Two flooded wells in yanmazhuang coal mine

1. Two oil well water injection processes

Yanmazhuang Coal Mine has an annual output of 450,000 tons, with monoclinic structure, developed faults and close hydraulic connection. Large water inrush has occurred many times, and the normal mine water inflow is 90 ~ 120m3/min.

March 8 1979-200m horizontal dongda lane No.2 1 track excavation, the roadway encountered L8 limestone fault in the early shift, with a drop of 8m. After stopping digging to reinforce the roadway for 32 hours, on March 9 14: 30, a piece of water seepage was found in the tunnel face. 14: 45, black water flowed on the rock wall and made a "bang bang" sound, and then evacuated the crowd to close the sluice; 15: 00 and 10: 00, and the water volume has reached 138m3/min (including raw water volume of 39.5m3/min); At 15: 08 and 15: 00, the water quantity was 14 1m3/min, the flow velocity was 1.3m/s, and the water depth was 0.7m At the sluice, water suddenly rushed out of two empty harvesters and fell into the sluice. At that time, the water depth was 1. 1m, and the velocity was rapid. A dozen comrades-in-arms struggled desperately, tying the harvesters with cables and unable to pull them. At 15: 40, the water volume has reached 283m3/min (water inflow is 240.9m3/min), and the displacement of all eight pumps is only 56m3/min, which is unbearable. 15: 53 The pump house was flooded, and rescuers were forced to evacuate when the water depth was 1.5 m, and the water level was completely flooded at 15:57-200m for 68 minutes. Water goes straight up the dark inclined shaft and reaches -75 m at 18 and 15. All 28 large pumps in 3 pump houses were started, and the displacement reached 1.96 m3/min, but the water potential could not be suppressed. Finally, from 19 to 14 to 28, the water pump cable stopped running and the whole well was flooded. The delay from water inrush to well flooding is only 4 hours and 43 minutes. After the water inrush, the water level of Ordovician limestone in the whole mining area spread, especially along the Fenghuangling fault for more than 23 kilometers. The maximum drop of L2 water level is 35m, and the maximum drop of L8 water level is 2m. The water inrush elevation is-195m, and the water pressure is 28.2kg/cm2. N6 grouting drilling found that there were 7 caves under the roadway at 18.7m, with the cavity height of 0. 13 ~ 3.54m, the total height of 8.03m, and the aperture of 0.65m This layer is located in L2-L4 limestone, and the penetration ratio is 1.53.

After water plugging by grouting, the horizontal production of -75 m resumed on 1982, and the mine water inflow was 80 ~ 62 m3/min. Hanwang coal mine is affected by drainage, and the water volume has a downward trend. After three and a half years of drainage, it is considered that the water inrush point has been blocked. Two-stage drainage began in May 1985, and the water volume at -75m 18m3/min. It is expected to be discharged to the water level of -200m, with a water volume of 23.8m3/min and a displacement of 30 ~ 40m3/min. When the submersible pump started, the water level dropped to-188.2 m at 2 1: 57 (i.e. 14) on the first day, and the water level stopped falling for 67 hours and 33 minutes, with a displacement of 3 1.4m2/min. 17, 15: 30, the water volume suddenly increased to 42.6m3/min, and the water level rose sharply. Underground personnel heard several loud noises. The rising speed of water level will flood the inclined shaft from 1m to 1m within 10s, and the estimated water volume is 320m3/min. At 22:00 10, the water level reaches -75m, and the water inflow 198m3/min. In addition, the water volume of Dongda Lane is 20m3/min, and the total water volume is 186m3/min. Finally 18 was flooded at 0: 38, which lasted for 9 hours and 8 minutes.

2. Causes of well kick

1) The original water inrush point is not strong enough for grouting and water plugging. During grouting, only N6 borehole injected 694t of cement, accounting for 70% of the total water injection, and injected 53 1m3 of gravel, accounting for 89% of the total water injection, so the effective reinforcement range was limited. At the same time, the quality of cement is poor and the combination of cement and sand is not good. Although the water is basically blocked, and after four years of drainage test at -75 m level, the water pressure at the water inrush point is 15.9kg/cm2, and the breakthrough ratio is 0.85. When the water is chased to-188.2 m, the confined water pressure rises to 27.2kg/cm2, and the breakthrough ratio is 1.45, and the water inrush point has exceeded the breakthrough critical value of the intact zone 1, resulting in the original water inrush point being broken again.

2) There is no waterproof gate between the second floor and the first floor.