CWD Well Construction & Casing Design 3

Question 1

What does a telescoping well design refer to, and when is it used?

Accepted Answer

A design using progressively smaller casing diameters at greater depths to manage unstable formations or reduce costs

Answer

A design with expanding diameter at depth to maximize yield in productive zones

Answer

A design using flexible casing sections that extend under hydraulic pressure

Answer

A design with multiple horizontal laterals extending from a central vertical borehole

Question 2

In which situation would steel casing be clearly preferred over thermoplastic (PVC) casing?

Accepted Answer

Wells deeper than 200 feet or where significant lateral earth loads are anticipated

Answer

Shallow wells in warm climates with mildly acidic groundwater

Answer

Residential wells in corrosive, high-chloride groundwater environments

Answer

Low-yield domestic wells in consolidated bedrock formations

Question 3

What is the primary purpose of a well screen installed at the base of a production well?

Accepted Answer

To allow water to enter the well while blocking aquifer sediment from entering

Answer

To filter bacteria and viruses from raw groundwater

Answer

To measure the velocity of groundwater flowing toward the well

Answer

To prevent galvanic corrosion between the casing and pump column

Question 4

According to well screen design criteria for naturally developed wells, the slot opening is typically sized to retain approximately what percentage of the aquifer sample by weight?

Accepted Answer

40%

Answer

20%

Answer

70%

Answer

90%

Question 5

What is the purpose of a casing vent on a completed water well?

Accepted Answer

To equalize pressure and prevent vacuum formation inside the casing during pumping

Answer

To allow periodic water quality sampling directly from within the casing

Answer

To introduce chlorine or other disinfectants into the well during shock treatment

Answer

To measure static and pumping water levels using a pressure transducer

Question 6

What is the function of an artificial gravel pack (formation stabilizer) installed around a well screen?

Accepted Answer

To create a highly permeable zone that prevents aquifer sand migration and improves specific capacity

Answer

To stabilize the drill bit during penetration of hard consolidated rock

Answer

To prevent surface contamination from migrating downward along the casing

Answer

To reduce drilling costs by minimizing the borehole diameter required

Question 7

What factor primarily determines the appropriate length of well screen to be installed in a production well?

Accepted Answer

The saturated thickness of the productive aquifer and the required well yield

Answer

The total drilled depth of the well

Answer

The type and schedule of casing material selected for the well

Answer

The vertical distance from the static water table to the pump intake setting depth