高密度电阻率法在垃圾填埋场渗漏检测中的应用

为检测垃圾填埋场的渗漏污染问题,基于垃圾填埋场渗漏污染特征,对高密度电阻率法在垃圾填埋场渗漏污染检测中的应用进行了深入研究,提出了一套获取高分辨率检测结果的工作模式和技术方法。实例证明,高密度电阻率法对于检测垃圾填埋场渗漏是一种行之有效、值得推广的技术方法。     

1000 m long gas blow-out pipes

This study presents seismic observation of pipe anomalies from offshore Nigeria, outcrops of blow-out pipes from Rhodes, Greece, and geophysical modelling of an acoustic pipe. The studies give insight into how pipes form, their internal structure, the seismic image and geophysical artefacts related to the pipes. Over one hundred seafloor craters, 100 m-700 m wide and up to 30 m deep, have been observed on the seafloor offshore Nigeria. They are underlain by interpreted cones and seismic pipe anomalies that can be traced down to reservoir zones at 1000 m-1300 m below the seafloor. The seismic pipe anomalies are 50 m-150 m wide and almost vertical. They are interpreted as up-scaled pipes found in outcrops on Rhodes, Greece. The outcrops show pipe-related structures at three levels. Lowest, the reservoir rock contains metre-sized cavities which are filled with a mixture of clay derived from the overlying cap rock. In the middle, several circular to oval structures in plane view of pipes are observed in the lowest part of the cap rock. Highest, 15 m into the clay cap rock, strongly sheared country rock forms circular structures with a core of structureless clay. Based on outcrop observation on Rhodes we constructed an acoustic model of a 50 m wide and 1000 m long pipe. Seismic modelling proves that such pipes would be expressed in seismic data, that they are similar to the seismic pipe anomalies offshore Nigeria but this study also revealed that prominent intra-pipe reflections are artefacts. A formation model for the pipes is suggested: High fluid overpressure in the reservoir generated hydro fractures from the reservoir to seafloor where a mixture of gas and fluid flowed at high speed to form pipes, cones and seafloor craters. After hours to weeks of gas and fluid flow through the pipe the pore pressure in the reservoir dropped and the blow-out terminated. Muddy slurry fell back and plugged the cavity in the reservoir and the pipe.     

二氧化碳地质存储过程中沿井筒渗漏定性分析

二氧化碳沿井筒渗漏是二氧化碳地质埋存过程中所面临的重要风险之一.尤其是对于已经封堵的废弃井,由于获取井下的信息比较困难,因此评价废弃井的完整性是一个比较大的挑战.本文为评估二氧化碳沿废弃井渗漏提出了风险分析的方法.该方法包括了三个主要步骤:渗漏方案的制定,定量模拟及结果分析.所制定的渗漏方案将通过数值模拟进行定量分析及评价.本文将阐述该评价方法的第一步骤:渗漏方案的制定.该步骤为渗漏的定量模拟提供了理论基础.该方法被广泛接受并现场应用于德国某大型二氧化碳存储及提高天然气采收率项目中.     

基坑肥槽积水对构筑物地下室的危害

随着高层建筑的大量兴建,与之配套的地下室也越挖越深,继而出现了地下室底板和外墙渗漏现象,造成了巨大的经济损失和社会影响.以贵州某高层建筑为例,在介绍场地的工程地质及水文地质条件的基础上,通过现场抽水试验过程中的水位观测,认为安装在地下室的自动泵长期抽出的水没有排到场地以外的城市排水系统中,而是在肥槽中不断循环,肥槽中水位长期高于地下水位,其积水又渗入地下室,是造成地下室底板破裂的主要原因.经过将大气降水、施工用水及工人生活用水等及时排到场外的城市排水系统中等措施,最终解决了基坑肥槽积水问题,为以后施工相似工程具有一定的借鉴作用.     

新型可固化工作液的室内研究

针对难以堵漏的恶性漏失地层和水泥封固效果不良的垮塌层,开发出新型可固化工作液。该工作液以常规钻井液为基础,具有优良的悬浮能力、流变性和抗盐能力,与钻井液相容性良好,在一定条件下能固化达到一定强度。可作为堵漏液使用,也可在井壁失稳地层作为封固液使用,能有效提高堵漏成功率和对失稳地层的封固效果。     

东升水电站导流墙固结灌浆施工工艺

根据东升水电站导流墙固结灌浆施工实践,总结了崮结灌浆过程中钻孔、裂隙冲洗、压水试验、制浆、灌浆、封孔的原则和注意事项。对灌浆过程中所遇到的漏浆及串浆特殊情况,分别采取了待凝及塞住串浆孔的措施,并取得r较好的灌浆效果。     

大宝山钼矿复杂地层钻探技术

广东大宝山钼矿区地层复杂,钻孔施工中常发生漏失、掉块、坍塌垮孔、缩径等情况,易造成钻具折断,卡钻、烧钻、埋钻等事故,且取心困难。通过选择合理的钻探工艺方法、护壁堵漏措施和钻探取心技术措施,使大宝山钼矿床和北面山多金属区详查找矿钻探工作顺利完成。详细介绍了大宝山钼矿复杂地层钻探技术。     

吸水膨胀树脂的堵漏应用效果

在唐山丰南地区进行煤田钻探施工时,由于地层裂隙发育,漏水十分严重,给钻探工作带来了许多的困难,甚至造成钻孔坍塌等事故,导致无法进行正常的生产施工。以往多用水泥、惰性材料和有机化学材料等进行堵漏,但效果欠佳。本次施工根据地层漏水的情况及特性,选用了吸水膨胀树脂进行堵漏,依据吸水膨胀树脂的高膨胀率、高强度的特点,使用了灌注法和岩心管投送法综合进行堵漏。结果表明,使用吸水膨胀树脂进行堵漏后,地层裂隙被吸水膨胀树脂完全封堵,堵塞了冲洗液的漏失通道,效果非常理想,满足了正常施工钻进的要求。     

Deciphering groundwater flow between the Complex Terminal and Plio-Quaternary aquifers in Chott Gharsa plain (southwestern Tunisia) using isotopic and chemical tools

Abstract

The Complex Terminal (CT) and Plio-Quaternary (P-Q) aquifers in the Chott Gharsa plain in southwestern Tunisia have been investigated with the aid of chemical and isotopic tools. It has been demonstrated that groundwater from the CT is mainly of palaeo-origin, especially in the western and central parts of the plain where the most negative values of δ¹⁸O and δ²H were observed (between??8.1 and??7.6‰ for δ¹⁸O, and??60 to??57‰ for δ²H), combined with low concentrations of radiocarbon (6.8–7.5 pmc) and absence of tritium. Modern recharge of the aquifer occurs only in the eastern part of the system where younger waters were observed, as indicated by their stable isotope composition, relatively high radiocarbon content and presence of tritium. Groundwater from the P-Q multi-layer aquifer represents mixtures of ascending deep CT waters and modern water recharging the P-Q aquifer system. Isotope mass balance was used to quantify mixing proportions. The calculations showed that the contribution of deep CT groundwater to the P-Q aquifer system reaches about 75% in the western and central parts of the plain where the CT aquifer remains strongly artesian. This contribution decreases to about 15% towards the eastern part of the plain, as a consequence of significant reduction of artesian pressure in this area of the CT aquifer. Chemical data suggest that mineralization of the studied groundwater systems is controlled mainly by dissolution of evaporative minerals (halite, anhydrite and gypsum) and cation exchange reactions with the matrix, possibly enhanced by recent anthropogenic disturbance of the system caused by lowering of the water table due to heavy exploitation and return flow of saline irrigation water into the P-Q aquifer.

Editor D. Koutsoyiannis; Associate editor E. Custodio

Citation Yangui, H., Abidi, I., Zouari, K., and Rozanski, K., 2012. Deciphering groundwater flow between the Complex Terminal and Plio-Quaternary aquifers in Chott Gharsa plain (southwestern Tunisia) using isotopic and chemical tools. Hydrological Sciences Journal, 57 (5), 967–984.     

Early detection of brine and CO2 leakage through abandoned wells using pressure and surface-deformation monitoring data: Concept and demonstration

In this paper, we develop a methodology for early detection of potential CO₂ leakage from geological storage formations using pressure and surface-deformation anomalies. The basic idea is based on the fact that leakage-induced pressure signals travel much faster than the migrating CO₂; thus such anomalies may be detected early enough for risk management measures taking effect in avoiding substantial CO₂ leaks. The early detection methodology involves automatic inversion of anomalous brine leakage signals with efficient forward pressure and surface-deformation modeling tools to estimate the location and permeability of leaky features in the caprock. We conduct a global sensitivity analysis to better understand under which conditions pressure anomalies can be clearly identified as leakage signals, and evaluate signal detectability for a broad parameter range considering different detection limits and levels of data noise. The inverse methodology is then applied to two synthetic examples of idealized two-aquifer-and-one aquitard storage systems, with an injection well and a leaky well, for different monitoring scenarios. In Example 1, only pressure data at the monitoring and injection wells are used for leakage detection. Our results show that the accuracy of leakage detection greatly depends on the level of pressure data noise. In Example 2, joint inversion of pressure and surface-deformation measurements significantly improves the speed of convergence toward the true solution of the leakage parameters and enables early leakage detection. In both examples, successful detection is achieved when two monitoring wells are appropriately placed within up to 4 km from the leaky well.