow and sediment supply by large downstream tributaries. In addition, the calculations indicate that the composition of the bed is unlikely to change substantially in downstream reaches. A Monte Carlo approach was employed to estimate the uncertainty in the sediment budget predictions. The impacts of the dam on the geomorphic character of the river downstream could have implications for native fish that rely on coarse substrate that supports their food base.     

基于振动实测的非均质地层钻头失效分析与对策

四川盆地作为国内页岩气开发的重点区域,通过近几年的不断攻关和实践,机械钻速得到了提高,但由于受地层复杂、可钻性差、非均质性强等地质因素的影响,导致井下钻柱系统不良振动剧烈,容易出现钻头损坏严重、钻速较低等问题,严重影响了钻井时效。为了解决上述难题,以该盆地涪陵工区上二叠统龙潭组—中二叠统茅口组为例,采用井下振动高频测量工具的实测手段,测量了钻头—钻柱系统的动态振动加速度参数,结合地层的岩性和矿物组分分析,研究钻头失效原因与对策,并开展了现场试验。研究结果表明:①在非均质地层中钻进的钻头—钻柱系统产生了大于40 m/s~2的高幅值瞬时冲击振动,高幅值的瞬时冲击是导致钻头先期失效的主要原因;②提出了抑制高幅值的瞬时冲击振动采用"减振+增压"工具组合和避免井下工具共振的钻井参数;③采用钻井新参数的试验井比邻井的高幅值瞬时振动降低了17%,单只钻头进尺增加24%,钻头工作环境得到了较大的改善,钻头使用数量减少。结论认为,该研究成果能够有效地改善钻头—钻柱系统的振动状态,有利于达成延长钻头使用寿命的目标。     

塔里木盆地中秋1凝析气藏成藏条件及演化过程

2018年12月,塔里木盆地秋里塔格构造带天然气勘探取得重大突破,中秋1井在下白垩统巴什基奇克组测试获高产工业气流,发现了该构造带迄今为止最大的整装凝析气藏。为了给该构造带下一步油气勘探部署提供依据,在充分利用前人研究成果的基础上,基于岩心、薄片、测井及地球化学分析资料,明确了中秋1大型凝析气藏的油气藏特征和气藏类型,分析了该气藏天然气成藏条件并推演其演化过程。研究结果表明:①中秋1大型气藏属于低含凝析油凝析气藏,天然气为煤成气,主要来自区内侏罗系腐殖型煤系烃源岩;②该构造带能够形成大型油气藏的有利地质条件是三叠系和侏罗系发育的两套巨厚高演化烃源岩、白垩系发育的大型辫状河三角洲规模有效砂岩储层、喜马拉雅晚期以来的构造活动形成的大规模楔状叠瓦构造圈闭、古近系和新近系巨厚膏盐岩形成的优越保存条件,以及油气生成与圈闭形成的良好时空匹配;③该气藏具有先油后气、晚期快速气侵聚集成藏的成藏模式,总体上是一个"早期聚油、晚期气侵、改造调整、快速成藏"的成藏过程。结论认为,该构造带油气成藏条件优越,具有广阔的油气勘探前景。     

Environmental factors controlling phytoplankton dynamics in a large floodplain river with emphasis on cyanobacteria

Harmful algal blooms are occurring in large river ecosystems and at the mouth of large rivers with increasing frequency. In lentic systems, the chemical and physical conditions that promote harmful algal blooms are somewhat predictable but tracking prevalence and conditions that promote harmful algal blooms in lotic systems is much more difficult. We captured two of the most extreme discharge years within the last 20 years occurring in the Upper Mississippi River, allowing a natural experiment that evaluated how major shifts in discharge drive environmental variation and associated shifts in phytoplankton. Statistical models describing significant environmental covariates for phytoplankton assemblages and specific taxa were developed and used to identify management‐relevant numeric breakpoints at which environmental variables may promote the growth of specific phytoplankton and/or cyanobacteria. Our analyses supported that potentially toxin‐producing cyanobacteria dominate under high phosphorus concentration, low nitrogen concentration, low nitrogen‐to‐phosphorus ratio, low turbulence, low flushing, adequate light and warm temperatures. Cyanobacteria dominated in 2009 when low discharge and low flushing likely led to optimal growth environments for Dolichospermum, Aphanizomenon and Microcystis. Rarely will a single factor lead to the dominance, but multiple positive factors working in concert can lead to cyanobacteria proliferation in large rivers. Certain isolated backwaters with high phosphorus, low nitrogen, warm water temperatures and low potential for flushing could benefit from increased connection to channel inputs to reduce cyanobacterial dominance. Numerous examples of this type of habitat currently exist in the Upper Mississippi River and could benefit from reconnection to channel habitats.     

城市大型给水工程系统迁建设计

在环保督察背景下,城市饮用水水源保护问题凸显。以铜陵为例,介绍城市大型取水口、对应水厂系统迁建设计案例。铜陵市三水厂横港取水口水源保护区内存在多座码头,结合铜陵市长江岸线规划、现状供水布局及存在问题,将横港取水口、三水厂整体迁建至下游新民取水口附近,设计规模为30万m^3/d,同步建设配套给水管道,将原三水厂改造为加压泵站,工程建成后逐步关停现状一、二水厂,形成更加科学合理的供水系统。     

A comparison of Zayandehrood River water values for agriculture and the environment

River water management is challenging not only since they are open systems with changing physical structures, but also because the water values are mostly unknown over varied sectors. If policymakers grasp water values, water management will be more efficient. This research intends to examine the values of water in agriculture, which receives the most substantial portion of water resources, with the values of water in the environment in Isfahan located in the Zayandehrood River basin of Iran. The consequences of contingent valuation and production function methods revealed that per cubic metre value of water is 13 times higher in the environment than agriculture. The government should reconsider the higher value of the environment despite it is a non‐market value. The contingent valuation model additionally proved that women exhibited 21% more willingness to pay than men in order to protect the environment; however, they are paid less by 36%.     

江汉盆地潜江凹陷古近系潜江组白云岩成因

潜江凹陷位于江汉盆地，其古近系潜江组以含有由富有机质白云岩和蒸发岩组成的193个韵律层为特征。然而，潜江凹陷古近系潜江组白云石的成因一直存在争议，限制了进一步对非常规油气的勘探工作。根据盐间层岩相与矿物特征研究潜江组盐间层富白云石岩相的沉积成因。根据沉积特征观测（岩心和薄片）和矿物组分数据，可识别出3种主要的岩相结合：薄层-纹层状泥晶白云岩、纹层状含云泥晶灰岩和夹钙芒硝层状泥晶白云岩。研究发现前两种岩相组合纹层特征明显，可见有机质纹层与无机纹层交互现象，说明形成于水体较深的还原环境。白云石与方解石晶体含有有机质降解孔，且白云石与黄铁矿和有机质薄膜共生，说明其成因与微生物诱导活动有关。浮游微生物和底栖藻分别控制了方解石和白云石的沉淀。这些岩相组合含有较高的有机质含量。最后一种岩相组合具有较高的蒸发矿物含量和陆源碎屑物质，说明其形成于相对浅水环境。高盐度和强烈陆源输入不利于有机质的保存。此次研究发现盐湖内白云石的形成受微生物活动和蒸发环境控制，不同的成因对岩相沉积特征和有机质富集产生重要影响。     

克拉苏构造带盐下超深层储层的构造改造作用与油气勘探新发现

塔里木盆地克拉苏构造带油气群下白垩统巴什基奇克组埋深超过6 000 m,储层基质渗透率低,裂缝普遍发育,构造对储层的改造作用明显,但博孜9井的勘探突破反映出不同区带间构造改造作用差异较大、非均质性极强,重新认识构造对储层的改造作用对于预测超深层储层、指导油气勘探生产具有重要的意义。为此,基于钻井取心、构造平衡恢复、裂缝充填物同位素测年、区块应力数值模拟等资料,结合流体包裹体、声发射古应力、铸体薄片等实验分析方法,从定性分析到定量计算、研究了克拉苏构造带油气群超深层储层的构造改造作用及其差异性。研究结果表明:①北部天山造山带及南部古隆起控制了该构造带储层的沉积格局及差异构造变形,形成巴什基奇克组储层"西薄东厚"的分布特征;②博孜区段古应力最小,构造变形主要为正向挤压、逆冲传播,局部井区为斜向压扭;③大北区段主要为斜向压扭,古应力较小,构造变形为逆冲叠置;克深区段古应力最大,构造变形主要为正向挤压、后缘逆冲抬升、前缘滑脱收缩;④差异构造变形使同一构造带不同构造变形样式的构造减孔量呈现出较大的差别,且控制了不同区段造缝期与成岩胶结的叠加影响、中晚期裂缝网络与油气成藏期的配置关系,加剧了储层的非均质性,是区段间产能差异的基础改造因素;⑤现今构造应力的大小及方向影响裂缝有效性,南部为强挤压应力区,背斜相对高部位裂缝走向与现今应力交角较小,裂缝有效性最好;⑥构造成岩环境决定了构造裂缝充填物的类型,北部区块以淡水—半碱水介质成岩环境为主,裂缝充填物类型为方解石,有利于对储层进行酸化压裂改造。     

Assessment of the different sources of uncertainty in a SWAT model of the River Senne (Belgium)

Although rainfall input uncertainties are widely identified as being a key factor in hydrological models, the rainfall uncertainty is typically not included in the parameter identification and model output uncertainty analysis of complex distributed models such as SWAT and in maritime climate zones. This paper presents a methodology to assess the uncertainty of semi-distributed hydrological models by including, in addition to a list of model parameters, additional unknown factors in the calibration algorithm to account for the rainfall uncertainty (using multiplication factors for each separately identified rainfall event) and for the heteroscedastic nature of the errors of the stream flow. We used the Differential Evolution Adaptive Metropolis algorithm (DREAM_(zs)) to infer the parameter posterior distributions and the output uncertainties of a SWAT model of the River Senne (Belgium). Explicitly considering heteroscedasticity and rainfall uncertainty leads to more realistic parameter values, better representation of water balance components and prediction uncertainty intervals.