The application of moment methods to the analysis of fluid electrical conductivity logs in boreholes

Loew, Simon; Tsang, Chin‐Fu; Hale, F.V.; Hufschmied, Peter

doi:10.2172/6365667

Cited by 3 publications

(1 citation statement)

References 6 publications

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“…Several integral approaches have been developed (Tsang and Hale, 1989;Loew et al, 1990) that can provide good initial guesses to BORE, greatly enhancing its ease of use. However, these methods are limited to wellbore sections containing inflow points only.…”

Section: Introductionmentioning

confidence: 99%

Inflow and outflow signatures in flowing wellbore electrical conductivity logs

Doughty¹,

Tsang²

2002

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Flowing wellbore electrical-conductivity logging provides a means to determine hydrologic properties of fractures, fracture zones, or other permeable layers intersecting a borehole in saturated rock. The method involves analyzing the time-evolution of fluid electricalconductivity logs obtained while the well is being pumped and yields information on the location, hydraulic transmissivity, and salinity of permeable layers, as well as their initial (or ambient) pressure head. Earlier analysis methods were restricted to the case in which flows from the permeable layers or fractures were directed into the borehole. More recently, a numerical model for simulating flowing-conductivity logging was adapted to permit treatment of both inflow and outflow, including analysis of natural regional flow in the permeable layer. However, determining the fracture properties with the numerical model by optimizing the match to the conductivity logs is a laborious trial-and-error procedure. In this paper, we identify the signatures of various inflow and outflow features in the conductivity logs to expedite this procedure and to provide physical insight for the analysis of these logs. Generally, inflow points are found to produce a distinctive signature on the conductivity logs themselves, enabling the determination of location, inflow rate, and ion concentration in a straightforward manner.Identifying outflow locations and flow rates, on the other hand, can be done with a more complicated integral method. Running a set of several conductivity logs with different pumping rates (e.g., half and double the original pumping rate) provides further information on the nature of the feed points. In addition to enabling the estimation of flow parameters from conductivity logs, an understanding of the conductivity log signatures can aid in the design of follow-up logging activities.1

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Section: Introductionmentioning

confidence: 99%

Inflow and outflow signatures in flowing wellbore electrical conductivity logs

Doughty¹,

Tsang²

2002

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Signatures in flowing fluid electric conductivity logs

Doughty¹,

Tsang²

2005

Journal of Hydrology

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Laboratory and numerical evaluation of borehole methods for subsurface horizontal flow characterization.

Pedler¹,

Jepsen

2003

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The requirement to accurately measure subsurface groundwater flow at contaminated sites, as part of a time and cost effective remediation program, has spawned a variety of flow evaluation technologies. Validation of the accuracy and knowledge regarding the limitations of these technologies are critical for data quality and application confidence. Leading the way in the effo rt to validate and better understand these methodologies, the US Army Environmental Center has funded a multi-year program to compare and evaluate all viable horizontal flow measurement technologies. This multi-year program has included a field comparison phase, an application of selected methods as part of an integrated site characterization program phase, and most recently, a laboratory and numerical simulator phase.As part of this most recent phase, numerical modeling predictions and laboratory measurements were made in a simulated fracture borehole set-up within a controlled flow simulator. The scanning colloidal borescope flowmeter (SCBFM) and advanced hydrophysical 4 logging (NxHpL™) tool were used to measure velocities and flow rate in a simulated fractured borehole in the flow simulator. Particle tracking and mass flux measurements were observed and recorded under a range of flow conditions in the simulator. Numerical models were developed to aid in the design of the flow simulator and predict the flow conditions inside the borehole.Results demonstrated that the flow simulator allowed for predictable, easily controlled, and stable flow rates both inside and outside the well. The measurement tools agreed well with each other over a wide range of flow conditions. The model results demonstrate that the Scanning Colloidal Borescope did not interfere with the flow in the borehole in any of the tests. The model is capable of predicting flow conditions and agreed well with the measurements and observations in the flow simulator and borehole. Both laboratory and model results showed a lower limit of fracture velocity in which inflow occurs, but horizontal flow does not establish itself in the center of the borehole. In addition, both laboratory and model results showed circulation cells in the borehole above and below the fracture horizon. The length of the interval over which the circulating cells occurred was much larger than the interval of actual horizontal flow. These results suggest that for the simple fracture geometry simulated in this study, horizontal flow can be predictable and measurable, and that this flow is representative of the larger, near-field flow system. Additional numerical refinements and laboratory simulations of more robust, life-like fracture geometries should be considered.The preliminary conclusions of this work suggest the following: 1) horizontal flow in the fractured medium which is representative of the near-field flow conditions can be established in a wellbore; 2) this horizontal flow can be accurately measured and numerically predicted; 3) the establishment of directionally quantifiable horizontal fl...

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The application of moment methods to the analysis of fluid electrical conductivity logs in boreholes

Cited by 3 publications

References 6 publications

Inflow and outflow signatures in flowing wellbore electrical conductivity logs

Inflow and outflow signatures in flowing wellbore electrical conductivity logs

Signatures in flowing fluid electric conductivity logs

Laboratory and numerical evaluation of borehole methods for subsurface horizontal flow characterization.

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