Example 1 Well W-29 in Dagang Oilfield
1. Raw data
(1) Surface casing: 339.7mm, depth102.53 m.
(2) Technical casing: 244.5mm, depth 998. 10m.
(3) Open hole: φ2 15.9mm bit, with drilling depth of 26 12m.
(4) Drilling tool structure: φ2 15.9mm drill bit +φ 159mm drill collar141.77m+φ127mm drill pipe 1505m.
2. An accident happened.
Run in to 1667. 1m, circulate drilling fluid, pump at 13.5MPa, and stop the pump when the gas pipeline explodes. After repair, start the pump. If the pump pressure rises to 20MPa, the movable drilling tool is invalid. The bit position is1658.11m.
3. Accident handling process
(1) The original drilling tool is screwed back and poured out at one time, and the fish falling length is1247.24m..
(2) After the original drilling tool is tightened, loosen it and turn it back, and trip out the drill pipe length 1490.52m and fish dropping length177.09 m..
(3) Lower the outside diameter 193.7mm and mill to1640 m..
(4) Run the jar to make the buckle, and the jar will release the card.
4. Understanding and suggestions
(1) When the pump was stopped in this well, a single pipe was lifted, including the Kelly, and the space was lowered for more than 20 meters, but it did not move at all when it was stuck, indicating that it was most likely to get stuck.
(2) This well has technical casing, and the easy-to-collapse layer has been isolated, so it is unlikely that the annulus will be blocked. It should not be collapse or sand bridge sticking, but sticking. If it is annular plugging, but not bit water hole plugging, it needs less than 20MPa to suppress formation leakage.
(3) The circulating drilling fluid in the middle of downhole drilling is normal, and the pump will get stuck after stopping the pump. It seems that the water hole of the drill bit is blocked, which is probably caused by backwater. Unfortunately, due to a small misoperation, I lost the opportunity to annotate the card agent.
(4) In this well, the explosive tube can be lowered, the water hole of the drill bit or the drill collar can be blown up, the circulation can be restored, and then the sticking agent can be added to relieve the sticking. This is much more dangerous than casing milling and back-screwing.
Example 2 T-49 1 Well in Henan Oilfield
1. Raw data
(1) Surface casing: 339.7mm, depth 50.64m m. ..
(2) Open hole: φ2 15.9mm bit, drilling depth 2 195m.
(3) Drilling fluid performance: density 1.03g/cm3, viscosity of 32s, and filtration loss of 8ml.
2. An accident happened.
Drill to a depth of 2195m, circulate drilling fluid and prepare for tripping out. Because the elevator can't be used, I waited for the elevator for more than an hour, but I didn't circulate drilling fluid and didn't move the drill string in time, which led to sticking.
3. Accident handling process
(1) Note that the card agent 12m3 was bubbled, and the card was finally released.
(2) Inject crude oil 10m3 for the second soaking, and finally release the card.
(3) Fill the card agent 12m3 for the third time, soak for 24 hours, and release the card.
4. Understanding and suggestions
(1) The drilling fluid density of this well is 1.03g/cm3, which is close to the density of seawater, and sticking still occurs, indicating that pressure difference is not the decisive factor.
(2) It is a big mistake not to circulate drilling fluid and move drilling tools in time and wait for the elevator for more than an hour.
(3) This well was stuck only after three consecutive injections of the releasing agent, which means that it cannot be stuck after one injection of the releasing agent, which does not mean despair. You can change the kind of adhesive release agent and soaking time, which may achieve the effect.
Example 3 Well F-23 in Shengli Oilfield
1. Raw data
(1) Surface casing: 339.7mm, with a depth of 84m.
(2) Process casing: 244.5mm, depth 1970m.
(3) Open hole: φ2 15.9mm bit, with drilling depth of 2994+04m.
2. An accident happened.
When drilling to 2994. 14m, because the first chain was broken, the drilling tool was lifted to 2 1m, and the chain was overhauled, but it was not lowered in time. After connecting the chain, the lifting drilling tool is lifted from the original hanging weight of 840kN to 1200kN, and dropped to zero. During the circulation, it was found that the pump pressure decreased from 16MPa to 8MPa.
3. Accident handling process
(1) Inject 40m3 mud remover to replace drilling fluid, and the pump pressure will be reduced from 12MPa to 10 MPa. 15 minutes later, it is found that the stuck release agent returns from the wellhead, and it is judged that the drilling tool is lost and the circulation is short-circuited. After testing, the leakage location is 1530m.
(2) Back-thread the original drilling tool, pour out the drill pipe1651.80m at a time, and pour out the lost drill pipe.
(3) Run the φ 127mm male cone three times, but all failed.
(4) Run φ 1 14 mm male cone for fishing. After fastening, hoist it to 1 100kN, stop for 3 minutes, and the hoisting weight will be reduced to 1000kN. After several activities, it returned to the original hanging weight of 840kN. Start the pump circulation, the pump pressure is normal, and the accident is relieved.
4. Understanding and suggestions
When circulating drilling fluid (1), it was found that the pump pressure dropped from 16MPa to 8MPa. If there is no problem on the ground, it must be that the drilling tool is leaking and the circulation is short-circuited. In this case, the sticking agent should not be recorded, but a period should be measured to determine the leakage position of the drilling tool, and then the drilling tool should be pulled out directly by back-screwing or blasting for the next step. The first injection of 40m3 of release agent is pure waste.
(2) It's very lucky to dump the drill pipe 165 1.80m at one time and dump the leaking drill pipe. Of course, this well has a technical casing of 1970m, which cannot be reversed once, but can be reversed again, and the upper part will not be stuck anyway.
(3) The drill pipe with the same diameter φ 1.27mm has different joint holes. When going into the well, you must measure and record them one by one, so that when an accident occurs, you can know what fishing tools to use. The fishing of φ 127mm male cone in this mine was ineffective for three times, and the fishing of the lower φ 1 14mm male cone was successful once, which may be caused by the unclear size of the joint nozzle. Every time we pull out the male cone, we should check what marks are on the male cone to help us identify the fish top. It is tolerable to make a mistake once, and it is very wrong to make similar mistakes again and again.
Example of Well B- 15-2 in Dagang Oilfield
1. Raw data
(1) Surface casing: 339.7mm, depth 202. 10m.
(2) Open hole: φ3 1 1. 1mm bit, drilling depth 1939m.
⊙⊙(3) Drilling tool structure: φ 365438+ 0 1. 1mm bit +φ 3 10mm centralizer 1.85m+φ 203mm drill collar 8.73m+φ 3/kloc. 0.87m+φ 203mm drill collar 26.25m+φ 178mm drill collar104.81m+φ127mm drill pipe1771.64m.
(4) Drilling fluid performance: density 1. 15g/cm3, viscosity 30s, filtrate loss 5ml, filter cake 0.5mm, shear force 5/1mg/cm2, sand content 1%, pH9.
2. An accident happened.
When drilling to the depth of 1939 m, the single pipe is stuck, and the single pipe is thrown, and then connected to the kelly to circulate the drilling fluid. The lifting drill string is lifted from the original hanging weight of 665kN to 1700kN, and is reduced to 200kN, which is invalid. The calculation card point is 18 14m. The bit position is1929.60m.
3. Accident handling process
(1) inject crude oil 18m3 and diesel oil 9m3, soak for18h, lift it to 1480kn, and pull out the drill pipe. The fish top well is 273.02m deep and the fish length is1656.58m.
(2) Printing under lead mold.
(3) The lower sleeve grinds shoes to repair the fish top.
(4) The female cone with φ 1 14 mm was used to make the buckle successfully, and the bad fish head was pulled out by loosening the buckle.
(5) Run the thread, loosen the thread at1761.53m, and pull out all drill pipes.
(6) Run the φ 3 1 1. 1 mm bit to dredge the borehole and circulate the drilling fluid.
(7) Lower the 244.5mm sleeve milling barrel155,49m, and perform sleeve milling from 176 1.53m to1912,59m (the uppermost centralizer position).
(8) Run the upper firing pin to stab and shake the release card.
4. Understanding and suggestions
(1) After filling the sticking agent, the movable drilling tool should be limited to some extent. It is not advisable to lift it more, but to pressurize it more, because at this time, the sticking agent is mainly relied on, not the pulling pressure. If the drilling tool is unplugged, the water hole may be blocked, and the sticking agent cannot be discharged, which will cause the borehole wall to collapse and block the annulus, thus losing the possibility of refilling the sticking agent.
(2) For the drill pipe used, be sure to know clearly what grade it is. What grade? How long has it been used? What complicated situations have you experienced? The tensile and torsional strength of the new drill pipe cannot be calculated. So it is not presumptuous to mention 1700kN.
(3) Generally speaking, the fish head is straight, and there is no need to make a lead seal or fish head, because the fish head can be inferred from the fracture. You can directly lower the slip fishing tube or female cone for fishing, which can buy time and restore circulation.
(4) The drill collar is stuck in this well. There is no need to waste so much time if it is handled well.
Example 5 Well L-3 in Qinghai Oilfield
1. Raw data
(1) Surface casing: 339.7mm, 402m deep. ..
(2) Technical casing: φ 244.5mm, depth 3601.63m. ..
(3) Open hole: φ2 15.9mm bit, with drilling depth of 5086m m..
(4) Drilling tool structure: φ2 15.9mm bit +φ 177.8mm drill collar110.82m+φ127mm drill pipe.
(5) Drilling fluid performance: density 2. 14g/cm3, viscosity 58s, filtrate loss 5ml, filter cake 0.5mm, shear force 12/27mg/cm2, sand content 0.5%, pH 1 1.
2. An accident happened.
The design depth of this well is 5200m, and the actual drilling is 5086m. It takes 6 minutes to connect a single joint, the bit position is 5076.64m, and the maximum pulling force is 2000kN, which is invalid. The circulation is normal, and the pump pressure is 2 1MPa. Calculate the position of the card point 4200m.
3. Accident handling process
In the middle of winter, the temperature in Qaidam basin is very low, and the well is more than 200 kilometers away from Lenghu base, so it is difficult to organize crude oil pulling, and the density of crude oil and drilling fluid is very different. It is even more unconditional to have a card remover ready. However, the basin is full of high-concentration and high-density salt lakes, which are not frozen in winter, so we decided to use local materials and soak them in high-concentration salt water. Inject 50m3 of saline water with the density of 1. 18g/cm3, soak for 15 minutes, and the card will be released.
4. Understanding and suggestions
(1) It is a pioneering work to soak the card with salt water in Qaidam Basin. Not only L-3 well, but also J-2 well, E-3 well and NC- 1 well. Deep wells can be used, and shallow wells can be used. Not only crude oil is saved, but also the construction is more convenient.
(2) The stuck pipe needs to be soaked with salt water. In the Qaidam Basin, one characteristic is that the bubbles in the shaft wall do not collapse, and the stability of the shaft wall should be considered in other areas.
(3) During construction, salt water and fresh water drilling fluid must be separated by fresh water or diesel oil, otherwise the slurry cannot be pumped after thickening.
Example 6 Well H-26 in Jianghan Oilfield
1. Raw data
(1) Surface casing: φ 323, 85 mm, depth 85 m. ..
(2) Open hole: φ2 15.9mm bit, drilling depth 2142.53 m.
(3) Drilling tool structure: φ2 15.9mm bit +φ 178mm drill collar112.35m+φ139.7mm drill pipe.
(4) Drilling fluid performance: density 1.20g/cm3, viscosity 28s, filtration loss 17ml, filter cake 2mm, shear force 0/8mg/cm2, sand content 2%, pH 8.
2. An accident happened.
When drilling to 2 142.53m, the faucet flushes the pipe and pricks the packing, and the faucet sits on the turntable to change the packing. There is no circulating drilling fluid and no movable drilling tools. After replacing the packing, the start-up cycle of the pump is normal, but the drilling tool is stuck near the surface casing shoe.
3. Accident handling process
This well needs1100m3 soaking agent. It's rainy season and the roads are muddy, so it's difficult to haul crude oil. Therefore, it is decided to soak in stages and actually inject 48m3 of crude oil. Soak the lower section first, and then change the crude oil to the upper section at a time after four hours. After soaking for two hours, the hanging weight was increased from the original 750kN to 1000kN, and the card was released.
4. Understanding and suggestions
(1) It is a serious violation of operating procedures to sit on the turntable and repair the faucet. In this way, it is strange not to circulate drilling fluid, move drilling tools and get stuck.
(2) The well is stuck in the whole interval, and more than 80% of the interval is mudstone. It doesn't make sense if it is explained by pressure difference theory alone.
(3) In the case of sticking in the whole interval, soaking in stages is a good method, which not only saves a lot of sticking remover, but also keeps a certain liquid column pressure in the annulus.
Example 7 Well S-3 in Jianghan Oilfield
1. Raw data
(1) Surface casing: φ 323.85m, depth106.05m.
(2) Open hole: φ2 15.9mm bit, with drilling depth of 2453,20m.
(3) Drilling tool structure: φ2 15.9mm drill bit +φ 177.8mm drill collar101.53m+φ139.7 mm drill pipe.
(4) Drilling fluid performance: density 1.26g/cm3, viscosity 37s, filtration loss 12ml, filter cake 1.2mm, shearing force 6/ 17mg/cm2, sand content 2%, pH 9.
2. An accident happened.
Drill to 2453.20m, circulate drilling fluid and prepare for tripping out. However, the chain piece of the winch transmission chain flew out and was repaired with the shutdown for 20 minutes, and the drilling tool could not move and was stuck. The calculation card point is 1730m.
3. Accident handling process
(1) Circulate drilling fluid normally, and prepare to soak crude oil, with a pump pressure of 8MPa. Because both pumps are out of order, stop the pump for repair. After the pump is repaired, the pump pressure rises to 15MPa when the pump is started, and the circulation is blocked. It is considered that when the backwater is discharged, the drilling fluid flows back, blocking the water hole of the bit and cutting off the oil soaking path.
(2) Run the 48.3mm explosion tube, and prepare to explode near the drill bit, blow up the drill bit or blow up the drill collar, but when it is lowered to 2354m, it is stuck and the drill bit cannot be lowered.
(3) It is decided to start flushing from φ 139.7mm drill pipe, run 40.26mm oil pipe 150m with drill bit and 60.3mm oil pipe for 2300m, and circulate drilling fluid to the position of drill bit by cement truck through the water hole.
(4) Lower the 48.3mm explosion tube to the upper part of the drill bit to explode and restore circulation.
(5) Inject 20m3 of crude oil, diesel oil 10m3, soak 1 1 hour for 20min, and release the card.
4. Understanding and suggestions
(1) This is a special and successful treatment. Instead of going back, we tried to open the channel and soak the card release agent to release the card. On the one hand, it saves time, and more importantly, it avoids the risk of retrogression. After the sticking is released, trip out together with the drill bit. Neither the drill bit nor the drill collar exploded, but only two cracks with a longitudinal length of about 1.5m were exploded.
(2) This method of blasting tunnel is meaningful only if the annulus is not blocked. Therefore, it is necessary to organize closely to gain time and open the circulation channel before the borehole wall collapses.
(3) It is very important to keep the circulation path after sticking. Under any circumstances, the drilling fluid is not allowed to flow backwards. Therefore, if you want to repair the pump, you must first close the cut-off valve on the high-pressure pipeline. It is best to install a back pressure valve on the drill pipe to avoid human error.
Example 8 KS- 1 well in southern Xinjiang
1. Raw data
(1) Surface casing: 500mm, with a depth of 280m.
(2) Technical casing: 339.7mm, with a depth of 3570m.
(3) Open hole: φ3 1 1. 1mm bit with drilling depth of 5015.85m. ..
(4) Drilling tool structure: φ 311mm bit +φ 203mm drill collar 81m+φ 203mm jar while drilling +φ 127mm weighted drill pipe+φ/kloc.
2. Accident occurrence and treatment process
This well was stuck in the same interval many times, which took nearly a hundred days.
(1) First sticking: drill to the well depth of 50 14.08m, drilling fluid density 1.42g/cm3, wellhead overflow, hourly 1 1.5m3, and return drilling fluid density1. When the drilling fluid density is increased to 1.72g/cm3, there is still overflow at the wellhead. When the drilling tool is moved, it will get stuck. The original hanging weight was increased from 1650kN to 2200kN, and then pushed down to 400kN, and the card was released.
(2) Second sticking: When drilling to 50 15.85m, the drilling fluid density decreased to 1.42g/cm3, and then increased to 1.76g/cm3. When the drilling tool is stuck when moving, it is lifted to 2400kN from the original hanging weight 1650kN, and pressed to 400kN, and it is invalid to turn 15 turns. The processing steps are as follows:
① Note that the card agent 12.4m3 is invalid after soaking for 42 hours.
(2) Pay attention to that the card agent soaked in 20m3 for 35 hours and 30 minutes is invalid.
③ Increase the density of drilling fluid in the well to 1.85g/cm3, pay attention to the plugging agent of 27.5m3, and then shut in and soak. After 7.5h, the riser pressure rises to 3.2MPa, the calculated bottom hole pressure should be 94. 1MPa, and the drilling fluid density for balancing formation pressure should be 1.88g/cm3. * * * Soaking for 7 1 hour for 40 minutes is invalid.
(4) Measure the stuck point at 3660m with a stuck tester.
⑤ Pull out the upper drilling tool after loosening the back thread successfully at 3640m. ..
⑥ Lower the 244.5mm sleeve milling cylinder to180m and sleeve milling to 4057m.
⑦ Trip in and make up, and when it reaches 2 100kN, the sticking will be released by shock.
(3) Third sticking: After the second sticking is released, trip in to 4 102.54m, take over the pipe, and stop the activity for 3 minutes before getting stuck. The processing steps are as follows:
① Inject 3 1.45m3 with the density of 1.95g/cm3, and soak for 6 days without releasing the card.
(2) From 3650m, loosen the back thread and pull out the upper drilling tool.
(3) Lower the jar for threading, which is 1800kN, and release the jar.
(4) The fourth sticking: trip in to 4 107m and get stuck. It is mentioned that 1500kN is pressed down to 800kN, and the card is released forcibly.
(5) The fifth sticking: trip down to 4862m and get stuck. Release the card from the original hanging weight of 1500kN to 1800kN. Lift the five pillars up and get stuck, and press 600kN to release them. Pull up the single chip and get stuck, and press down 800kN to rotate and release it. At 4 106m, the card is stuck again. When the force is lifted 1400kN, the card is released.
(6) sixth sticking: drill after drilling to 4,995 m; when lifting to the sixth column, lift it from the original hanging weight 1.350 kN to 2 1.20 kN, and press it down to 300kN, and the rotation is invalid, resulting in sticking. The processing steps are as follows:
(1) Pull out the upper drilling tool from the place where the back thread is loosened by 3655m blasting.
② When the jar is buckled, the jar is invalid.
(3) Back off from 3655 meters and pull out the upper drilling tool.
④ Run 244.5mm sleeve milling cylinder, sleeve milling and back-screwing. When the sleeve reaches 4 100m, the card will be released. ..
3. Understanding and suggestions
(1) This well has reached the point where continuous sticking is almost impossible. The reason is that the high-pressure brine layer is unstable, and it is not recognized that the high-pressure brine layer is the main reason for sticking. In the process of drilling, as long as you encounter a high-pressure saline layer, no matter how much water is produced, you must resolutely crush it. Both engineers and geologists should have a unified understanding of this, and there should be no ambiguity. Otherwise, the trouble will be endless. After expert argumentation, the drilling fluid density of this well increased, and the high-pressure brine was stably stratified, and it was successfully drilled to 642 1 m.
(2) Before soaking the release agent, be sure to measure the position of the blocking point, and the liquid level of the release agent must exceed the blocking point. According to the previous treatment, the main sticking position of this well should be between 3660-4 100m, but the first sticking agent is marked as 12.4m3, which can only soak to 4850m ... The second sticking agent is 20m3, which can only soak to 4750m. For the third time, I noticed that the dosage of plugging agent was 27.5m3, and only 4670m was soaked, and the plugging point could not be soaked at all. After the third sticking, inject 3 1.45m3 sticking release agent, which can only soak to 3,700 m and cannot reach the sticking point. No wonder the card remover doesn't work. No wonder it didn't work after soaking for six days. This leads to the wrong conclusion that the sticking release agent is not suitable for this well, so it is incredible that the sticking release agent is no longer used. Please note that the third stuck bit can be jarred to release the stuck bit. The release agent plays a role, which has been soaked to less than 50m away from the sticking point, and can be jarred to release the sticking.
(3) Due to technical errors and cognitive errors, after the third sticking, the sticking agent is no longer needed, and the sticking accident is alleviated by blasting and milling. You know, this is a dangerous practice, but also a last resort. Fortunately, the formation conditions in this area are good and there is no collapse. After repeated milling, the water hole of the drill bit is not blocked and the circulation path can be maintained. If the same practice happens in the eastern region, it will be impossible to clean it up. The biggest feature of this well is that it is not stuck below 41000 m. If it is stuck from 3660m to 5000m, it is difficult to solve the problems of casing milling and back-off. Even if the problem can be solved, it will take about a year if it goes well, and it will be hard to say if it doesn't.