Tripping In
Tripping in means to run the drill string back into the borehole after the drill string has been completely removed, or tripped out (discussed below), something that may be done for a number of reasons.
After the well has been cased and cemented, the drill bit needs to be changed to a smaller diameter that fits within the new casing. To change the bit, the entire drill string needs to be out of the hole all the way until the bit is able to be swapped. Given the bit is the first part of the drill string in, it is the last thing to come out of the borehole. Once replaced, the new bit is tripped in until it hits the wiper plug on top of the float collar (see the cementing section for details). This and the cement in the shoe track is drilled through by the bitWhen the new bit makes it through everything at the bottom of the casing and hits new rock, drilling operations continue as before, only with a smaller borehole.
Tripping Out
Depending on the well design, drilling will halt once the drill bit has reached the maximum depth of a given casing set point. In order to drill the next section of hole, which will have a smaller casing, the drill string must be pulled out so that the casing can be run and cemented in place.
The drill string is also removed from the hole for a variety of other reasons, including a worn-out drill bit, a desire to use wireline tools to evaluate a well, to core a borehole, and the need to “fish” lost pieces of equipment from the hole.
The process of removing the entire drill string from a well is called tripping out, and can be quite involved. Depending on the size of the rig, the drillstring is removed in stands, which may consist of two to four pipe lengths screwed together. This makes the
When a stand of pipe is clear of the hole, drillers place slips around the top of the next stand in the master bushing. These slips use friction to hold up the part of the drill string that is still in the hole.
After the slips are in place, the stand is unscrewed from the drill string. If the same drilling pipes are going to be used again, they are stored temporarily in the monkey board. This rack holds the top ends of the pipes steady in a rack, which eliminates the need to lower them to the pipe rack. The derrick hand is responsible for standing on the monkey board and guiding the 100 foot long pipe segments into the rack.
Images: “Looking Up” by Michael Black; “Slips” by Michael Black; “Connection” by Michael Black; “Monkey Board Pipes” by Michael Black