Larry Murdoch

Feasibility of electrokinetic soil remediation in horizontal Lasagna™ cells ☆

An integrated soil remediation technology called Lasagna has been developed that combines electrokinetics with treatment zones for use in low permeability soils where the rates of hydraulic and electrokinetic transport are too low to be useful for remediation of contaminants. The technology was developed by two groups, one involving industrial partners and the DOE and another involving US EPA and the University of Cincinnati, who pursued different electrode geometries. The Industry/DOE group has demonstrated the technology using electrodes and treatment zones installed vertically from the soil surface. We have demonstrated the feasibility of installing horizontal electrodes and treatment zones in subsurface soils by hydraulic fracturing, a process that we adapted from petroleum industry practices. When horizontal electrodes were connected to a dc power supply, uniform electrical potential gradients of 10-40 V/m were created in soil between the electrodes, inducing electroosmotic flow that facilitated movement of water and contaminants into treatment zones between the electrodes.

Community Modeling in Hydrologic Science: Scoping Workshop on a Community Hydrologic Modeling Platform (CHyMP); Washington, D.C., 26–27 March 2008

As one of two major new initiatives for its next 5-year phase, the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI), is proposing to launch a major effort toward the development of a Community Hydrologic Modeling Platform (CHyMP), which will support a range of research and applications in water cycle science.

Hydrogeology of the vicinity of Homestake mine, South Dakota, USA

The former Homestake mine in South Dakota (USA) cuts fractured metamorphic rock over a region several km2 in plan, and plunges to the SE to a depth of 2.4 km. Numerical simulations of the development and dewatering of the mine workings are based on idealizing the mine-workings system as two overlapping continua, one representing the open drifts and the other representing the host rock with hydrologic properties that vary with effective stress. Equating macroscopic hydrologic properties with characteristics of deformable fractures allows the number of parameters to be reduced, and it provides a physically based justification for changes in properties with depth. The simulations explain important observations, including the co-existence of shallow and deep flow systems, the total dewatering flow rate, the spatial distribution of in-flow, and the magnitude of porosity in the mine workings. The analysis indicates that a deep flow system induced by ~125 years of mining is contained within a surface-truncated ellipsoid roughly 8 km by 4 km in plan view and 5.5 km deep with its long-axis aligned to the strike of the workings. Groundwater flow into the southern side of the workings is characterized by short travel times from the ground surface, whereas flow into the northern side and at depth consists of old water removed from storage.RésuméL’ancienne Homestake mine, Sud Dakota (USA), recoupe une roche métamorphique fracturée s’étendant sur une surface de plusieurs km2, plongeant au SE à une profondeur de 2.4xa0km. Les simulations numériques du développement et du dénoyage des travaux miniers sont basés sur une figuration idéale du système, le schématisant comme deux continua chevauchants, l’un représentant les milieux dépilés, l’autre représentant la roche encaissante avec des propriétés hydrologiques variant selon la tension effective. L’équivalence des propriétés macroscopiques hydrologiques et des caractéristiques de fractures déformables permet de réduire le nombre de paramètres et fournit une base physique justifiant les changements de propriétés avec la profondeur. Les simulations expliquent des observations remarquables, incluant la coexistence de systèmes de flux profonds et superficiels, le flux total de dénoyage, la distribution spatiale de l’ennoyage et le volume de porosité dans les travaux miniers. L’analyse indique qu’un système de flux profond induit par environ 125 années d’exploitation est contenu à l’intérieur d’un ellipsoïde tronqué d’environ 8 kmxa0×xa04 km en projection horizontale et 5.5 km en souterrain avec son axe principal dirigé suivant le pendage des travaux. Le flux d’eau souterraine dans la partie Sud des travaux est caractérisé par des temps de transfert courts depuis la surface du sol, alors que du côté Nord et en profondeur il mobilise de l’eau d’accumulation ancienne.ResumenLa antigua mina Homestake en Dakota del Sur (EEUU) corta rocas metamórficas fracturadas sobre una región de estudio de varios km2, y se hunde hacia el SE a una profundidad de 2.4 km. Las simulaciones numéricas del desarrollo y drenaje de los laboreos mineros se basan en la idealización de los sistemas de laboreos como la superposición de dos continuos, uno que representa las labores abiertas y el otro que representa a la roca hospedante con propiedades hidrológicas que varían con la tensión efectiva. La equiparación de las propiedades hidrológicas macroscópicas con las características de las fracturas deformables permite que el número de parámetros sea reducido, y proporciona una justificación basada físicamente para los cambios de las propiedades con la profundidad. La simulación explica observaciones importantes, incluyendo la coexistencia de sistemas de flujos someros y profundos, el ritmo del flujo total de drenaje, la distribución espacial del flujo entrante, y la magnitud de la porosidad en los laboreos de la mina. El análisis indica que un sistema de flujo profundo inducido por 125 años de minería está contenido dentro de un elipsoide truncado en superficie de aproximadamente 8 kmxa0por 4 km en la vista en planta y 5.5 km de profundidad con su eje largo alineado al rumbo de los laboreos. El flujo de agua subterránea hacia el lado sur de los laboreos está caracterizado por tiempos de tránsito cortos a partir de la superficie del terreno, mientras que el flujo hacia el lado norte y en profundidad consiste de agua vieja removida del almacenamiento.摘要美国南达科他州的前Homestake矿切割了数平方公里区域范围内的破碎的变质岩, 该变质岩向东南倾伏至2.4km深度处。本次井巷的开采和排水数值模拟假设围岩是均一、各向异性、双孔双渗透率连续体模型, 且其水文地质特征随有效应力变化。将宏观水文地质条件和变化裂隙的性质等同, 能减少参数的数量, 并能为随深度变化的性质提供基于物理性质的调整。模拟解释了重要的观测现象, 包括浅部和深部地下水流动系统的共存, 总排水速率, 内部水流和矿山巷道中孔隙度大小的空间分布。分析表明由125年采矿造成的深部地下水流动系统位于一个平面视图看面积约为8km×4km面积, 深度为5.5km的椭球体中, 且其短轴方向与巷道的走向一致。巷道南部的地下水流是来自地表的年龄较轻的水, 而补给到北部一定深度的水则是来自于储层中的老水。ResumoA antiga mina de Homestake, em Dakota do Sul (EUA), encontra-se instalada em rochas metamórficas fracturadas, numa área de vários km2, e inclina para SE até uma profundidade de 2.4 km. Simulações numéricas da exploração e drenagem da mina baseiam-se na idealização de um sistema de funcionamento da mina como dois meios sobrepostos contínuos, um representando as galerias abertas e outro representando a rocha hospedeira, com propriedades hidrológicas que variam com a tensão efectiva. A comparação das propriedades hidrológicas macroscópicas com as características das fracturas deformáveis permite a redução do número de parâmetros e proporciona uma justificação fisicamente fundamentada para as alterações das propriedades em profundidade. As simulações explicam observações importantes, tais como a coexistência de sistemas de fluxo de pequena e grande profundidade, a velocidade do fluxo da drenagem, a distribuição espacial das entradas de água e a magnitude da porosidade nos trabalhos mineiros. A análise revela que existe um sistema de fluxo profundo induzido por cerca de 125 anos de exploração mineira, que se encontra confinado dentro de um elipsóide truncado à superfície, com uma área em planta de cerca de 8 por 4 km e atingindo 5.5 km de profundidade, com o seu eixo longo alinhado com a orientação da exploração da mina. A entrada de água subterrânea no lado sul da mina é caracterizada por tempos de trânsito curtos a partir da superfície, enquanto a entrada pelo lado norte e em profundidade provém de água antiga removida do armazenamento.

Proof-of-feasibility of using well bore deformation as a diagnostic tool to improve CO2 sequestration

Injecting CO2 raises pore pressure and this causes subsurface formations to deform. The pattern and amount of deformation will reflect the distribution of pressure and formation properties in the subsurface, two quantities of interest during CO2 storage. The hypothesis underlying this research is that the small deformation accompanying CO2 storage can be measured and interpreted to improve the storage process.