Page 85 - 4925

With the elevators vertical, the crew stabs the new joint into the drill string
suspended in the rotary table. The driller uses a built-in wrench in the top drive to spin
up the joint and torque it to final tightness. Or, if desired, the crew can use tongs to
buck up the joint. The driller then starts the mud pump, begins rotating the string and
bit, and lowers the bit to bottom to continue drilling.
At a predetermined depth, perhaps as shallow as a few hundred feet (metres) to as
deep as two or three thousand feet (metres), drilling stops. Drilling stops because crew
members drill this first part of the hole – the surface hole – only deep enough to get
past soft, sticky formations, gravel beds, freshwater-bearing formations, and the like
that lie relatively near the surface. At this point, crew members remove {trip out) the
drill string and bit from the hole. They trip out the drill string and bit so that they can
run casing into the hole. Once they cement the casing in place, the casing protects the
formations that lie behind it and prevents fluids in the formations from migrating
from one formation to another. For example, a saltwater zone could contaminate a
freshwater zone if the operator did not case and cement the hole. The casing also
protects these shallow zones from being contaminated by the drilling mud used to drill
the hole below the casing.

TRIPPING OUT WITH A KELLY SYSTEM

To trip out (to remove the drill stem from the hole) on a rig with a kelly system,
crew members set the slips around the drill stem, break out the kelly, and set it, the
kelly drive bushing, and the swivel back in the rathole. Still attached to the bottom
of the hook are the elevators. The driller lowers the traveling block and elevators
down to the point where crew members can latch the elevators onto the pipe. The
driller raises the traveling block, thus raising the elevators and pipe, and the floor hands
remove the slips.

Meanwhile, the derrickman, using a safety harness and climbing device,
has climbed up the mast or derrick to the monkeyboard. The monkeyboard is a
small working platform on which the derrickman handles the top of the pipe. As
the driller raises the pipe to the derrickman's level, the derrickman pulls the top of
the pipe back into the fingerboard.
The fingerboard, as the name implies, has several metal projections (fingers)
that stick out to form slots into which the derrickman places the top of the
pipe. When the floorhands move the pipe off to one side of the rig floor and set it
down the derrickman unlatches the elevators and prepares to receive the next stand
of pipe. The floorhands do not break out (disconnect) every single joint of drill pipe
or drill collar one at a time. Instead, they usually pull two or three joints at a time.
So, although they put pipe into the hole one joint at a time when drilling, they
pull it out two or three joints at a time.

84