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to bottom, or making a round trip; and (4) running and cementing casing, the large-
diameter steel pipe that crew members put into the hole at various, predetermined
intervals. Usually, operating companies hire a special casing crew to run the casing
and they engage the services of a cementing company to place the cement around
the casing. Nevertheless, the rig crew usually assists in running casing and cementing it
in the well.

DRILLING THE SURFACE HOLE

To begin, assume the rig crew is ready to begin drilling the first part of the hole. In
our case, let's suppose that the rathole crew prepared the initial 50 feet (15 metres) of
hole. They drilled and lined it with conductor pipe as described in the section on
preparing the drilling site. The diameter of the conductor pipe varies, and its
diameter depends on many factors, but it is usually large. In our case, let's assume it is
20 inches (508 millimetres). Therefore, the first bit the crew runs into the conductor pipe
will have to be smaller than 20 inches. In this case, let's say they use a 172- inch (444.5-
millimetre) bit.
They make up this bit on the end of the first drill collar, and they lower both bit
and drill collar into the conductor hole. They make up enough collars and drill pipe to
lower the bit to bottom. On a rig using a rotary table and kelly, the driller then picks
up the kelly out of the rathole where it has been waiting. Crew members then stab and
make up the kelly onto the topmost joint of drill pipe sticking up out of the rotary
table. The slips suspend this joint (and the entire drill string) in the rotary table.
With the kelly made up, the driller starts the mud pump, lowers the kelly drive
bushing to engage the master bushing. The driller actuates the rotary table to begin
rotating the drill stem and bit. The driller gradually releases the drawworks brake, and
the rotating
Normal Drilling Operations
Bit touches bottom and begins making hole. The sequence with a top drive is
much the same as with a rotary table and kelly. The crew stabs and makes up the last joint
of drill pipe onto the drive stem of the top drive. The driller then starts the motor in the top
drive to rotate the string and bit, begins circulating mud, and lowers the assembly to
bottom.
With both a top drive and a rotary table system, using an instrument called the
"weight indicator," the driller monitors the amount of weight put on the bit by the drill
collars. After the bit drills about 30 feet (9 metres), which is about the length of a joint of
drill pipe, crew members must add a new joint of pipe to drill deeper. On rigs with a
rotary table, crew members say that the "kelly is drilled down," meaning that the bit
has made enough hole so that the top of the kelly is very near the kelly drive bushing.
With the kelly (or the joint of drill pipe on top-drive rigs) drilled down, the
driller stops rotating, picks up (hoists) the drill string, and stops the mud pump. The
floorhands are ready to make a connection – that is, they are ready to add (connect) a

new joint of drill pipe to the drill string so that the bit can drill another 30 feet or so.

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