Slotted liners are made from tubulars by saw-cutting slot configurations
Slotted liner is a popular sand control screen in long horizontal completions and low productivity wells. Precision slotted liners are manufactured by CNC controlled slotting machines or laser machine. All slots are de-burred, cleaned and drift tested according to API standards. Base pipe are per API casing or tubing specification with diameters from 1.5 inch to 18 inch. Pipe lengths of any diameter are available.
Slot size including slot width and length is customized to suit customer’s requirement. For straight or keystone slots, minimum slot width is 0.012 inch and maximum slot width would be 0.25 inch.Slot widths are often referred to in terms of gauge. Slot or screen gauge is simply the width of the opening in inches multiplied by 1,000. For instance, a 12-gauge screen has openings of 0.012 in.
Slotted liner patterns
Three slot patterns are designed for different characteristics (shown below). Compared to staggered and straight slot patterns, gang slot pattern has superiorities over installation torque-loading capacity and substantially improves the liner’s resistance to lateral bucking and collapse pressures.
Staggered slots features:alternate slot evenly spaced around the circumference with offset.
Gang slots feature:multiple slots evenly spaced around circumference in a staggered pattern.
Straight slotted liner features:slot columns spaced evenly around the circumference without offset.
The length of the individual slots is measured on the inside diameter (ID) of the pipe. Usual practice dictates 1½-in. long slots for slot widths of 0.030 in. and under, 2-in. long slots for slot widths between 0.030 to 0.060 in., and 2½-in. long slots for slot widths of 0.060 in. and larger. Slot width tolerance is generally ± 0.003 in. for widths of 0.040 in. and wider and ± 0.002 in. for widths less than 0.040 in.
The primary advantage of a slotted liner over wire-wrapped screens is usually cost; however, small gauge, high-density slot patterns may cost as much as wire-wrapped screens. The disadvantages of the slotted liner are:
limited flow area (2 to 3%, creating a low tolerance to plugging)
minimum available slot size (approximately 0.012 in.).
Slot widths that are less than 0.020 in. and cut in standard carbon steel-pipe grades can rust and will either close or reconfigure the slot opening so that they do not function properly unless they are coated, protected, or stored indoors before use.
All slotted joints are deburred internally, cleaned and drift tested according to API standards. Every slot is visually inspected and cleaned of burr material. All threads and couplings are thoroughly cleaned and lubricated.
The size, grade and weight of the base-pipe are according to API casing or tubing specification.
|SLOT WIDTH||250μ to 18 mm||0,01” to 0,25”|
|SLOT LENGTH||38 – 50 – 63 – 76 mm||1,5” – 2” – 2,5” – 3”|
Slotted liners are suitable for gravel packed completions or stand-alone completion where grain size is large.