Well Screens and Gravel Packs^a

Abstract

The purpose of well screens and gravel packs is to maintain open access within the aquifer ensuring that thorough development of the well is not impeded by sand. Where a well draws on unconsolidated sands and gravels, or other friable materials, the installation of a screen and pack is essential. The use of correctly designed equipment is important and this paper represents a review of the diverse types available, but does not set out to make any recommendations. Well screen designs should incorporate the following features: Minimum entrance velocity. Maximum open area of screen. Correct design of slots to minimize blockages. Slot size should match aquifer or gravel pack medium. Screen material should be corrosion resistant. Screen should allow for periodic maintenance. Commercial well screens fall into various categories according to their slot designs. A slot shape, offering the maximum open area consistent with strength, is a priority and the material used in screen manufacture has an important bearing on this. Blockage of screens may be caused by chemical deposition formed by precipitation or corrosion products, and coated screens have been introduced seeking to inhibit this. Gravel packs should include the following design features: Sand free operation after development. Give lowest possible resistance to permeation. Offer low entrance velocities. Be resistant to chemical attack and have an efficient service life. The gravel pack should ensure that the completed well operates free of sand; thus the particle size of the pack depends upon the particle size of the aquifer. Gravel pack design should be guided by standard sieve analysis. It is evident from the variety of claims made for well screens and gravel packs that further research is necessary. It is suggested that the following points need further investigation: Improved design of nonblocking opening. Design consideration of screen resistance to chemical attack. Best type of gravel and optimum thickness of the pack. Head loss through the screen and pack.

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

“…The same applies to later rehabilitations: a permeable pack allows hydraulic energy applied in the well interior to be transmitted to the borehole wall. Standard procedures of gravel pack design, especially the selection of grain size, are described in detail in, e.g., Blair (1970); Driscoll (1986); Roscoe Moss (1990); ADITCL (1996) and Sterrett (2007). Drilling companies often tend to be affected by Bgravel pack angst^and use finer pack grain sizes than required.…”

Sulama Kuyularında Filtre Uzunluğunun Bazı Pompaj Parametrelerine Etkisi

“…Suyun filtreye giriş hızı aşağıdaki eşitlik yardımıyla hesaplanmıştır. Filtre deliklerinin tıkanma oranı %50 olarak alınmıştır (Blair, 1970;Moss, 1982;Clark ve Turner, 1983;Boman ve ark., 2003;Fulton ve ark., 2004;Strickland ve Korleski, 2006;Delleur, 2010;Mahasneh, 2015). v 1 (cm s -1 ) = [(Q/3600)/A]*100 A=π*D*L*DO*TO Burada; Q debi (m 3 h -1 ), A filtrenin toplam delik alanı (m 2 ), D filtre çapı (m), L filtre uzunluğu (m), DO desimal olarak filtrenin delik alanı, TO delik tıkanma oranlarını ifade etmektedir.…”

INV-FLOW: New Possibilities to Evaluate the Technical Condition and Function of Extraction Wells

“…The main parameters of the gravel pack are the grain size, width, and material type [8]. These parameters are selected depending on the type of geological material that the extraction well penetrates, among other things.…”