Drilling Flashcards
What is the definition of pressure? What is the implication for casing?
Pressure is defined as force per unit of area.
The implication of this is that the thinner diameter pipes used as you drill deeper can sustain the higher pressures. This is the key driver of running the production pipe all the way to the bottom… This then makes the higher surface / intermediate casing largely redundant, other than letting the lower pipes exist.
What do you call the initial top level casing in a well. Typical dimensions?
Stove pipe or conductor
30” diameter and 1” wall thickness
What is a liner and what is the implication of a liner for the intermediate casing?
A liner is a bottom section in the well which hangs from the intermediate casing, rather than running all the way to the surface. The implication for the intermediate casing is that it then needs to be able to sustain higher pressures that would otherwise have been restricted to the smaller pipe, so higher wall thickness and corrosive proof intermediate casing becomes capable of being production casing.
5 key phases of a well?
Drill Log reservoir Case reservoir Cement Perforate
What is a round trip (tripping)
The process of taking the drill bit and pipe (drill string / casing string) out and putting it back down the hole again (maybe moving 2km of pipe in and out)
What is the function of the deadline?
Deadline is a static supply of wire that can be fed into the block line. As the wear and tear of dragging the traveling block up and down deteriorates the wire deadline lets you change the area where the wear and tear happens on the block line. The process of changing this is called slipping the line. Slip and cut refers to when you also remove “cut” some of the accumulated deteriorated line.
Simple purpose of well head and Christmas tree?
Well head, meets and supports (suspends) all of the well casing points, thinner cases run higher into the well head.
Christmas tree. terminates the production tubing and has a series of valves to capture the output. Nb the production runs through the well head into the Christmas tree.
What quantity of drilling fluid normally in use and in the drilling storage? What pressure is the mud pumped into the system at?
1500 barrels, several large teu containers?
2500-4000psi normally with at least one but often two redundant pumps as it is critical.
Three options for driving the drill?
- Top drive - rotates the drill string and thus the bit
- Mud motor, turbine on end of the string where mud pumping through the drill string turns the drill bit (like at the dentist)
- Kelly and rotary table (less used now)
4 functions of the drill string?
- Transports high pressure drilling fluid
- Provides weight on the bit (wob)
3, transmits rotary power - Controls deviation
Why is their weight on bit rather than on the string? How is weight achieved?
Weight on the whole drill pipe from the top can’t be supported from the top… It will lead to a helical pipe. Instead the weight is applied at the bottom with dense drill collars 3in wall thick collars. Each collar will be 10mt /30 ft long in vicinity of 60000lb.
Using the drill string you can control the amount if weight on the bit.
How do you drill “up” towards the surface! What do you need for this?
You would use hwdp heavy weight drill pipe which has more weight and provides more “push”, this requires that the pipe be stronger and resistant to both compression and tensile loads. If you need to drill multiple km “up” you may also use collars but they would be moved higher up the string to provide push not pull. You may also use aluminum pipe at the end which is lighter and easier to push up.
What is the function of a tool joint, where are they located?
Because drilling pipe is thin, the drill pipe can’t be joined / threaded itself. The tool joint is welded onto the drill pipe during production and is how the pipe is joined together. The tool joint needs to be threaded and unthreaded thousands of times.
How does drill string impact the casing?
The thickest part of the drill pipe is the tool joint. The joint is typically coated in something hard to make it long lasting such as tungsten carbide,
Thus requires that you allow for steel erosion in the casing as a rotating drill pipe will wear down the casing.
What are slips used for?
Slips are part of the rotary table, they hold the drill pipe in place whilst the top drive is disconnected, raised up and the next stand of pipe attached to the top drive. It is then connected to the last piece of casing (held in the slips), the top drive is taken further up (to release the slips) and drilling continues.
