WELL CONSTRUCTION AND WELL DRILLING BASICS AND TUTORIALS

WELL CONSTRUCTION AND WELL DRILLING BASIC INFORMATION
How To Construct and Drill Wells? The Different Well Drilling Methods


Well Construction
Geologic conditions dictate two general types of well construction. A well that taps an aquifer of water-bearing sand is cased through the overburden and screened in the water-bearing sand as shown in Figure 4-1 a (Johnson, 1975).

A well that taps an aquifer of consolidated rock consists

Well Drilling.
There are numerous methods for drilling the well. A few of these are highlighted
here.

• Cable-tool percussion:
The drilling operation is carried out by lifting and dropping a heavy string of drilling tools. The reciprocating action of the drilling tools mixes the crushed or loosened particles with water to form a slurry that is removed by a sand pump or bailer.

• Jet drilling:
The drill tools for the jet-percussion method consist of a chisel-shaped bit attached to the lower end of a string of pipe. Water is pumped through the drill bit and flows upward in the annular space around the drill bit carrying the cuttings to the surface.

• Hollow-rod or hydraulic percussion:
This method is similar to jet drilling except the water is pumped down through the annular space, and the cuttings are carried up through the pipe by the reciprocating motion and a set of valves that keeps the water from flowing downward.

• Rotary drilling:
The borehole is cut by a rotating bit. The cuttings are removed by drilling fluid that passes down the drill pipe system and out through the nozzles of the bit.

When the fluid reaches the surface, it is pumped to a pit where the bulk of the cuttings settle out. The drilling fluid is then reused.

• Reverse circulation rotary drilling (RCR): The flow of drilling fluid is reversed from that used in conventional drilling. This is a common method for drilling community wells. This method is favored when completion of the well is to be by artificial gravel packing.

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