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LM-200 reverse well drilling rig Shisanling Pumped Storage Power Station construction case

Source: xe1x.com Author: admin Date: 2019-03-05 14:55 heat:
Construction case of reverse rig for Shisanling Pumped Storage Power Station
4.1 Overview
Shisanling Pumped Storage Power Station is a key construction project to change the quality of power supply in Beijing. It is located in the left bank of Shisanling Reservoir in Changping County, Beijing. The Shisanling Reservoir was used as the lower pond, and an energy storage upper pond was constructed on the mangshan on the left bank of the reservoir. In the construction of power stations, the construction of inclined pressure pipelines is difficult, which is the key to power station construction. In order to speed up the construction speed, an industrial experiment of drilling a pressure pipe with a back-drilling rig was carried out. The experimental section is the downward slope of No. 2 pressure pipeline. From the construction branch tunnel in the middle of the pressure pipeline to the north exploration tunnel, the excavation section is D5-5.6m, the net section is D4.4-3.8m, and the horizontal angle is 50 . The rock that passed through was mainly conglomerate of complex composition, and the rock mass was slightly weathered to fresh state II-IV rock mass with cracks developed. There are F 2 , F 15 , F 16 , F 14 , F 20 faults and gabbro veins along the line. The faults are generally 1-3 m wide, with an influence zone of 2-5 m and good water permeability.
4.2 Selection and modification of reverse well drilling rig <br /> According to the engineering conditions of No. 2 pressure pipeline, choose LM-200 reverse well drilling rig. By calculating the relevant parameters, the machine can basically meet the engineering requirements. But because the machine is designed for underground mine conditions, the borehole inclination angle is 60-90 . This test uses it to drill inclined holes with an inclination angle of 50 . The rig needs to be modified. The main parts of the transformation are: the main machine, the stable drill pipe, and the drill pipe conveying device.
4.3 Anti-inclination measures <br /> Pilot holes are the key in reverse well drilling construction. Its success or failure is related to the success of the entire drilling operation. This is the first time in China to use a reverse-drilling rig to construct a large-inclined deep-hole project. There is no mature experience to draw on. The rock in the lower slope of the No. 2 pressure pipeline is a complex conglomerate. The rock is poor in homogeneity, and the fractures and structures are very developed. . And for oblique holes, not only the change in the top angle of the borehole will cause deflection, but the azimuth change will have a greater impact on deflection, so it must be technically prepared to take reliable drilling measures to control the deflection of the borehole.
⑴ Select the appropriate drilling parameters
The main factor that affects the deflection of the borehole is the weight on bit. By calculation, for the LM-200 reverse well drilling rig, when the weight on bit is greater than 60kN, the drill pipe may be unstable, so it is best not to exceed this value. However, under this weight-on-bit, the drilling speed is relatively low. You can increase the unstabilized force by increasing the stability of the drill pipe, increase the weight-on-bit, and increase the drilling speed. For complex conglomerate, the weight on bit is controlled at 10kN and the drilling speed is about 1.0-1.5m / h. The principle of drilling parameter control in this test is: 50m before drilling, low drilling pressure, high speed and constant drilling speed. With the increase of the drilling depth, the friction resistance increases rapidly, and the speed is gradually reduced, and the drilling pressure is appropriately increased to keep the drilling speed uniform.
⑵ Add stable drill pipe
The outer diameter of the stabilized drill pipe is basically the same as the diameter of the borehole. It keeps the drilling tool in the center of the well and reduces the deviation of the drilling hole caused by the bending of the drilling tool due to the increase in weight. In order to achieve the purpose of anti-deflection, at least three stable drill pipes are arranged, that is, a near-bit stable pipe, a middle stable pipe, and an upper stable pipe. According to the specific situation of the pressure pipeline, appropriately increase the stable drill pipe and adjust it according to the results of the slope measurement.
⑶ Mud parameter control
The geological conditions of the lower slope of the No. 2 pressure pipeline are complicated, and various structural developments may occur in holes such as slurry leakage, hole collapse, and buried drilling. In order to avoid or reduce the occurrence of accidents in the holes, high-quality NV-1 sodium soil is used to prepare mud as well washing fluid. The design mud parameters are shown in Table 4. During the drilling process, the mud number was further adjusted according to the formation conditions.
Table 4 Design mud parameter table
Mud parameters Control range Mud parameters Control range
Viscosity / s 20-30 proportion 1.04-1.10
Water loss / ml (30min) -1 10-15 Mud thickness / mm 0.7-1.4
Shear force / mg cm -2 0-40 PH value 8-9
Sand content /% 1 Colloid rate /% > 97
In order to ensure the orientation of the boreholes, three inclination surveys were carried out during the drilling of the pilot holes. The measuring instrument used is a JJX-3 well inclinometer, which adopts the electromagnetic principle and uses an azimuth mechanism with screw positioning and a 360 circuit. It has no drift issues. The instrument's error index: azimuth error: 2 , vertex angle error: 10 '.
4.4 Drilling work <br /> After the transformation of the LM-200 reverse well rig was completed, the rig was transported to the site and installed on 1992-06-04. The pilot hole was drilled on June 26 and installed on August 4 Reaming drill bit. On August 17, a deflection guide well of No. 2 pressure pipeline with a depth of 203m and a diameter of 1.4m and an inclination of 50 was completed. The technical statistics of drilling are shown in Table 5. Since then, the lower slope of No. 1 pressure pipe and No. 2 pressure pipe of Dachaoshan Power Station have been constructed.
Table 5 Guidance Statistics of No. 2 Pressure Pipeline Drilled by Reverse Drilling Rig
Work content Workload Working time / h Reach the target
Pilot hole drilling Diameter 216mm, depth 203m 370.75 0.55m / h
Reaming drill bit 6
Reaming drilling 1.4m in diameter and 191m in depth 240.75 0.79m / h
Reaming and rock breaking 293.87m 3 240.75 1.22m 3 / h
Hole forming speed 130m / month
Pure hole forming speed 222.7m / month
Drilling deviation 1.1%

Keywords: reverse rig construction, LM-200 reverse rig
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