矿用钻孔超声流量自适应检测技术     

代晨昱  赵朋朋  徐晶 《煤田地质与勘探》2022,50(1):59-65

为了更好地实现煤矿井下瓦斯抽采钻孔端流量监测,针对管路内介质成分复杂、纯净度差、稳定性差等因素对抽采流量参数测量准确性影响的问题,提出以时差法为测量原理,以双阈值比较法为检测方法,设计了一套矿用钻孔超声流量自适应检测系统。通过分析影响双阈值比较法测量准确性的关键问题出发,设计了检测系统的总体方案,并对其中激励信号放大电路、接收信号调理电路及由峰值检波电路与增益控制电路构成的自适应电路几项关键模块进行了详细地介绍,叙述了检测系统运行软件的工作流程。通过工况环境适应能力测试与准确度性能检验,对检测系统的功能与性能进行了检验,检验结果表明,该系统能够适应瓦斯抽采钻孔管路内的工况需求,实现高精度的气体流量测量。   相似文献   

氡(222Rn)在地下水-地表水相互作用中的应用研究进展     

廖福  罗新  谢月清  易立新  李海龙  王广才 《地学前缘》2022,29(3):76-87

地下水-地表水相互作用是水资源管理和地表水生态系统保护中重要的一个环节,氡同位素(²²²Rn)由于其在地下水与地表水中含量差异显著、性质保守、检测难度低,广泛运用于地下水-地表水相互作用的研究当中。本文通过总结分析²²²Rn在不同地表水体(海水、河水、湖水等)中的应用,指出刻画地下水氡浓度的异质性是估算地下水排泄的重点和难点。在估算海底地下水排泄(SGD)时,氡的混合损失项估算不确定、海水氡浓度时空变异性、SGD的多组分特征等可能给估算结果带来较大不确定性;在估算河流地下水排泄时难以确定氡的大气逃逸量;研究人员对氡在示踪地表水补给地下水方面的研究程度相对不足。本文从科学研究和实际生产方面,对²²²Rn的研究应用提出以下潜在方向:(1)降低地下水氡空间变异性对估算地下水排泄量的影响;(2)针对不同水体、不同水文条件,准确刻画氡的大气逃逸量;(3)拓展²²²Rn示踪能够解决的科学问题;(4)将氡质量平衡模型计算与不确定分析相结合,实现软件化。  相似文献   

天津平原区加油站地下水石油烃污染特征及其生物降解机理研究     

刘学娜  李海明  李梦娣  章卫华  肖瀚 《地学前缘》2022,29(3):227-238

加油站地下水中石油烃污染是较为普遍的现象,本文对研究区位于不同水文地质条件的加油站地下水进行取样分析,分析加油站地下水中石油烃的污染特征和地下水化学类型特征,并运用因子分析、相关性分析和多元回归分析揭示加油站地下水中石油烃潜在的生物降解机制。研究结果表明,地下水化学类型主要可划分为Cl-Na型、HCO₃-Na型、HCO₃-Ca型和SO₄-Na型4类。加油站地下水中石油烃的检出率为85.71%,检出浓度为0.020.35 mg/L。因子分析结果表明影响地下水化学组成的因素主要以水-岩相互作用和石油烃的生物降解为主。TPH与地下水化学指标间的相关关系表明:TPH与K⁺、Na⁺、Cl^-、Mn、Mg²⁺、 {\mathrm{SO}}_4^{2-}呈现负相关的关系,与pH值、 {\mathrm{HCO}}_3^{-}、 {\mathrm{NO}}_3^{-}、 {\mathrm{NO}}_2^{-}、Ca²⁺、Fe不存在显著的相关关系。加油站地下水环境中可能存在嗜盐或耐盐微生物,导致随着盐度的升高,总石油烃(total petroleum hydrocarbon,TPH)生物降解率加快,TPH浓度呈现出降低的趋势。微生物利用电子受体( {\mathrm{SO}}_4^{2-}、Mn、 {\mathrm{NO}}_3^{-}、Fe)降解TPH的过程中,电子受体的贡献率为:铁还原(64.88%)>锰还原(24.86%)>硫酸根还原(5.78%)>硝酸盐还原(4.46%),即加油站地下水中铁锰还原菌的石油烃生物降解为优势反应。  相似文献   

南海神狐海域水合物一维速度结构研究： 基于中—低饱和度水合物区的约束     

柳雷锋  夏少红  方允鑫  林霖  范朝焰  孙金龙  赵芳 《高校地质学报》2022,28(3):424-439

高精度OBS探测作为目前研究水合物的常用技术手段,可以获取水合物矿体精细速度结构,在研究天然气水合物饱和度、水合物资源的预测与开发等方面具有重要指导意义。然而正演模拟OBS速度结构是繁琐漫长的过程,构建合理的初始模型是后续精细结构快速成像的重要前提。本研究基于全球18个已探明地震波速度的水合物区,分析了水合物矿体内纵波速度的共性特征和影响因素,拟合了水合物矿体带纵波速度与海水深度、沉积物厚度的经验公式。综合经验公式、OBS数据与多道地震剖面,建立了神狐水合物区横向均匀初始模型,并通过射线追踪与走时拟合模拟了神狐海域的一维纵波速度结构。结果表明,神狐水合物矿体带具有高纵波速度(1.83~1.92 km/s）,游离气层具有低P波速度（1.60~1.70 km/s）,此外,基于全球的水合物速度经验公式对神狐海域速度结构模拟具有重要参考意义,有望为获取神狐海域二维/三维精确速度结构提供可靠的初始模型,进而指导水合物精细勘察与资源评估。  相似文献   

基于宽频大地电磁法的页岩气探测实践——以川西南沐川地区须家河组为例          下载免费PDF全文

杨剑  王桥  刘伟  夏时斌  张伟  廖国忠  李华  高慧 《沉积与特提斯地质》2022,42(3):444-454

四川盆地上三叠统须家河组陆相富有机质页岩较为发育,页岩连续厚度较大,含气性好,有望开辟四川盆地页岩气新区新层系。然而,复杂的人文干扰（城镇密集、人口众多）和较大的埋藏深度（2000~3000m）挑战了页岩气地球物理勘探的精度,这在很大程度上制约了川西南沐川地区三叠系须家河组页岩气的进一步勘探。本文在分析前人研究资料基础上,优选了川西南沐川地区须家河组作为新区新层系的探测目标,根据研究区地质情况,构建理论电性模型,通过正演模拟和“已知”钻孔标定方法试验,确定了宽频大地电磁法的适用性和有效性。进而在重点页岩气远景区部署一条宽频大地电磁剖面,通过数据处理分析,结合地质资料获得了研究区深部电性结构,认为研究区一带地层连续、完整,断裂不发育,具有稳定的地质结构,其中上三叠统须家河组发育较大厚度的富有机质页岩,可作为本区页岩气勘探的新区新层系,具有良好的页岩气、致密气资源前景。同时,证实了在3000m以浅页岩气探测方法中,宽频大地电磁法（BMT）可以有效地识别富有机质页岩规模和空间展布特征,是一种快速、经济、无损有效的页岩气探测方法,可以为页岩气勘探提供先导依据,同时也为同类地质情况页岩气探测提供应用示范。  相似文献   

鄂尔多斯盆地东胜富氦气田成藏特征及其大地构造背景^*          下载免费PDF全文

何发岐  王杰  赵永强  安川  王付斌  陶成  倪春华  贾会冲 《古地理学报》2022,24(5):937-950

近年来,在鄂尔多斯盆地北缘东胜气田上古生界天然气中发现伴生的氦气,含量分布在0.045%~0.487%范围内,具有工业价值,其三级储量约为8.3亿立方米,为一特大型含氦—富氦天然气田。东胜气田氦气属于典型的壳源氦,来源于基底的太古界—元古界变质岩—花岗岩系,富集与燕山期以来的岩浆侵入、断裂活动有关。东胜气田具备有利的氦气成藏地质条件,伴生氦气与烃类气具有异源同储成藏特征,剖析其成藏主控因素为: 基底富U、Th岩石发育是基础,断裂活动是核心,储盖圈保条件是必备,时空配置是关键,其中早白垩世是最重要的一期构造—岩浆热事件,深源岩浆活动导致的深部物质和热能的大规模上涌是中生代流体成藏(矿)的有利地球动力学背景,控制了鄂尔多斯盆地石炭系—二叠系煤系烃源岩大规模生气。断裂活动和圈闭形成与上古生界天然气、氦气聚集成藏具有良好的时空配置关系,与华北克拉通破坏过程耦合。鄂尔多斯地块在早白垩世至中新世深部热流体对盆地发生的多期岩浆活动、基底断裂活化及浅部断裂活动具有明显的控制作用,同时也对石炭系—二叠系煤系烃源岩成烃成藏具有重要的控制作用。  相似文献   

松辽盆地南部深层致密砂岩气储层形成机制及成藏主控因素     

张立亚  徐文  沈艳杰 《吉林大学学报(地球科学版)》2022,52(5):1707-1717

为了加快松辽盆地南部（简称松南）深层致密砂岩气勘探开发进程,开展致密砂岩储层形成机制及成藏主控因素研究。通过对松南深层致密砂岩的分析,根据致密砂岩岩性组合特征将已发现的深层致密气类型划分为稳定厚层砂型、砂泥互层型、泥包砂型3种类型,储层物性普遍差,孔隙度多小于6%,渗透率主体<0.10×10^-3 μm²,属于特低孔、特低渗储层。通过对松南典型致密储层矿物成分与微观特征的分析发现,致密砂岩有效储层形成主要受3个方面因素控制：一是早成岩期发育绿泥石包壳,有效抑制成岩中后期粒间钙质胶结、硅质胶结的发生,保护原生残余粒间孔隙;二是富火山岩岩屑溶蚀形成次生孔隙;三是生烃增压产生大量微裂缝,改善储层渗流特征。在此基础上总结出松南致密砂岩气成藏控制因素,即充足气源提供物质基础、斜坡古沟谷与断裂控砂、次生溶蚀与微裂缝控储、断裂活动与稳定盖层控富。  相似文献   

Experimental investigation of hydrate formation in water-dominated pipeline and its influential factors     

Li Huang  Jia-le Kang  Xiao-dong Shen  Jian-ye Sun  Qing-guo Meng  Qiang Chen  Gao-wei Hu  Chang-ling Liu  Neng-you Wu 《China Geology》2022,5(2):310-321

Blockage in water-dominated flow pipelines due to hydrate reformation has been suggested as a potential safety issue during the hydrate production. In this work, flow velocity-dependent hydrate formation features are investigated in a fluid circulation system with a total length of 39 m. A 9-m section pipe is transparent consisted of two complete rectangular loops. By means of pressurization with gas-saturated water, the system can gradually reach the equilibrium conditions. The result shows that the hydrates are delayed to appear as floccules or thin films covering the methane bubbles. When the circulation velocity is below 750 rpm, hydrate is finally deposited as a “hydrate bed” at upmost of inner wall, narrowing the flow channel of the pipeline. Nevertheless, no plugging is observed during all the experimental runs. The five stages of hydrate deposition are proposed based on the experimental results. It is also revealed that a higher driving pressure is needed at a lower flow rate. The driving force of hydrate formation from gas and water obtained by melting hydrate is higher than that from fresh water with no previous hydrate history. The authors hope that this work will be beneficial for the flow assurance of the following oceanic field hydrate recovery trials.©2022 China Geology Editorial Office.  相似文献   

Stability analysis of seabed strata and casing structure during the natural gas hydrates exploitation by depressurization in horizontal wells in South China Sea     

Peng-fei Xie  Lin Yang  Qian-yong Liang  Xu-hui Zhang  Liang-hua Zhang  Bin Zhang  Xiao-bing Lu  Hui-ce He  Xue-min Wu  Yi-fei Dong 《China Geology》2022,5(2):300-309

Natural gas hydrates (NGHs) are a new type of clean energy with great development potential. However, it is urgent to achieve safe and economical NGHs development and utilization. This study established a physical model of the study area using the FLAC^3D software based on the key parameters of the NGHs production test area in the South China Sea, including the depressurization method, and mechanical parameters of strata, NGHs occurrence characteristics, and the technological characteristics of horizontal wells. Moreover, this study explored the law of influences of the NGHs dissociation range on the stability of the overburden strata and the casing structure of a horizontal well. The results are as follows. With the dissociation of NGHs, the overburden strata of the NGHs dissociation zone subsided and formed funnel-shaped zones and then gradually stabilized. However, the upper interface of the NGHs dissociation zone showed significant redistribution and discontinuity of stress. Specifically, distinct stress concentration and corresponding large deformation occurred in the build-up section of the horizontal well, which was thus prone to suffering shear failure. Moreover, apparent end effects occurred at the end of the horizontal well section and might cause the deformation and failure of the casing structure. Therefore, it is necessary to take measures in the build-up section and at the end of the horizontal section of the horizontal well to prevent damage and ensure the wellbore safety in the long-term NGHs exploitation.©2022 China Geology Editorial Office.  相似文献   

Identification of functionally active aerobic methanotrophs and their methane oxidation potential in sediments from the Shenhu Area,South China Sea     

Jing Li  Chang-ling Liu  Neng-you Wu  Xiao-qing Xu  Gao-wei Hu  Yan-long Li  Qing-guo Meng 《China Geology》2022,5(2):285-292

Large amounts of gas hydrate are distributed in the northern slope of the South China Sea, which is a potential threat of methane leakage. Aerobic methane oxidation by methanotrophs, significant methane biotransformation that occurs in sediment surface and water column, can effectively reduce atmospheric emission of hydrate-decomposed methane. To identify active aerobic methanotrophs and their methane oxidation potential in sediments from the Shenhu Area in the South China Sea, multi-day enrichment incubations were conducted in this study. The results show that the methane oxidation rates in the studied sediments were 2.03–2.36 μmol/gdw/d, which were higher than those obtained by sediment incubations from other areas in marine ecosystems. Thus the authors suspect that the methane oxidation potential of methanotrophs was relatively higher in sediments from the Shenhu Area. After the incubations family Methylococcaea (type I methanotrophs) mainly consisted of genus Methylobacter and Methylococcaea_Other were predominant with an increased proportion of 70.3%, whereas Methylocaldum decreased simultaneously in the incubated sediments. Collectively, this study may help to gain a better understanding of the methane biotransformation in the Shenhu Area.©2022 China Geology Editorial Office.  相似文献