Application of Electromagnetic Logging to Contamination Investigations in Glacial Sand‐and‐Gravel Aquifers

Williams, John H.; Lapham, Wayne W.; Barringer, Thomas H.

doi:10.1111/j.1745-6592.1993.tb00082.x

Cited by 23 publications

(8 citation statements)

References 4 publications

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“…Specific conductance in wells was measured in situ with a downhole probe along the screen interval and compared to measurements from the corresponding ESASS profile. Water electrical conductivity from the ESASS profile also was compared to a borehole electromagnetic (EM) conductivity log that was collected within the installed well by methods described by Williams et al (1993). EM logs measure the bulk electrical conductivity of the aquifer outside the well and can be used to profile along cased and uncased sections of the well.…”

Section: Waste Sitementioning

confidence: 99%

Application of a New Vertical Profiling Tool (ESASS) for Sampling Groundwater Quality During Hollow‐Stem Auger Drilling

Harte¹,

Flanagan²

2011

Groundwater Monitoring Rem

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A new tool called ESASS (Enhanced Screen Auger Sampling System) was developed by the U.S. Geological Survey. The use of ESASS, because of its unique U.S. patent design (U.S. patent no. 7,631,705 B1), allows for the collection of representative, depth‐specific groundwater samples (vertical profiling) in a quick and efficient manner using a 0.305‐m long screen auger during hollow‐stem auger drilling. With ESASS, the water column in the flights above the screen auger is separated from the water in the screen auger by a specially designed removable plug and collar. The tool fits inside an auger of standard inner diameter (82.55 mm). The novel design of the system constituted by the plug, collar, and A‐rod allows the plug to be retrieved using conventional drilling A‐rods. After retrieval, standard‐diameter (50.8 mm) observation wells can be installed within the hollow‐stem augers. Testing of ESASS was conducted at one waste‐disposal site with tetrachloroethylene (PCE) contamination and at two reference sites with no known waste‐disposal history. All three sites have similar geology and are underlain by glacial, stratified‐drift deposits. For the applications tested, ESASS proved to be a useful tool in vertical profiling of groundwater quality. At the waste site, PCE concentrations measured with ESASS profiling at several depths were comparable (relative percent difference <25%) to PCE concentrations sampled from wells. Vertical profiling with ESASS at the reference sites illustrated the vertical resolution achievable in the profile system; shallow groundwater quality varied by a factor of five in concentration of some constituents (nitrate and nitrite) over short (0.61 m) distances.

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Section: Waste Sitementioning

confidence: 99%

Application of a New Vertical Profiling Tool (ESASS) for Sampling Groundwater Quality During Hollow‐Stem Auger Drilling

Harte¹,

Flanagan²

2011

Groundwater Monitoring Rem

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“…EM probes are more sensitive when bulk aquifer resistivity is low and less sensitive when the aquifer resistivity is high; therefore, EM logging is best suited for use in aquifers intruded by sea water or other strong brines that provide a large resistivity contrast with aquifer materials (Keys 1990). Therefore, changes in bulk EM resistivity measured during sequential EM logging of wells can only be caused by changes in groundwater quality (Williams et al 1993). In most cases, the EM properties of the aquifer materials are unknown or uncertain; however, aquifer lithology remains constant through time (neglecting possible changes caused by subsidence).…”

Section: Introductionmentioning

confidence: 99%

“…In most cases, the EM properties of the aquifer materials are unknown or uncertain; however, aquifer lithology remains constant through time (neglecting possible changes caused by subsidence). Therefore, changes in bulk EM resistivity measured during sequential EM logging of wells can only be caused by changes in groundwater quality (Williams et al 1993). Collection of sequential EM logs in a well over time eliminates the uncertainty associated with the estimation of the EM properties of aquifer materials and can provide an estimate of the relative changes in groundwater quality with time.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic‐Induction Logging to Monitor Changing Chloride Concentrations

Metzger

Izbicki

2012

Groundwater

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Water from the San Joaquin Delta, having chloride concentrations up to 3590 mg/L, has intruded fresh water aquifers underlying Stockton, California. Changes in chloride concentrations at depth within these aquifers were evaluated using sequential electromagnetic (EM) induction logs collected during 2004 through 2007 at seven multiple-well sites as deep as 268 m. Sequential EM logging is useful for identifying changes in groundwater quality through polyvinyl chloride-cased wells in intervals not screened by wells. These unscreened intervals represent more than 90% of the aquifer at the sites studied. Sequential EM logging suggested degrading groundwater quality in numerous thin intervals, typically between 1 and 7 m in thickness, especially in the northern part of the study area. Some of these intervals were unscreened by wells, and would not have been identified by traditional groundwater sample collection. Sequential logging also identified intervals with improving water quality-possibly due to groundwater management practices that have limited pumping and promoted artificial recharge. EM resistivity was correlated with chloride concentrations in sampled wells and in water from core material. Natural gamma log data were used to account for the effect of aquifer lithology on EM resistivity. Results of this study show that a sequential EM logging is useful for identifying and monitoring the movement of high-chloride water, having lower salinities and chloride concentrations than sea water, in aquifer intervals not screened by wells, and that increases in chloride in water from wells in the area are consistent with high-chloride water originating from the San Joaquin Delta rather than from the underlying saline aquifer.

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“…Numerous field studies (e.g., Williams et al 1993;Stone et al 1996) have demonstrated the value and utility of using borehole geophysical logs to directly determine the hydrogeologic characteristics of ground water systems. Geophysical logs from multiple wells yield in situ measurements of fluid and rock properties as funcau.s.…”

Section: Introductionmentioning

confidence: 99%

Fractured‐Aquifer Hydrogeology from Geophysical Logs: Brunswick Group and Lockatong Formation, Pennsylvania

2000

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The Brunswick Group and the underlying Lockatong Formation are composed of lithified Mesozoic sediments that constitute part of the Newark Basin in southeastern Pennsylvania. These fractured rocks form an important regional aquifer that consists of gradational sequences of shale, siltstone, and sandstone, with fluid transport occurring primarily in fractures. An extensive suite of geophysical logs was obtained in seven wells located at the borough of Lansdale, Pennsylvania, in order to better characterize the areal hydrogeologic system and provide guidelines for the refinement of numerical ground water models. Six of the seven wells are approximately 120 m deep and the seventh extends to a depth of 335 m. Temperature, fluid conductivity, and flowmeter logs are used to locate zones of fluid exchange and to quantify transmissivities. Electrical resistivity and natural gamma logs together yield detailed stratigraphic information, and digital acoustic televiewer data provide magnetically oriented images of the borehole wall from which almost 900 fractures are identified.Analyses of the geophysical data indicate that the aquifer penetrated by the deep well can be separated into two distinct structural domains, which may, in turn, reflect different mechanical responses to basin extension by different sedimentary units:1. In the shallow zone (above 125 m), the dominant fracture population consists of gently dipping bedding plane partings that strike N46°E and dip to the northwest at about 11 degrees. Fluid flow is concentrated in the upper 80 m along these subhorizontal fractures, with transmissivities rapidly diminishing in magnitude with depth.2. The zone below 125 m marks the appearance of numerous high-angle fractures that are orthogonal to the bedding planes, striking parallel but dipping steeply southeast at 77 degrees.This secondary set of fractures is associated with a fairly thick (approximately 60 m) high-resistivity, low-transmissivity sandstone unit that is abruptly terminated by a thin shale bed at a depth of 190 m. This lower contact effectively delineates the aquifer's vertical extent at this location because no detectable evidence of ground water movement is found below it. Thus, fluid flow is controlled by fractures, but fracture type and orientation are related to lithology. Finally, a transient thermal-conduction model is successfully applied to simulate observed temperature logs, thereby confirming the effects of ground-surface warming that occurred in the area as a result of urbanization at the turn of the century. The systematic warming of the upper 120 m has increased the transmissivity of this aquifer by almost 10%, simply due to changes in fluid viscosity and density.

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Application of Electromagnetic Logging to Contamination Investigations in Glacial Sand‐and‐Gravel Aquifers

Cited by 23 publications

References 4 publications

Application of a New Vertical Profiling Tool (ESASS) for Sampling Groundwater Quality During Hollow‐Stem Auger Drilling

Application of a New Vertical Profiling Tool (ESASS) for Sampling Groundwater Quality During Hollow‐Stem Auger Drilling

Electromagnetic‐Induction Logging to Monitor Changing Chloride Concentrations

Fractured‐Aquifer Hydrogeology from Geophysical Logs: Brunswick Group and Lockatong Formation, Pennsylvania

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