莺歌海盆地中央泥底辟带气田水地球化学特征及其油气地质意义

以莺歌海盆地东方区和乐东区气田水样品水化学常规分析为切入点,利用气田水矿化度、水型、钠氯系数(变质系数)、脱硫系数,氯镁系数等参数,深入分析了两区气田水地球化学特征及水化学组合参数特征,并判识对比了两区气藏封闭程度及其保存条件。在此基础上,结合莺歌海盆地天然气成藏地质条件,重点剖析了两区气田水分布规律及成因控制因素,探讨了两区气田水与天然气运聚成藏之间的成因联系。强调指出,两区气田水具有相似的形成演化特征,天然气保存条件好,但对比两区气田水的水化学组合参数,乐东区天然气保存条件稍差于东方区;东方区气田水以NaHCO3水型占绝对优势,其分布规律与断裂系统存在密切联系。该区水文地质开启程度差,气藏盖层封闭性好,有利于天然气富集成藏。乐东区气田水类型多样,成因复杂,天然气保存条件较好但相对东方区稍差。两区气田水具分区分块分布规律,莺歌海盆地泥底辟及其伴生热流体活动对气田水成因及分布规律与天然气运聚成藏等均具有重要控制作用和影响。     

中国煤层气资源控制程度及可靠性分析

准确认识深部条件下气体和水分的赋存状态、相对含量及分布特征,对煤层气高效勘探开发具有重要指导意义。基于理论模型、分子模拟和气水演变分析,明确了煤层中气、水的赋存状态,揭示了气、水动态运聚界限和动态演化过程。考虑煤−水界面作用、水的可动性及赋存状态,煤中水可分为可动水(重力水和毛细水)、束缚水(吸附水、沸石水、结晶水和层间水)、结构水,其中毛细水、重力水和吸附水由孔隙主导,沸石水、结构水、结晶水和层间水由矿物主导。分子模拟结果显示,水分子在0.7 nm孔隙中可以饱和充填,吸附和解吸路径一致,在更大孔隙中出现弱吸附层和自由态。水分子吸附过程表现为单分子含氧基团吸附、单层强吸附、多层弱吸附、水团簇形成和充填孔隙等阶段。甲烷分子在1.5 nm孔隙可存在3层稳定充填吸附,在较大孔隙中(>1.5 nm)即以单层吸附和游离态共存,游离态在介孔及更大孔隙中普遍存在。结合上述吸附−游离气存在界限,改进了游离气和吸附气理论计算公式,为含气量计算提供新思路。深部热成因煤层气是煤大规模生排烃之后的残余气,在排烃过程中发生气驱水和水分蒸发扩散,残余水分为束缚水和结构水,后期无法改变。假定静水压力20 MPa,在0、5、10、15和20 MPa储层压力下,外来水分可入侵最大孔径为7、9、13、27 nm和不侵入。受差异保存条件控制,煤成气除了形成超压和欠压等差异含气系统外,还可能在煤系形成多类型含气模式。上述研究明确了煤层气、水微观赋存机制及形成演化模式,对深部煤层气富集特征及高效开发设计具有指导意义。

     

A new theoretical solution of the effect of atmospheric pressure on water level

Based on the partial differential equation governing the effect of atmospheric pressure on water level of confined well, deriving the boundary condition and considering the seepage water between well and aquifer, the author obtained the analytical solution of water level change in time domain under the action of an atmospheric pressure history with the Laplace transform method. This solution is composed of two terms:stable and retarded terms. The stable term is the multiplication of barometric efficiency and simultaneous atmospheric pressure, and it implies the value of water level after infinite time when the atmospheric pressure is a constant from the time in question. The retarded term is the transient process due to the time lag of water exchange between well and aquifer. From the solution, it is obtained that the interference of atmospheric pressure on water level is the integral superimposition of the contribution of all atmospheric pressure changes before the time in question. So that, we further found out the response function of pulsive atmospheric pressure history. Calculation shows: (1) The pulsive response function starts from zero and tends to a steady value, which is proportional to the barometric efficiency, when the time tends to infinity; (2) The retarded time depends on the mechanical property of aquifer and the radius of well. The larger the seepage coefficient, the smaller the radius of well and the thicker the aquifer, then the shorter the retarded time gets. This solution can be used as the theoretical basis for further analysis of the atmospheric effect and practical correcting method in the future.     

Dynamics of the eco-environmental quality in response to land use changes in rapidly urbanizing areas: A case study of Wuhan,China from 2000 to 2018

Journal of Geographical Sciences - The dramatic land use changes that occur in rapidly urbanized areas are important inducement to changes in the eco-environmental quality. Investigating urban land...     

Late Quaternary paleoenvironments of an ephemeral wetland in North Dakota,USA: relative interactions of ground-water hydrology and climate change

This study of fossils (pollen, plant macrofossils, stomata and fish) and sediments (lithostratigraphy and geochemistry) from the Wendel site in North Dakota, USA, emphasizes the importance of considering ground-water hydrology when deciphering paleoclimate signals from lakes in postglacial landscapes. The Wendel site was a paleolake from about 11,500 ¹⁴C yr BP to 11,100 ¹⁴C yr BP. Afterwards, the lake-level lowered until it became a prairie marsh by 9,300 ¹⁴C yr BP and finally, at 8,500 ¹⁴C yr BP, an ephemeral wetland as it is today. Meanwhile, the vegetation changed from a white spruce parkland (11,500 to 10,500 ¹⁴C yr BP) to deciduous parkland, followed by grassland at 9,300 ¹⁴C yr BP. The pattern and timing of these aquatic and terrestrial changes are similar to coeval kettle lake records from adjacent uplands, providing a regional aridity signal. However, two local sources of ground water were identified from the fossil and geochemical data, which mediated atmospheric inputs to the Wendel basin. First, the paleolake received water from the melting of stagnant ice buried under local till for about 900 years after glacier recession. Later, Holocene droughts probably caused the lower-elevation Wendel site to capture the ground water of up-gradient lakes.     

耐久性设计下水土腐蚀性评价体系的一种解决方案

水土腐蚀性评价标准与混凝土结构耐久性设计的防护标准是相互作用,相互影响的。本文通过2个地下水实例,比较了桩基础和地下室底板在不同规范体系下水土腐蚀性评价标准和防护标准的差异。腐蚀环境越严重,混凝土结构耐久性设计差异越大,因此,有必要统一水土腐蚀性评价标准和混凝土结构耐久性设计的防护标准。针对SO42-和CL-腐蚀性评价差异较大的情况,本文给出了干湿交替作用及其强度的定义,提出了一种统一水土腐蚀性评价指标及其分级的建议方案。干湿交替作用是指在固体表面能够形成液相水与气相水交替转换或持续转换的一种现象,干湿交替作用强度定义为固体表面液态水的相对蒸发速率和固体表层饱和度的乘积。     

利用岩石质量指标和岩体块度指数进行岩体质量评价研究——以高放废物地质处置库预选场址甘肃北山1号钻孔为例

岩体质量的评价对于各类大型建筑物特别是地下工程建筑物的安全性具有十分重要的作用。文章基于岩石质量指标（RQD）和岩体块度指数（RBI）的理论，通过对甘肃北山1号钻孔的岩心实测资料证明，岩体块度指数在一定程度上能反映岩体的完整性与相应力学性质的变化特点，同时给出钻孔附近岩体质量分类，进而与岩石质量指标所获得的钻孔附近岩体质量评价分级进行对比。对比结果表明：岩体块度指数在岩石质量评价中能更准确地反映其优越性，具有更为显著的工程意义。     

桂海碑林摩崖石刻水害成因分析及防治对策

桂海碑林摩崖石刻景区为国家第五批公布的全国重点文物保护单位,其现存的石刻具有极高的史料价值和书法艺术欣赏价值。由于长期受到地质营力的作用,石刻出现了不同程度的水患病害,严重威胁着文物的长期保存。本文通过现场调查将桂海碑林灰岩质摩崖石刻的水患病害归纳为渗（滴）水病害、坡面雨水冲刷病害和凝结水病害三种类型,并分析了裂隙水、雨水和凝结水诱发石刻损坏的成因机制。为查明裂隙水的运移特征,采用瑞雷波探测技术识别了石刻岩体内部潜在的渗流通道,并基于瑞雷波相速度VR分级对其进行了渗透性分级。基于探测结果结合石刻区的地貌特征,提出了在崖顶区采用土工合成材料黏土衬垫（GCL）防渗铺盖和坡顶截水,在石刻区采用裂隙注浆和表面防水封护的综合治理对策。     

渭河流域地表水可利用量分析计算

地表水可利用量是流域和区域水资源规划的重要指标.本文应用断面过流量减去河道内生态需用水量与河道外难控制利用弃水量,并扣除二者间重复计算量的算法,利用华县、状头两个水文站断面实测和统计数据,分析计算渭河多年平均地表水可利用量为54.91亿～66.33亿m~3/a.     

关中盆地地下热水接受补给时温度及热储层温度的估算

通过对关中盆地地热井中地下热水的同位素和水化学成分分析,结合研究区的地热地质和水文地质条件,进行了地下热水补给时的温度研究,结果表明,关中盆地地下热水接受补给时的温度以西安地区最低,咸阳次之。同时应用Na-K-Mg三角图和水化学平衡温度理论的方法,估算在平衡条件下关中盆地最大热储温度为118℃。热储温度计算结果表明,关中盆地腹部应为中低温热储层。