oil field pipe based well screen/johnson well screen

• Pipe based well screen

Pipe based screens are used in water wells in many parts of the world and are common in oil field work because of their strength and durability in non-vertical borehole applications. the assembly for this screen is made by perforating a base peple and then mounting a continuous slot screen over it via one of three methods: 1) winding trapezoid-shaped wire directly onto a pipe(wrap-on pipe); 2) winding wire over longitudinal rods mounted around a pipe's circumference(pipe base); or 3) slipping a separate continuous slot well screen jacket over a pipe(screen jacket). winding wire over longitudinal rods is superior to the wrap-on pipe design because the rods hold the wire away from the pipe surface, blocking fewer of the base-pipe openings.

The pipe based screen has two sets of openings, the outer continuous slot and the holes drilled in the pipe base. The open area of the pipe base generally is less than that of the outer screen open area, and the inner pipe has a maximum open area of *0%. Hydraulic performance of the assembly depends on the open area in the pipe base, which usually is made of steel and has an outer screen made of stainless steel. This bimetal contact typically supports some electrolytic action and causes corrosion of the steel pipe. One way to prevent corrosion is to use pipe and screen made of the same metal- the cost might be somewhat higher, but the product is more durable.