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Technical Memorandum 005-7 - Monitoring Sand Content: The Rossum Tester
Technical Memorandum 005-7 - Monitoring Sand Content: The Rossum Tester Imprimir
Lunes, 07 de Noviembre de 2011 17:31

 

 

Introduction

The bane of many well operators is sand that is produced during pumping. While it is not uncommon for a small quantity of sand to be discharged during start up, chronic sand production will usually accelerate the normal wear of impellers and other pump parts and clogs meters and valves. If left uncontrolled, sanding also increases the frequency of equipment maintenance and replacements, and causes nuisance problems for pipelines and water storage facilities. Whether the cause for sand production is design related or the result of corrosion, it is important to monitor the quantity of sand that is discharged from the well on a regular schedule.

 

Sand production is a key criterion of new wells and should be carefully monitored when the well is developed and pump tested. During the early stage of well development, the quantity of sand discharged often exceeds 50 milligrams per liter (mg/l). Such concentrations are expected and even desirable. Precise measurements of sand content during this phase of well completion can be made with an Imhoff cone or other suitable device. However, in the later stage of well development and during performance testing, accurate sand content measurements are needed. In fact, most operators cite a specific criterion in well construction specifications that defines the upper limit of sand production that is acceptable. Generally, this can range from 15 mg/L to less than 1 mg/L.

During a well’s life, sand production may increase for various reasons. For example, corrosion of casing and/or screen may allow for passage of sand into the well. Or, a poorly selected gravel pack might be unable to filter fine sand from passing through the well screen. In either case, if routine sand monitoring were conducted, the change in sand content could signal the problem to the well owner.

For monitoring sand content during a pump test or at regular intervals during a well’s life, American Water Works Association (AWWA) Standard A-100 suggests the use of the Rossum Sand Tester (RST). An RST is easy to operate, low in cost, reliable, and widely used in the water industry.

ENVIADO POR RAÚL CAMPILLO U., HIDROGEÓLOGO

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