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.