Experiments to Assess the Hydraulic Efficiency of Well Screens

Abstract

The hydraulic properties of commercial well screens were investigated to determine which screen design features affected head loss. The test program began with laboratory experiments and continued as a field‐scale experiment with the installation of a well field in the Thames Valley Gravel Aquifer. The laboratory experiments indicated that, for all practical purposes, the head loss attributable to all of the screens tested was negligible. The experimental head loss, however, did vary from screen to screen, particularly at high intake velocities, and the screens could be ranked on the basis of their hydraulic efficiencies. This efficiency hierarchy is explained tentatively in terms of the screen construction methods and slot geometry. The field experiments showed that the hydraulic performance of all well screens is independent of screen design provided that the open area of the screen is above about 10%. The field experiments also indicated that the development capacity of a screen in a gravel aquifer is not wholly dependent on screen design, but that progressive development does increase the hydraulic efficiency of a well.

Review: Hydraulics of water wells—head losses of individual components

“…Example calculations with the different equations listed in the preceding, experimental studies, field tests and numerical modeling all agree that, at least within typical parameter sets, screen head losses are usually in the range of a few millimeters to a few centimeters and can safely be ignored, when compared to the contributions of other components (e.g., Clark and Turner 1983;Roscoe Moss 1990;Barker and Herbert 1992a;Parsons 1994;Klauder 2010;Houben and Hauschild 2011). It is a little sad to think that the component to which engineers have devoted so many ideas and so much skill in design and manufacture, plays the smallest role.…”

“…A second group of authors prefer turbulent approaches to describe flow through screens (e.g., Clark and Turner 1983;Singh and Shakya 1989;Barker and Herbert 1992a, b;Parsons 1994). Clark and Turner (1983) performed laboratory experiments and field tests on the hydraulic performance of different screens with an open area ranging from 5 to 40 %.…”

“…Clark and Turner (1983) performed laboratory experiments and field tests on the hydraulic performance of different screens with an open area ranging from 5 to 40 %. They were able to fit the experimental results with Eq.…”

“…Appendix Notation a f frictional head loss factor screen a j joint coefficient (a j =2 for box and pin joints, a j =1.5 for nipple joints) full aquifer thickness (L) C constant (numerical value) C c coefficient of contraction, typically ≈ 0.6 C CT fit parameter used by Clark and Turner (1983) (L −1 /T −2 ) C sl circumference of screen slot (L) C v velocity coefficient≈0.98 for slots d diameter (L) Constants g 9.81 m/s 2 ρ ρ w =1000 kg/m 3 μ 0.001 kg/s·m ν 1.01·10 −6 m 2 /s…”

A drive point application of the Guelph Permeameter method for coarse-textured soils

“…Numerical simulations were used in this study to obtain C DP (Section 2.2), and it was assumed that drive point screen porosity was ≥10% so that screeninduced flow impedance and head loss were negligible (Clark and Turner, 1983). …”