Field techniques using borehole packers in hydrogeological investigations

Abstract

Summary As part of a hydrogeological investigation in a Permo-Triassic Sandstone aquifer in northwest England, various methods of field permeability testing have been developed and evaluated. These techniques involve the use of borehole packers to isolate specific test sections and permeability measurements made by either injection or pumping tests. Field results have been compared with both laboratory permeability measurements and conventional pumping tests. The test procedures were found to have a significant effect on the results obtained. Packers have also been employed to examine the vertical distribution of piezometric heads within an aquifer, both in pumping and non-pumping conditions, and to obtain groundwater samples from selected horizons. Some of the test results are presented to illustrate the value of packer techniques in hydrogeological investigations.

The effects of climate changes on aquifer storage and river baseflow

“…For the Triassic sandstone aquifer, setting Tto 90 m 2 day" 1 , S to 0.1 and L to 3000 m gave Ta = 0.0001 day" 1 . The assumption of constant transmissivity over the width of the aquifer is believed reasonable for the Triassic sandstone (Brassington & Walthall, 1985) and has been retained here, with the same values of Ta used in the dimensionless analysis.…”

Sedimentary flow heterogeneities in the Triassic U.K. Sherwood Sandstone Group: Insights for hydrocarbon exploration

“…Permeability at the well test scale at shallow depths (<150 m below ground level [BGL], i.e., as reflected by transmissivity from pumping tests) does not show a clear correlation with rates of tectonic subsidence and accommodation generation. Transmissivity values in the Sherwood Sandstone Group show similar values across Great Britain, that is, median values ranging from 100 up to 300 m 2 /day in the various Triassic basins (Allen et al, ; Brassington & Walthall, ; Medici et al, ). The presence of conductive fractures in the U.K. Sherwood Sandstone aquifer at depths <150 m below the ground surface typically precludes linkage between transmissivity and lithofacies.…”

“…The presence of conductive fractures in the U.K. Sherwood Sandstone aquifer at depths <150 m below the ground surface typically precludes linkage between transmissivity and lithofacies. For example, the fluvial St Bees Sandstone ( T = 20–750 m 2 /day) and the aeolian Calder Sandstone ( T = 100–210 m 2 /day) aquifers in the eastern Irish Sea Basin, which are characterized by significantly different porosities and core‐plug‐scale permeability (Figure b) values, show substantial overlap in well‐test‐derived transmissivity (Allen et al, ; Brassington & Walthall, ; McKie & Williams, ; Medici et al, , ; Tellam & Barker, ). Despite this, intergranular flow dominates in the Sherwood Sandstone aquifer under circumstances of either (a) particularly high intergranular porosity (eastern England Shelf) or (b) a reduction of fracture flow with the increasing depth and lithostatic load (eastern Irish Sea Basin).…”

“…Core-plug-scale hydraulic conductivity (see K h and K v values annotated in Figure 7a) also significantly reduces (~70%) northward from the pebbly sandstone lithofacies (LA1) of Nottinghamshire to the fine-to medium-grained sandstone (LA2) of the North Sea coast, in response to the coupling of grain size and porosity reduction moving northward (Allen et al, 1997). Britain, that is, median values ranging from 100 up to 300 m 2 /day in the various Triassic basins (Allen et al, 1997;Brassington & Walthall, 1985;Medici et al, 2016). overlap in well-test-derived transmissivity (Allen et al, 1997;Brassington & Walthall, 1985;McKie & Williams, 2009;Medici et al, 2016Medici et al, , 2018Tellam & Barker, 2006).…”

The value and interpretation of groundwater level measurements

“…The problem with the unreliability of water level readings in open boreholes in fissured aquifers has been discussed by Rushton & Howard (1982) and by Walthall & Ingram (1984) for the Permo-Triassic Sandstone at Kenyon Junction where the different layers within the aquifer were only identified after the installation of multiple piezometers. The presence of different piezometric heads within what at first sight appears to be a uniform aquifer has also been demonstrated by the use of borehole packers (Brassington 1985) and also by a combined multiple packer/piezometer installation. The effects are important in the interpretation of the response of the aquifer to any development, and in particular to interpreting whether it will show an unconfined or confined response.…”