Integrated borehole logging methods for wellhead protection applications

Hydrochemical borehole logs characterizing fluoride contamination in a crystalline aquifer (Maheshwaram, India)

“…They control the hydrodynamic properties of an aquifer as well as the transport of solutes and the dispersal of contaminants. Several methods can help determining the variability of permeability, or imaging the structure of the main flow zones in an aquifer around boreholes; these include geophysical and imaging logs, fluid logs-particularly temperature, conductivity and flow logs-as well as packer tests (Keys, 1990; Barton et al, 1995;Paillet and Pedler, 1996;Berkowitz, 2002;Schurch and Buckley, 2002;Maréchal et al, 2004;Kumar et al, 2007;Le Borgne et al, 2007;Chatelier et al, 2011;Dewandel et al, 2012). Whatever the geological context, the use of hydrochemical logging is less common, but has proved relevant for characterizing a heterogeneous aquifer (Schurch and Buckley, 2002;Schurch and Vuataz, 2002).…”

Signatures in flowing fluid electric conductivity logs

“…Of the various downhole methods for determining fracture flow that have been developed over the past few decades (National Research Council Committee on Fracture Characterization and Fluid Flow, 1996, Chapter 4), flowing fluid electric conductivity (FEC) logging has proven to be quite successful. Since Tsang et al (1990) introduced the method, it has been applied in deep wells to depths of 1500 m or more (Kelley et al, 1991;Guyonnet et al, 1993), in inclined boreholes drilled in the underground Grimsel Test Laboratory (Marschall and Vomvoris, 1995), and extensively in shallower wells of 100 m or less (Evans et al, 1992;Pedler et al, 1992;Bauer and LoCoco, 1996;Paillet and Pedler, 1996;Karasaki et al, 2000). In the flowing FEC logging method, wellbore water is first replaced by de-ionized water or, alternatively, water of a constant salinity distinctly different from that of the formation water.…”

“…In contrast, standard static FEC (or resistivity) logs reflect variations in formation salinity, but provide no information on flow conditions. Furthermore, under a wide range of conditions, the flowing FEC logging method has been found to be more accurate than spinner flow meters and much more efficient and less costly than packer tests, the two traditional means of assessing hydraulic transmissivity Paillet and Pedler, 1996;Karasaki et al, 2000). Spinner flow meters are very sensitive to variations in wellbore radius, because they measure a local fluid velocity that is inversely proportional to wellbore radius squared.…”

Flowing fluid electric conductivity logging for a deep artesian well in fractured rock with regional flow

“…Flow-logging techniques are an attractive alternative -they measure flow directly and are efficient to deploy in the field. Several varieties of flow logging exist, including spinner surveys (Molz et al, 1989), heat-pulse flowmeters (Öhberg and Rouhiainen, 2000;Paillet, 1998;Paillet and Pedler, 1996), tracer dilution analysis (Brainerd and Robbins, 2004), and the flowing fluid electric conductivity (FFEC) logging method, the technique employed in the present study.…”

“…By fitting the growth and movement of these peaks with a simple numerical model, one can infer inflow strengths and salinities of individual permeable features intersected by the borehole. Since Tsang et al (1990) introduced the method, it has been widely applied in deep wells down to 1500 m or more (Doughty et al, , 2008Guyonnet et al, 1993;Kelley et al, 1991;Löw et al, 1994), in inclined boreholes drilled in the underground Grimsel Test Laboratory (Marschall and Vomvoris, 1995), and extensively in shallower wells down to about 100 m (Bauer and LoCoco, 1996;Evans, 1995;Evans et al, 1992;Karasaki et al, 2000;Paillet and Pedler, 1996;Pedler et al, 1992). Continued development of analytical and numerical data-analysis techniques (e.g., has broadened the range of applicability and enhanced the ease of use of the method.…”