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Benefiting Mine Technology-Basic Drilling Skills That Should Be Deeply Understood
Release time:
2019-09-11
Author:
Source:
What is the reason for the resistance in drilling? How to deal with it?
The reasons for the resistance in the drilling are:(1) the well collapses after the completion of the drilling. (2) The well diameter is reduced due to poor mud performance, large water loss, thick mud cake and formation expansion. (3) The diameter of the drill bit was seriously worn out during the last trip, and the new drill bit was blocked. (4) The mud is not well circulated before tripping out, and the drilling cannot be carried out to the bottom. (5) Structural changes of drilling tools. If the large drilling tool is replaced or the diameter centralizer is enlarged, it is easy to encounter resistance when the drill bit type is replaced.
Treatment method: before tripping out, the mud must be circulated well, and the performance of the mud must be well treated. During tripping out, the mud must be well filled according to regulations. Can not be strong pressure, strong down. Before tripping, the type and size of the drill bit shall be checked in detail; if the size of the drilling tool changes, attention shall be paid to prevent blocking and sticking during tripping.
2. How to deal with brake failure during tripping?
First of all, the low-speed clutch should be strongly engaged to slow down the sliding speed. The internal and external fitters can quickly clamp the slips or the elevator, and the wellhead personnel can quickly leave the wellhead. Then remove the clutch of the main vehicle, close the high and low clutches at the same time when the rotating speed of the drilling machine slows down, and repair the brake system after controlling the drilling tools.
3. What is the reason for the twisting of the big rope when drilling? How to deal with it?
Reasons for rope twisting:(1) The newly replaced wire rope is not loose. (2) The drilling tool is seriously reversed during tripping in. (3) The hook pin is not opened.
Treatment:(1) Loosen the live rope head of the big rope and loosen the torsion of the wire rope. (2) In case of reverse resistance in the drill-down, the drill-down speed can be controlled to reduce the rotation or slow down the rotation. If the hook pin is not opened, the slip can be stuck and the pulley can be rotated by human.
4. Why do you want to open the hook pin when lifting and drilling?
Opening the hook pin during tripping is mainly to use the free direction of the drilling tool in the shaft to rotate flexibly, which is conducive to smooth tripping out; opening the hook pin during tripping is mainly to prevent the wire rope from twisting when the drill pipe is buckled, and at the same time, the operation of the trek and wellhead is convenient and flexible.
5. Why do you sometimes need to circulate mud during drilling?
1) The downhole has not been tripping in for a long time, or the mud has not been circulated well due to other reasons before the last trip, so as to prevent the mud performance from deteriorating and the pump cannot be started.
2) Collapse of downhole formation.
3) Slurry performance is deteriorated due to salt water, gypsum and other pollution.
4) There is slight leakage downhole.
5) The downhole situation is complicated, and the pump is often not started.
6) For complex deep wells or ultra-deep wells, or high-pressure oil and gas layers have been drilled, the mud shall be treated in sections.
If the mud is not circulated halfway, it will cause resistance to tripping, the pump will not be started after tripping, or the pump pressure is too high to leak the formation.
6. What is the reason why the pump cannot be started after drilling? What should I do?
Reasons why the pump cannot be started after drilling:
1) A large number of drilling tools are replaced during this time. There is dirt in the water hole of the drilling tool to block the water hole of the drill bit.
2) Something, such as lead oil brush, gloves and cotton yarn, fell out of the drilling tool during tripping.
3) During tripping, due to the collapse of the borehole wall, mud is seriously returned, and drill cuttings are brought into the drilling tools to block the water hole of the bit.
4) Ground pipelines or drilling tools are frozen in winter.
5) The mud cake on the well wall is thick and a large amount of rock debris is sandwiched, which will be squeezed into the drill bit to block the water hole during drilling.
6) The mud cake on the well wall is thick, which makes the bit mud bag and the mud cannot return. If there is a permeable layer at the lower part, it is easy to leak the formation.
Processing method:
If the pump cannot be started, first remove the ground factors (such as cock and gate not being opened); then deal with downhole problems, move the drilling tools at a large distance and start the pump slowly with a small displacement. If some drilling tools are not effective, start the pump slowly with a small displacement. If there is no effect, trip out as soon as possible to prevent downhole deterioration and drill sticking.
7. In the middle of drilling, the faucet or hose suddenly breaks down and cannot circulate mud. How should it be handled correctly?
During drilling, if the faucet leaks mud or the hose is broken, the 100-200m drilling tool shall be pulled out to the safe well section, and personnel shall be assigned to move the drilling tool while manpower shall be organized for emergency repair or replacement. If the downhole situation is complicated, the drilling tool shall be put into the technical casing; if the drilling tool is completely pulled out or put into the table casing without technical casing, it is not allowed to connect the drill pipe to put the repair faucet in the well repair faucet or replace the water pipe.
8. What is the reason for the decrease or no return of mud from the wellhead during drilling? How to deal with it?
First of all, check whether there is any problem with the ground manifold and pump. If the ground is normal, it means downhole leakage. The reasons are as follows:
1) There is permeable leakage layer or formation crack under the ground.
2) There are limestone karst caves.
3) The well collapse causes annular blockage, resulting in non-return of mud.
Processing method:
1) For permeability leakage, add leakage plugging agent while drilling and reduce the density appropriately.
2) In case of serious leakage, trip out immediately, fill mud with large displacement and take plugging measures.
3) In case of well collapse, the mud performance shall be improved, the drilling tools shall be greatly movable, and the drilling debris shall be slowly reamed to prevent drilling jam.
9. What is mud short circuit? What is the reason? How to judge?
Incomplete return of mud from the bit is called mud short circuit.
Causes of mud short circuit: ground high-pressure manifold (gate, flange, union and welded joint) is damaged or gate is inverted. Downhole drilling tools are damaged, tripping and broken.
The phenomenon of mud short circuit is that the pump pressure drops, the displacement remains unchanged, and the cuttings cannot be brought out, resulting in mud bounding and jumping of the drill bit, slowing down the drilling time, and sticking in serious cases.
10. What is the reason for the increase in pump pressure during drilling? How to deal with it correctly?
(1) The reason for the increase of pump pressure during drilling is that the well collapse causes the annulus to be blocked, the drilling tool water hole is blocked, the mud performance changes, the viscosity increases, and the fluidity deteriorates.
(2) If the well collapses, the mud shall be circulated with large displacement, and the rock cuttings at the bottom of the well shall be redrawn repeatedly, and the drilling tools shall be pulled out to check the drilling tools one by one if something falls in the drilling tools. Whether stones and sand are brought in when connecting a single tool in the drilling, the rubber of the water hose with rubber pieces and the rubber core of the VAL shall be dropped, causing water hole plugging. If the performance deterioration, the drilling, the drilling shall be stopped.
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