The drilling project must be strictly in accordance with the provisions of the "Regulations on Coalfield Drilling", and the "Construction Design of Drilling Project" should be compiled before the start of construction, and the acceptance should be carried out in strict accordance with the "Quality Standard for Coalfield Geological Exploration Drilling Project" after completion. The drilling quality requirements are dart and Grade A, and the quality of minable coal seam is excellent, with the qualification rate of 100%. So as to improve the drilling quality. Special requirements are as follows:
(1) coal coring
Take coal core samples and gas coal samples from 3 # coal seam of the target coal seam, the recovery rate of coal core length is not less than 75%, and the weight recovery rate is not less than 60%.
(2) coring
Core control Q bottom boundary, Q bottom boundary to J, core every 50m between bottom interfaces, core from coal seam roof and floor, and take appropriate cores to measure rock inclination. The average core recovery rate meets the following requirements: the recovery rate of coal-bearing strata is ≥ 70%, and the recovery rate of non-coal-bearing strata is ≥ 60%.
(3) the final drilling horizon
Drilling to the bottom of 3 # coal seam 20 meters can stop.
(4) Drilling and sealing
Borehole sealing shall be carried out in strict accordance with the requirements of Detailed Rules for the Implementation of Borehole Quality Standards. From 200m above the roof of No.3 coal seam to the final hole position, it is completely closed, and the upper and lower interfaces of Q and ABOVE Band (E) are closed for 30m ... The quantity of hole sealing cement shall not be less than R32.5, and the mass ratio of cement, sand and clean water shall be 1: 1: 0.65. Pump the mortar to the closed section, and sample the top surface of the mortar for inspection. If the surface of mortar is 5m lower than the design requirement, it must be sealed and the orifice mark should be buried.
(5) Verification of hole depth
When drilling 100 m and the roof and floor of coal seam and the final hole, the total length of drilling tools should be measured and adjusted reasonably.
(6) Hole inclination measurement
Keep the drilling as straight as possible, which is in line with the super-class and first-class standards of coal exploration Drilling Engineering Quality Standard.
(7) Simple hydrological observation
Do a simple hydrological observation. In case of water inrush, water leakage and karst cave during drilling, the hole depth should be recorded in time to observe the water inrush and water leakage.
(8) Original records of drilling
The class report requires timely records, complete contents, accurate data, clear filling and complete preservation.
(9) Drilling requirements
The drilling hole is straight, and the final aperture is 93mm.
(10) coal sample collection
All minable coal seams shall take full-thickness coal core samples and gas coal samples according to the specification requirements. The coal core samples and gas coal samples taken shall not contain mixed, polluted and sintered substances.
(1 1) Conventional logging
Carry out conventional digital logging, simple temperature measurement and acoustic logging.
Drilling construction process in 4.2.2.2
1) On October 29th, 2008165438+/kloc-0, a three-wing centerless drilling rig with a diameter of φ9 1mm was used to drill the hole to a depth of 329.47m, which has passed the bedrock interface. Then, when drilling with 89mm circular diameter coring bit or φ9 1mm diamond centerless bit to the hole depth of 92 1.68m, grooves appeared. After the trench was leveled, conventional logging was carried out on June 5+February 36, 2008. Surround the hole to 3 15. 19m with an reamer with a diameter of φ168m, then lower the φ 127mm retaining wall, and use 1: 0.6 cement slurry to plug the annular gap between the casing and the hole wall, with the plugging interval of 0 ~ 3/kloc. Let it stand for 70 hours and wait for the cement slurry to set.
2) After drilling to the original hole depth of 921.68m, use φ9 1 mm diamond centerless bit or φ 73mm rib coring bit to continue intermittent coring drilling to the hole depth of1384.77m. Due to insufficient equipment capacity, the drilling rig was changed to XB-167m on March 6th, 2009. An accident occurred when φ9 1mm diamond centerless bit or 73mm rib coring bit was intermittently drilled to 1449.90m, and the accident treatment time was from March 10 to March 26th, 2009.
3) Continue drilling with φ9 1mm diamond centerless bit or φ 73mm rib coring bit to the well depth of1606.57m. After the second conventional logging, total leakage occurred when drilling to the well depth of 1670.09m after plugging, and continue drilling to the final well depth of178/kloc.
4) Conventional logging was conducted on May 2009 1 1, and the hole was stopped on May 2009 12, and the hole was sealed according to the hole sealing design (see the figure below for hole sealing).