1.0.1 This standard is formulated in order to unify the technical requirements for the design and construction of water-supply well engineering.
1.0.2 This standard is applicable to the design, construction and acceptance of well engineering for domestic water and industrial production water supply.
1.0.3 The design and construction of water-supply well shall be carried out after obtaining the hydrogeological information at exploration phase which is specified in the current national standard "Specifications for Hydrological and Geological Exploration of Water Supply" (GBJ 27). If the above-mentioned information can't meet the design or construction requirements of water-supply well, equivalent hydrogeological exploration shall be conducted, or the design or construction shall be carried out according to exploration - production well. The exploration - production well shall comply with the requirements of both "Specifications for Hydrological and Geological Survey of Water Supply" (GBJ 27) and this standard.
1.0.4 The material for water-supply well shall be provided with product certificate; in case no product certificate is provided, the material shall not be used before passing the inspection test. Pollution-free and intoxic materials shall be adopted for domestic water-supply well and its relevant materials.
1.0.5 The water-supply well must be subject to formal acceptance before being put into service.
1.0.6 The design, construction and acceptance of water-supply well engineering shall not only comply with the requirements stipulated in this standard, but also meet those in the relevant current compulsory standards of the nation.
2 Terms and Symbols
2.1 Terms
2.1.1 Exploration - production well
A water-supply well which is available for water supply exploration to obtain hydrogeological information.
2.1.2 Drilling technology
A generic term for well completion during the water-supply well construction.
2.1.3 Well measurement
A procedure to measure well depth and well diameter.
2.1.4 Well completion technology
A generic term for well measurement, slurry replacement, well casing erection, gravel pack, well seals and cleanup, pumping test, water sampling, etc.
2.1.5 Well structure
A generic term for well diameter, well section and well depth.
2.1.6 Well diameter
Diameter of well cross-section.
2.1.7 Top-of-well diameter
Diameter of well cross-section on the top.
2.1.8 Bottom-of-well diameter
Diameter of well cross-section at the bottom.
2.1.9 Diameter of pump installation section of well
Diameter of well section for installing pumping equipment.
2.1.10 Diameter of water yielding section of well
Diameter of well section for taking underground water.
2.1.11 Casing pipe
A blind pipe for supporting and sealing casing.
2.1.12 Well casing
A generic term for casing pipe, screen pipe and blank casing slump.
2.1.13 Blank casing slump
A blind pipe whose bottom is used for depositing sand grains and sediments inside well.
2.1.14 Flushing media
A substance for carrying rock cutting, cleaning well bottom, cooling and lubricating drilling tool and protecting casing during the drilling.
2.1.15 Screen assembly
A device for water screening, sand blocking and casing protection, which is located at water yielding section.
2.1.16 Cage-type screen
A screen assembly with one layer of entrance face.
2.1.17 Screen pipe
A cage-type pipe of wire-wound screen and gravel-packed screen; where used individually, it is also known as screen assembly.
2.1.18 Gravel pack
Round grains of certain size, which are filled into the annular gap between screen pipe and casing.
2.1.19 Gravel-packed screen
A screen assembly for filling certain size of gravel pack around the outside of screen pipe.
2.1.20 Wire-wound screen
A screen assembly winding certain type of wire and with certain porosity.
2.1.21 Effective porosity of screened well
The actual porosity of screen pipe which is installed at the water yielding section of well.
2.1.22 Well deflection
The horizontal displacement where the actual axes of well depth deflects from the vertical line.
2.1.23 Seals
A technology where different materials are used around the well casing to prevent water body from infiltration.
2.1.24 Maximum allowable entrancevelocity through well-wall
The maximum allowable entrancevelocity for underground water to enter inside well from water-bearing layer.
2.1.25 Maximum allowable entrancevelocity through well screens
The maximum allowable entrancevelocity for underground water to enter the screen pipe.
2.2 Symbols
Dg——Outside diameter of screen pipe
Dk——Diameter of water yielding section of well
K——Permeability coefficient of water-bearing layer
L——Length of screen assembly or gravel-packed section
N——Effective porosity of screened well
Q——Design water yield
Qg——Entrance capacity of screen pipe
Vg——Maximum allowable entrancevelocity through well screens
Vj——Maximum allowable entrancevelocity through well-wall
3 Design Requirements
3.1 General Requirements
3.1.1 In the design of water-supply well, the following main items shall be defined:
1 Water usage, water demand (or well number) and water quality requirement;
2 Scope of proposed well area;
3 Design idea and construction schedule of water supply;
4 User's other requirements;
3.1.2 Before the design of water-supply well, information related to the well construction site shall be collected and site survey shall be carried out.
3.1.3 The design of water-supply well shall be based on the water demand, water quality requirement as well as the hydrogeologic condition of well construction site, and should meet the following requirements:
1 The site is close to main water consumption area;
2 The well cluster has reasonable layout, and the average interference coefficient between wells should be 25%~30%;
3 The well location and buildings or structures shall keep sufficient safety distance.
3.1.4 In the design of well cluster, spare water-supply well shall be reserved. The quantity of spare water-supply well should be arranged according to 10%~20% of the measured water volume, and there shall be at least one well.
3.1.5 In the design of well cluster, long-term observation network shall be established according to the hydrogeologic condition, water demand and water quality requirement at the well construction site so as to monitor the underground water yielding dynamic. The layout of long-term observation network for underground water and the design of long-term observation port shall meet the requirements of the current national standard "Specifications for Hydrological and Geological Survey of Water Supply" (GBJ 27).
3.1.6 The design of water-supply well structure should include the following items:
1 Well structure;
2 Well casing configuration and pipe material selection;
3 Gravel-packed position and gravel pack size;
4 Seals position and material;
5 Ancillary facilities of well.
3.1.7 The design of well diameter shall include the following items:
1 Top-of-well diameter;
2 Quantity and reducer of well sections;
3 Diameter of pump installation section of well;
4 Diameter of water yielding section of well;
5 Bottom-of-well diameter.
3.1.8 Backfilling or other solutions shall be proposed for water-supply well which fails to meet the design requirements or is not applicable.
