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Johnson well screen

2017-08-16 By Lisa

Johnson well screen is also called wedge wire screen or continuous slotscreen,which consists of wedge-shape profile wire and the longitudinal supportrods. each intersecting point of these wires is fusion welded.so water well screen has sturdy constriction and good mechanical property. And the wedge-shape section plane can avoid blockage,and make sure of the unimpeded water.the consecutive slot have more open area,and water well screen can reduce the speed of the water entering to aviod the sand entering the screen under the great pressure,so wedge wire water well screen pipes can filter sand better. Meanwhile, the slot can change according to the real condition of the earth.

Johnson well screen

Strength and Durability of the Johnson Well Screen

Regardless of construction method,Johnson well screen have some common requirements. Strength must be adequate to withstand not only the stresses of installation, but also other forces which may be applied during well completion, development and use. The forces of installation which tend to pull the casing and screen apart must be exceeded by the tensile strength of the material. The resistance of the casing to collapse must be greater than the external hydrostatic forces calculated.
Radial stresses of the wall of a small diameter hole in a consolidated formation are negligible. However, it is impossible to calculate the load on casings and screens in unconsolidated formations. Unknown are forces from formation sloughing, caving and subsidence, or the sudden downward movement of filter pack material. These stresses can rupture casings and screens.
Another requirement related to strength is durability. Small increases in the wall thickness of ordinary low carbon steel casings not only improve strength, but under most conditions, extend well life, from a corrosion standpoint, by a factor greater than the percentage thickness difference. Corrosive environments may require the use of special corrosion-resistant material.

Material of the Johnson Well Screen

By far most common Johnson well screen material is steel. Steel is easily formed into tubes, the ideal casing and screen configuration. When exposed to the atmosphere, water or soils, steel builds up a protective oxide coating which assures long life under mildly corrosive conditions. Under more extreme conditions, steels with special chemistries or alloys, such as the stainless steel grades, are available for greater life or permanent protection. Steel possesses the high yield and tensile strengths required for water well use. Of particular importance are the characteristics of elasticity and resiliency inherent in steel. Johnson well screen may be subjected to underground external forces after installation. Earthquakes or subterranean earth movements tend to displace them. Steel permits absorption of many forces with maintenance of structural integrity. Another important quality of steel is its weldability. This facilitates proper field installation.

Johnson well screen

Handling and Maintenance of the Johnson Well Screen

Ease of transport, handling and installation are important considerations. These not only influence cost but are also relevant to the selection of the type of casing and screen field connections. Johnson well screen should be designed to facilitate future rehabilitation including cleaning, incrustation removal, redevelopment and repair. Another consideration is the possibility of future well deepening. Casing and screen diameter as well as type and material selected are influenced by the parameters.
 

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