5.2.1. Production well design and development
The design of proper efficiency of the two well production has been
required to yield maximized, proper the construction of selecting the
materials, casing diameter of the two well and depth, and the interval
screened. Lower maintenance and operation costs are the main factors of
properly-designed of wells (Naggar, 2005). The selected diameter of the
well 160 mm and it has provided the percentage desired of the slotted
(open) area in the screen (14% to 19%) and it is ensured the pumped
groundwater velocity near the screen for minimizing the drawdown and
losses of well (Fig. 4(e)) and (Fig. 3(c)). It also prevents the
migration of sand and clay- or silt-sized particles because of using the
150mm piping (Smith, 1966). The grain size of the penetrated beds and
selected slot sizes has depended on the appropriate screen slot size
depends. These particles are prevented at least 90% of the aquifer
substances from entering the well at the time of pumping. The filter or
artificial gravel pack (clean, uniform-sized, well-rounded grains) must
be used around the casing and screen of the well (Naggar, 2005). Then it
is sealed to the above so that clogging the screen can prevent the fine
material. The design of well screen has affected by well productivity
and efficiency (Zakaria et al., 2015). The features of design have been
included screen diameter, length, slot size, and material. The amount of
water entering the pipes maximized by the proper screen designs and
minimized by entering sediments entering the screen (Naggar, 2005). The
screen is placed where permeable layers has been found. In the two well
4th aquifer has considered as the confined aquifer and
high thickness and homogeneous well of the water-bearing zone. The main
process of pipe installation and water production has shown in Fig.
4(a-f) and Fig. 5.
In this study, it is found that design has been included 200mm dia, 200
×150mm dia reducing socket, 150mm blind pipe, 150mm strainer which is 30
slot and 150mm bail plug. The total fixture length is 226.37 meters of
the well 2nd whereas the total fixture length is
232.45m well 4th. For well No. 4, at first bail plug
jointed by using glue and screw with 150mm class E blind pipes 6m and
lower to borehole than strainer has been started from 225.79 to 197.56m,
in total 10 pieces of 150mm dia class E pipes with the length of 3m.
Total strainer length of 28.20m. Blind pipes as well casing started from
197.56 to 57.98m, in total 24 pieces of 150mm dia class E pipes (Fig.
4(f)) with the length of 6m. For well No. 2, at first bail plug jointed
by using glue and screw with 150mm class E blind pipes 6 meters and
lower to borehole than strainer started from 220 to 191.77 meters, in
total 10 pieces of 150mm (Fig. 4(b)) dia class E pipes with the length
of 3m with 30 slots. Total strainer length is 28.20m. Blind pipes as
well casing started from 191.77 to 75.32m, in total 20 pieces of 150mm
dia class E pipes with the length of 6m. The development of two well has
enhanced aquifer material’s permeability by using the chemical
calculation and gravel checking. This calculation increases the
production of well yield and efficiency (Naggar, 2005; Zakaria et al.,
2015). When slotted openings are larger, the water velocity and
frictional resistance are smaller. Drilling methods and features of the
surroundings beds (aquifer materials) has been monitored by the
development techniques of well.