Analysis of common drilling problems
What are the phenomena of spills? What happened?
Overflow:
(b) Speed of drilling and even emptiness, and reduction of circulation pressure;
Increased up-to-exit flow of well-drilling fluids and increased surface of drilling tanks;
There are increased oil, bubbles or salinity in the well-drilling fluids, with changes in performance.
(a) When drilling begins, the amount of fluid that is injected into the well is less than the amount of the concrete volume from which the drilling is launched, and when the drilling is drilled, the amount of fluid that is returned to the well is greater than the amount of the concrete volume from which the drilling is drilled;
When a well is empty, it cannot be filled with well fluids or there is a continuous spill, and when it is drilled, it is drilled back or back from within the rigs, with a well surge in serious cases.
Reasons for spills:
Poor mastery of bottom pressure and low density of design well fluids;
(b) Decline of the liquid surface of the well due to drilling or a well leak;
(b) Reduction in the density of well-drilling fluids due to oil and gas immersion or other causes;
Drillings generate spills.
2. Why close wells quickly after spills?
Response: Control of wellheads can put well control at the initiative and contribute to the achievement of safe wells;
(b) To prevent the continued entry of the bottom fluid into the well;
(b) The maintenance of more well-drilled fluids in wells and the reduction of the pressure on the pits and the pressurized wells;
Bottom pressure and pressure well fluid density can be determined more accurately.
What’s the content of the well-controlled “four-sevens”?
Response:
(1) Spills during drilling
Signals are sent: when the sentry detects a spill, he immediately informs the Director-General, who sends a flute signal (usually not less than 30 seconds) and the duty officer is immediately in charge of the overall command.
Stop drilling into the S.D. Dripping signal while quickly removing the spin-off clutch and stopping the drill. Get the rigs up, pull the pump first, pull the one, use the two or three. Night electricians turn on the searchlights and then quickly turn off the other power sources of the dehydration control table.
(c) The rigs of the rigs, which were drilled on the rigs, so that the first of the drills under the poles was exposed to a half metre or so on the side of the wheel, and the internal and external pliers were placed on a hanger (the rigs should not have been placed on the card before closing the wells).
Open the 3# tablet valve (opening 1 # valve in the winter) – The siters quickly open the 3 # valve (opening 1 # valve in the winter) and, when it opens, report to the commander (or liaison officer) with a clear sign that the gate has been opened (the tablet valve must be fully turned on, closed, shut down, same).
Close the wells — the Deputy Division is quickly located in front of the remote control table, on standby to close the wells and perform the following three inspections.
a. Is the power switch in an automatic position?
b. Is the pressure normal?
c. Are the gates and handles in normal condition?
When instructed to close the wells, the wells are closed quickly and the rings are closed and the locks are closed in half. At this point, the internal and external pliers should observe whether the wellheads are closed (the handles have a time of not less than 15 seconds).
Artificial flow valves – When it is confirmed that the well sealer has been closed, the conductor gives the site worker a joint flow transfer order. When the site works on the arthropod valves, it is observed that the wellheads are at the maximum permissible level and at the lowest level, the pressure remains below the maximum permissible level and 15 # flat-wall valves are closed. The pressure is maintained when the pressure reaches the maximum permitted level of the well-turning pressurized, and is released from the vents (three well-heads, not 3 # gates, recovery of drilling fluids or ejection only).
The following information is taken when the pressure is stable and the pressure in the well is balanced.
a. Pressure on wells to shut-off
b. Incremental well-drilling
c. Closure of the wells tube pressure
After completing the procedures for closing the wells:
1) Reporting to superiors:
a. Three data for spills (excesses, presses, presses).
b. Underground condition (well-body structure, drilling position).
c. The status of spraying equipment.
d. Increased condition of equipment.
e. Re-drilling fluids, increased material reserves.
f. Security facilities (fire, gas).
2) The following should be noted:
a. No discharge shall be released after the well has been closed, and the discharge shall be transported through a throttle to prevent the drilling of the head eye.
b. To observe the pressure at any time and the change of the presse, and if the pressure rises, apply to the pressure of the tube, with the appropriate discharge from the current valve, and to maintain the pressure at a pressure greater than 1 MPa at the close well.
3) The operational requirements for the transition from the silo to the silo state are:
a. Slowly pump, rapidly open the 15 # tablet valve and maintain the pressure of the silo by regulating the 17 # throttle.
b. When the charge amount reaches the pressure-well charge, the pressure-well charge is maintained and the throttle is regulated on the basis of the pipe pressure values specified by the unit of construction of the pressure-well.
The alarm was lifted – when the pressure was set at zero after the pressure of the well, a long, rhythmic, short signal was sent, the site worker opened the 15# valve, opened the 17# throttle 3-5 circle, and made a two-armed outreach position to the commander, indicating that the pressure was no longer in place, and the commander informed the Deputy Director to drill for the opening of the well, and the division was able to continue its operations after it was confirmed that the sealer had been opened. The site workers open the gates in a normal process. After receiving the signal, each guard continues to operate back to his post. Summary of the presentations by the staff on duty on shift.
(ii) Spills of drilling
the article in the same paragraph (1).
Stop drilling, which should be pushed quickly into the rig box, when the rig has just been pulled or unloaded, and the hanger should open the hanger, the driver’s rig, and the well-builder should go down the rig after the cruiser has crossed the beam. The rigs shall be placed on the wheel immediately during the lifting.
The recovery valve – The internal and external pliers must be fitted when the repressure valve is open (when the spray is high, the revolving valve must be connected first, and then the revolving valve must be closed, and then the repressure must be returned. ) Tighten, strung, drilled, and the card left the turnboard area 0.1 to 0.3, pending the closure of the well.
Entry data – Admission:
a. Condom pressure
b. Spills
c. Determines the pressure of the main tube at the level of the main well (the relay drill, which is held at the minimum possible charge at the level of the well, and when the pressure is slightly greater than the pressure of the well (large 0.5 ~ 0.7 MPa), the pressure of the tube at the level of the well minus the added value of the pressure).
(3) When the drill starts and goes
the article in the same paragraph (1).
Stop operations.
The rigs with the rigs attached to the rigs are removed from the safe truck, the drills are brought down into the wells and the pressure valves are returned (when the blow-out is large, the valves must be attached first, then the valves must be closed, the valves returned and the valves opened). (b) Lifting of the crane to make the joint slightly lower than the well-sealed gate.
In the same (2), there is no need for a tube pressure because of the small number of drilling rigs.
(4) When empty wells
and (1)
, the clause in (3).
The wells were designed to control the wellheads and did not require the rigs to be taken, when the drilling companies were in charge of the wells control and management officers.
(The wells must comply with the no-arrival regulations, i.e., drills are completed, drills are replaced, and other operations, such as inspection, are allowed down to the edge of a set of shoes).
What’s the plan before you drill the gas?
Answer: (1) Technical turn-over to the entire team of workers in the areas of engineering, geology, drilling fluids and well control equipment.
(2) The liquid density and other performance of the drilling well meets the design requirements and there are sufficient liquid stressors and processors for the drilling well.
(3) The well-controlled equipment, specialized tools, fire-fighting equipment, circuit systems are complete and complete.
(4) Investigation and follow-up of the nearby water well stoppages and the construction of the adjacent wells to open the oil and gas layers.
(5) Implementation of a system of duty stations and staff officers for the clearance of wells.
(6) The entire team of staff shall carry out the class spray exercise and meet the required requirements for the exercise.
Five, what’s a well control? What’s a well-controlled five at a time?
A: A well control means the balancing of the pressure of the subsurface with the pressure of the well ‘ s liquid column to prevent the formation of the stratosphere into the well.
The five tasks to be performed by the Well Team are:
(c) Conduct technical bottom-up and strictly implement design and technical measures. There is sufficient reserves of re-drilling fluids, enhanced materials and drilling liquid processors, and the density of drilling fluids at the start of the drilling is the design maximum.
They are filled with well fluids on a continuous basis, reducing the amount of time that they have to be empty, and they are used to observe wellheads and to drill well fluids.
Daily inspections of the implementation of water well stoppages and depressures.
Keep the borehole open so that the pistons can be drilled.
The wells with shallow layers of gas are to be drilled with a slurry, open the atmosphere without interruption, and recycled after normal observation before continuing to drill in single root.
Six. What’s a soft well? How do we get to the soft well?
Response: When a spill is detected, the mains are turned on, then the wells are shut down, and then the method of closing the joints is called the softs wells.
7. What should be the focus of the manual lock-and-string device using the bolt-protector?
Answer: (1) The manual locking device can only be used to close the gate and cannot open it.
(2) To open the lock, the manual locking device must be unlocked and re-locked, and the lock must be opened by hydraulic pressure.
8. Why would the manual tablet valves rotate around one quarter to one half after the end?
Response: Accomplishments caused by the loss of a plume through the close-off of a hand-held tablet valve, which is in a condition of floating. Therefore, one quarter-1/2 laps are to be rotated after the end.
What’s a drill well? What’s an engineer’s law well?
A: Shi-based pressure wells are used to recycle the liquid from the original density wells after a spill has occurred, to discharge the spills, to increase the drilling of the wells, and to complete the pressure wells by two circulation weeks. This method is often applied in the event of the late supply of remote wells and stressors.
Engineers also referred to a cycling method, which quickly closed the well after the spill occurred, increased the drilling of well fluids based on calculated subsurface pressure and completed the pressure wells within a cycle week with enhanced drilling fluid.
10. How to determine the fluid density of drilling wells?
Response: The pressure factor for the top layer of the exposed well section should be based on a 0.05 – 0.10 g/cm3 for the oil layer and 0.07 – 0.15 g/cm3 for the gas layer.
11. What are the hazards to drilling wells arising from the viscosity, excessive cutting or lowness of drilling fluids?
A: Too sticky, too big.
(i) The difficulty of pumping, the high pressure of the pump, the high stress, the high stress, and the low pressure, the low pressure, the low pressure, the low pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the low pressure, the low pressure, the high pressure, the low pressure, the low pressure, the low pressure, the low pressure, the low pressure, the high pressure, the low pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the high pressure, the low pressure, the low pressure, the low, the low, the low, the low, the low.
(ii) Reduced drilling speed;
(3) Large cyclic pressure and high total pump pressure, which is detrimental to the drilling of the preferred parameter;
(4) Easy to drill with mud, resulting in a sling well;
(5) Vulnerability to violence; (b) Retaliation difficulties;
(vi) Debrusts and sands are not easily removed to affect the solid control effect, resulting in wear and tear of equipment and drilling equipment;
(7) The formation of thick mudcakes (sander cakes) in the wellhead wall makes drilling difficult and can easily occur with sticky cards.
(8) Drilling fluids are difficult to maintain and difficult to handle.
Magnificent, too low.
(1) Poor carrying and suspension capacity and poor well-washing effect, which can lead to heavy crystals and the sedimentation of drilling debris;
(2) Brushing of well walls, resulting in their defoliation;
(3) Leaking layers are prone to leakage.
12. How to adjust the viscosity of drilling fluids?
Answer: (1) Poor carrying and suspension capacity and poor well-washing effect, which can cause heavy crystals and the sedimentation of drilling debris to cause the drilling of diamonds;
a. The removal of soil by soil or water and the lifting of soil cover;
b. Add dispersants to increase clay dispersion;
c. Adding high-molecular adhesives;
d. Use of positive electrogel to improve viscosity and cut;
(2) The reduction of the fluid viscosity of drilling wells is achieved by:
a. Clearing of clay-solid phase using solid control equipment;
b. Dilution with water or low concentration of medicine;
c. Diluting with organic diluent;
d. Dissolved condensation, salt resistance, dilution and glucose treatment for increased viscosity caused by chemical contamination.
What are the factors affecting the LFS for drilling? How to control the fluid filtering of wells?
A: Factors affecting the silencing vectors of wells include the penetration rate of filter cakes, pressure differentials, filtration viscosity, leaching time, temperature, chemical contamination and substrate permeability. The most important of these is the permeability of the filter. Enriched, less permeable filtration is key to control of the filtration vector.
Method of controlling the filter vector:
(1) The use of pellets and hydrated membranes to form compacted filtries;
(2) Add a suitable amount of dispersants to increase the level of electro-electricity, hydrosis and dispersion of clay;
(3) Add diluents and glucose protection of fine clay particles to prevent their aggregation, thus contributing to greater clay dispersion;
(4) Add some very fine gel particles to plug in the cracks and reduce the permeability of the filtries;
(5) Add organic high molecular leachate and increase leachate viscosity, resulting in increased leaching resistance.
14. What are the hazards to drilling wells arising from over-drilling? Is the filter as low as possible? Why?
Response: The situation below wells can be complicated when well-drilled fluids are overloaded and the filters lack the ability to contain the collapse, such as the possibility of collapse and indentation in the water-sensitive mud section. High solid phase drilling fluids are too thick because of too large a filtration vector, resulting in a condensation of the borehole, a lack of open drilling and an impact on the quality of solid wells.
The filtration of vectors during the drilling process is moderate, rather than as low as possible. For example, drilling in the upper part of the well, low filtering vectors, smaller boreholes and high-water-prone indentation constrictions in the upper part of the surface, has resulted in the recovery of a drill encounter card and a obstruction of the lower drill. Instead, the upper layer is moderately larger when it enters, with a corresponding increase in the containment capacity of the filter, with relatively larger boreholes, which lower the lower layer, even though there is a certain hydro-inflated indentation of the upper part, but the relatively large borehole does not trigger the entry of the drill.
15. What are the hazards associated with the high liquid solid phase content of drilling wells?
Answer: (1) Reduced mechanical drilling speed and reduced operational life of the drill.
(2) Large filtration vectors, thick filtration cakes, high density, and the intrusion of well-drilling liquid filtration and solid phase particles into the oil reservoirs, destroying and reducing the production capacity of wells.
(3) The poor quality of the filtration cakes can lead to the introduction and downing of encounter cards, resulting in well leaks, well collapses, etc.
(4) Impacts on the quality of wells.
(5) Serious wear and tear caused by drilling rigs and boreholes, which were previously scrapped.
(6) The sand-sample recording well was disturbed, electron detection was not smooth and the information on the well was inaccurate.
(7) The amount of water consumed, the raw materials and the processor for drilling fluids.
In addition, the loss of water from the liquids of the positive gelatinous drilling wells is not easily low to prevent the underside complexity of the wells as a result of the high viscosity of the sedimentary fluids, the dissipation of sand or the absence of sand.
16. What hazards are to be addressed in a manner consistent with the low level of liquid retention in drilling wells?
Answer: (1) There shall be a sufficient amount of organic high molecular condensant, packaged or positive gel inhibitor in the drilling fluid to allow for the break-up of rock and clay from the boreal to the ground, so as to minimize the waterification and dispersion of the well back to the ground.
(2) The well-drilling fluid shall have sufficient rock carrying capacity to minimize the time for the return of the shard from the bottom of the well to the ground and be removed from the well-drilling fluids as quickly as possible.
(3) The equipment is equipped with solid controls to ensure its effective use.
17. What are the methods of solid phase control of well-drilling fluids?
Answer: (1) Chemical:
a. Chemical processor inhibits hydro-diffusion and the drilling of crumb bags.
b. Chemical processor coagulates small particles to facilitate removal.
(2) Physical law:
a. Dilution: reduced solid phase content due to water.
b. Natural deposition method: deposition through the circulatory system.
c. Replacement of partial well drilling fluids: replacement of part of the original well drilling fluids with low solid phase drilling fluids.
(3) Mechanical separation:
Use solid phase control equipment, forced removal. These three methods, which combine to achieve good control and solidity.
18. What are the hazards of over-sanding of well-drilling fluids?
Answer: (1) High sand content and increased solid phase content of drilling wells, resulting in lower drilling rate.
(2) High sand content, thick and loose filter cakes, poor adhesive performance, prone to indentations, and up-drilling pistons, resulting in well collapse and well collapse; The increase in the friction factor for the filters resulted in adhesive card drills, affecting the quality of the solid wells, electrometric encounter cards and inaccurate geological information.
(3) The high sand content caused wear and tear to the drills, rigs and mechanical equipment, reduced the useful life, increased the number of repairs and extended the drilling time.
(4) Increased drilling costs due to high sand content resulting in higher fluid solid phase content, unstable drilling fluid performance, increased number of treatments and increased use of processants
19. Methods of maintaining well fluids for rapid drilling in the upper layer?
Answer: (1) The slurry of the substrate is more soft, most of which is clay, mud, sand, current sand, etc., so as to ensure that sandy pellets are quickly sunk off the ground, and that the well fluids are kept low in sticky, low incision, low indensity and low solid phase content. Drilling fluids are mainly concentrated on high molecular polymer condensers and are accompanied by water thinning, with small recycles of about 50 metres prior to drilling, to be chemically treated and to form good filters to strengthen well walls.
(2) The drilling wells shall be replenished by continuous resupply of water, such as if the water is scarce and cannot be replenished, and shall cease to drill, adjust the liquid performance of the drilling wells, start drilling, etc., and cut off the long cycle of water, let alone force the drilling, so as not to complicate the boreholes.
20. What are the requirements for the drilling of wells in science?
Answer: (1) Use of high-quality well-drilling fluids facilitates access to complete and accurate geological and engineering information, facilitates the detection, protection of oil and gas layers and facilitates safe drilling of wells.
(2) The wells should be analysed in the light of the mineral composition of the rocks, and the oily material information and the size of the pressure of the layers should be selected for the appropriate drilling system and type, requiring the well fluids to have a low solid, low water loss, low resistance, strong sand carrying capacity and a good heat stability.
(3) Design of the drilling wells with a liquid density of 0.05 — 0.10 g/cm3 when they are opened, and 0.07 — 0.15 g/cm3 for the gas layer to achieve near-balanced pressure drilling, based on the geo-designed pore pressure gradient.
(4) The treatment agents used in the wells cannot affect the geological recording wells, and the additives are as acid solutions as far as possible in the carbonate rock formation and reduce the clay content.
(5) The well detection requirements are met.
(vi) Secured control equipment to ensure low sand content and solid phase content.
What are the measures to be taken to complete the electro-drilling of well fluids and to carry out engineering work?
Answer (1) 30-50 m before completion of drilling ceases to be directly integrated with powdered polymers for the treatment of well fluids and is designed to be evenly treated to make the performance stable and appropriate.
(2) Upon completion of the drill, when the diesel engine is retrofitted, the well is washed with a large charge, and when the basic non-drilled sift returns, the mud is duly increased to sticky, cut, so that the drilling can be measured.
(3) A large number of boreholes, a liquid borehole (generally 60-100s) equipped with high viscosity with CMC or other drugs before drilling, and short-lived drying through to the end of the borehole, can only be drilled for the purpose of lifting the boreholes with a spin rope.
(4) The drilling of well fluids on a continuous basis to avoid well collapse and blow-outs.
(5) When drilling takes place, the borehole is not open and the rig is then brought down to the bottom of the well, pumped, cleaned the borehole and drilled in a single car.
(6) In electrons, the drilling fluid shall be filled in a timely manner.
22. What are the main causes of electrocution?
Answer: (1) The type of well-drilled fluid is not adapted to the sub-well requirements, resulting in collapse and contraction, and the formation of a “sugar” borehole.
(2) The lack of structural strength of the well-drilling fluids and their low suspended capacity resulted in the sedimentation of the solid phase (heavy, drums) to form a “sand bridge”.
(3) Drilling has a large liquid filtering vector, resulting in a hydro-inflatable indentation of the draught, and permeating the sand layer into thick mud cakes.
(4) Low density of well drilling fluids, resulting in oil, gas and water intrusion, affecting the fluid performance of well drilling.
(5) High temperature increase and high temperature decrease, which results in less stable well-drilling fluids.
(6) Low charge, low upturn speed, and unclean carrying of rock crumbs, resulting in sedimentation at the bottom of the well.
23. What measures should be taken to prevent electrons and encounter cards from being measured in the eye of a “slubber” well?
(a) The well is sealed with high viscosity and is strictly prohibited in the section;
Repeated access to the well with a parent cone or a large cone, and removes the shoulder from it;
(b) Put the protor in the middle of the drill and use the protrusor to remove the problem with the upper shoulder;
(b) An eye-cutting of the “sergized” well segment by a wheel;
At the end of the drill, it carries rock chips and fallers with a large charge, then stabilizes and consolidates the wellheads with small charge (refruit speed) and then seals the wells with high viscosity, takes out the drying energy below the section of the wells and then finishes.
The addition of a bending tube or guidance for the lower part of the electron instrumentation is also very effective in eliminating electrocution in the “sugar” borehole.
24 – What’s the reason for the acoustic electrocution? How?
Acoustic electrons detection cause of resistance:
(1) The slurry is not allowed and there is a concrete plug in the tube;
(2) High-level and high-temperature density of the liquid phase of the drilling well;
(3) Poor capacity of well-drilling fluids to withstand calcium intrusion;
(4) Sedimentation due to the low suspension capacity of the well-drilling fluid;
(5) Drilling fluids are mixed with cement and dense.
Preventive approach:
(1) Accurate for the cement slurry and no cement plugs in the tube;
(2) Drilling wells have a suitable solid phase content, a stable performance, no high-temperature and low-temperature density, good suspension capacity and no sediment.
(3) Increase the anti-pollution capacity of well-drilling fluids, and improve the isolation fluids to avoid the denseness of well-drilling fluids and cement plasma.
What should be done with oil- and gas-infested drilling fluids?
Response: Following the oil and gas intrusion, the pump should be stopped and the well should be closed for pressure if the spill occurs. When wellheads are not spilled, the pressure of the pipe up and the pressure of the tube is zero, the increase should be determined by the degree of gas and oil intrusion. In the event of a serious increase in the oil and gas intrusion, the weekly density shall be increased by 0.03 ~ 0.05 g/cm3, so as not to cause a well leak too strongly. Cyclical observations, measurements of density, if performance is stable and density is not reduced, prove to have balanced the pressure of the surface. Short up and down drills can also be used to measure up and down the oil and gas velocity, and the increase in density can be at a rate not exceeding 10 m/h. In the event of serious contamination from well-drilling fluids, the treatment should be targeted and the gas should be drained. The increase is accompanied by a percentage supplement to polymers based on the amount of heavy crystal powder added, in order to increase the suspension capacity of well-drilling fluids and to reduce mudcake grinding.
The treatment of oil and gas incubated well fluids should be watered in appropriate quantities. Because when you’re dealing with oil and gas incubation, you need some water. Otherwise, well-drilling fluids are difficult to process, are not mobile, and are not easily discharged from the well-drilled fluids, and are not easily more dense.
26. What should be done to drill well fluids below the eastern battalion when they are drilled in an eye attack?
Answer: (1) Activate all purification equipment and, if necessary, use pharmacological fluids to reduce the solid phase content of drilling fluids.
(2) Dilution of well-drilled fluids to provide low viscosity, low cut-off, low solid phase content, low water loss and good fresco properties to stabilize the cut-off boreholes.
(3) Continuously replenish polymers to maintain sufficient polymer content in well fluids to control the dispersion of clays that enter well fluids when poaching.
What measures should be taken to drill well fluids as a result of an eye drill under the sand bridge?
Answer: (1) Underground drilling at the top of the sand bridge, pre-processing well-drilled fluids, maintaining good mobility, and then adding high-molecular polymers or active earth-moving to increase the yield of well-drilling fluids in order to facilitate sand.
(2) Large loads, small drills, eye.
(3) Activate the purification equipment and remove the removed sand in time.
(4) Stabilize the cut-off boreholes by incorporating high temperature precipitation and asphalt anti-frustration materials.
What measures should be taken to enter the mudshale collapse in the middle sandy-river street?
Answer: (1) Do not stop the pump in case of collapse, recycle the anti-depressants to 1 – 1.5% content and add anti-high temperature precipitation agents such as SMP to increase viscosity and to reduce the loss of high temperature and water, which will normally control the well collapse.
(2) The problem of collapse in the low density of well-drilling fluids is mainly due to the fact that the pressure of the column of liquids is not able to balance the pressure of the layer and can be resolved by increasing the density of well-drilling fluids to a design ceiling or higher, as appropriate.
(3) Due to the well-developed mudshale layer, which causes a severe collapse of blocks, when water loss is reduced and density is not significant, multi-ethanol resins are used to resist the collapse using membrane techniques.
(4) When the collapse problem is resolved, the pump will not stop until the sand is cycling clean, otherwise a large amount of sand will stop pumping, which may cause the drilling to be drilled, and the well is pre-drilled with high-compulsive drilling fluids (cipient viscosity 60-100S), which is strictly prohibited from being detached.