Advantages of casing drilling
1. Reduce the time of starting and drilling. It is about 5-10 times faster to replace the drill bit with a wire rope than with a conventional drill pipe.
2. Save on the purchase, transportation, inspection, maintenance and replacement costs related to drill pipes and drill collars;
3, because there is always a casing in the well-bore, there is no longer the pumping effect on the well-bore when the drill pipe is lowered, which improves the well control situation;
4. Eliminate the pumping effect and pressure pulsation caused by the lower drill pipe;
5. When the drill bit is lifted with a wire rope, the mud can be continuously circulated, which can prevent the accumulation of cuttings and reduce the occurrence of well surge;
6. Improved annulus return speed and well-bore cleaning. When the mud is pumped into the casing, its inner diameter is larger than that of the drill pipe, which reduces hydraulic loss, which can reduce the power of the drilling rig mud pump. When the mud returns from the annular space between the casing and the wall of the well, the area of the annulus is reduced, which increases the return speed and improves the carry-out of cuttings;
7. It can reduce the size of the rig, simplify the structure of the rig, and reduce the cost of the rig. The reasons are as follows:
(1) The improvement of hydraulic parameters has reduced the demand for drilling rig mud pump power.
(2) Can remove the second floor platform and the drill pipe box of the drill pipe.
(3) no longer use drill pipe,
(4) Casing drilling is based on a single casing, and it is no longer necessary to use a vertical root drilling method similar to two or three drill pipes, so the derrick height can be reduced and the weight of the base can be reduced. To build a single drilling rig, the structure and weight of the derrick and base are much simpler than those of a vertical drilling rig;
8. The rig is more portable and easy to move and operate. Both manual labor and expenses will be reduced.
2. Save on the purchase, transportation, inspection, maintenance and replacement costs related to drill pipes and drill collars;
3, because there is always a casing in the well-bore, there is no longer the pumping effect on the well-bore when the drill pipe is lowered, which improves the well control situation;
4. Eliminate the pumping effect and pressure pulsation caused by the lower drill pipe;
5. When the drill bit is lifted with a wire rope, the mud can be continuously circulated, which can prevent the accumulation of cuttings and reduce the occurrence of well surge;
6. Improved annulus return speed and well-bore cleaning. When the mud is pumped into the casing, its inner diameter is larger than that of the drill pipe, which reduces hydraulic loss, which can reduce the power of the drilling rig mud pump. When the mud returns from the annular space between the casing and the wall of the well, the area of the annulus is reduced, which increases the return speed and improves the carry-out of cuttings;
7. It can reduce the size of the rig, simplify the structure of the rig, and reduce the cost of the rig. The reasons are as follows:
(1) The improvement of hydraulic parameters has reduced the demand for drilling rig mud pump power.
(2) Can remove the second floor platform and the drill pipe box of the drill pipe.
(3) no longer use drill pipe,
(4) Casing drilling is based on a single casing, and it is no longer necessary to use a vertical root drilling method similar to two or three drill pipes, so the derrick height can be reduced and the weight of the base can be reduced. To build a single drilling rig, the structure and weight of the derrick and base are much simpler than those of a vertical drilling rig;
8. The rig is more portable and easy to move and operate. Both manual labor and expenses will be reduced.
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