(1) Jixi mining area
Jixi mining area is located in the southeast of Heilongjiang Province, with an area of about 3375km2. The coal-bearing structure consists of Jidong depression in the north and Muling depression in the south. Coal-bearing strata are Chengzihe Formation and Muling Formation of Lower Cretaceous, with more than 60 coal seams and a cumulative thickness of 5 ~ 20m. Thin coal seams are dominant, followed by medium-thick coal seams, with large coal seam spacing and poor stability. The grades of coal are mainly gas coal, long flame coal and coking coal. Jixi Mining Group Company is the main coal development enterprise in the mining area, with 2 coal mines 12, 20 mines under construction and 2 mines under construction, and the designed coal production capacity is1.600×1.04t/a. ..
1. Mine gas emission
(1) all belong to high gas mines except Hengshan coal mine, and the relative gas emission is10 ~100 m3/t d, generally15 ~ 30m3/t d; The gas emission in Jidong depression is higher than that in Muling depression.
(2) Judging from the composition of mine gas emission, most of them are mined-out areas (including surrounding rock and adjacent layers), accounting for 60% ~ 80%.
(3) The gas emission of working face varies with coal seam and mining sequence. Take the first mining area in the east of Chengzihe shaft as an example: when the No.37 coal seam is first mined, the absolute gas emission of the working face is 2.5 ~ 6.8m3/min; When No.39 coal seam is mined in the lower part and No.37 coal seam is mined, the absolute gas emission of the working face is only 0.3 ~ 0.44m3/min.
(4) From the composition of gas emission in the working face, this layer emission and the upper adjacent layer emission are the main ones, accounting for about 50% respectively.
(5) From the coal group, the gas emission from the heading face of Muling Group is higher than that of Chengzihe Group.
(6) All mines have local abnormal gas emission. Taking No.30 coal seam in Chengzihe Coal Mine as an example, the absolute gas emission of fully mechanized working face with vertical depth of 450 ~ 500 m is generally about 7 ~ 22 m3/min, while the gas emission of fully mechanized working face west of 145 (with vertical depth of about 470m, mining No.30 coal seam) is 33 ~ 37 m3/min, which is 70% ~ 65433 higher than the normal value.
(7) In12 high gas mines, Didao Mine and Datonggou Mine are coal and gas outburst mines, while Donghai Mine and Chengzihe Mine are gas outburst mines.
2. Coalbed methane reservoir
The coal exploration at 1000m is shallow. The measured coal seam gas content (combustible basis) in Vascon area is 3.49 ~ 8. 12m3/t, the methane concentration of coalbed methane is 66% ~ 95%, the gas saturation is generally 60% ~ 70%, and the depth of coalbed methane weathering zone is generally 200 ~ 300m. Most of the coal bodies are primary structures with five groups of cleavage fractures, and the porosity is 1.4% ~ 4.2%. The measured permeability of coal seam by downhole drilling flow method is 0.001~ 0.005 m d, the measured maximum gas pressure is 5.8MPa (vertical depth is 647m), and the measured average gas pressure gradient is 0.6 MPa/100 m.
3. Coalbed methane resources
(1) coalbed methane resources
The total CBM resources in Jixi mining area (production mine and mine under construction) are 80.25× 108m3, and the total recoverable CBM resources are15.81×108m3. In the total resources of coalbed methane, the resource consumption is 16.68× 108m3, accounting for 20.8%. The remaining CBM resources are 63.55× 108m3, accounting for 79.2%. The consumption of coalbed methane resources consists of two parts: drainage consumption and exhaust consumption. The drainage consumption is about 1.28× 108m3, accounting for 7.7%; The exhaust air consumption is 15.40× 108m3, accounting for 92.3%. The remaining recoverable resources of coalbed methane are 12.59× 108m3. The remaining coalbed methane resources in goaf are 1.99× 108m3.
(2) CBM resource categories
See Table 7-4 for the evaluation parameter values and scores of coalbed methane resources in various mines in Jixi mining area. The evaluation scores of coalbed methane resources in the mine are 130 ~ 160, 1 1. According to statistics, 1 belongs to Grade II, and the coalbed methane resource is 3.07× 108m3, accounting for 3.8% of the total resource. 10 mine resources are classified as class iii, and the coalbed methane resources are 77. 18× 108m3, accounting for 96.2% of the total resources (table 7-4).
Table 7-4 Classification and Evaluation Parameters of Coalbed Methane Resources in Jixi Mining Area
(II) Hegang Mining Area
Hegang mining area is located in the northeast of Heilongjiang Province, covering an area of about 2800km2. The coal-bearing structure (Hegang basin) is a long dustpan monoclinal structure with nearly north-south direction and east inclination; The main coal-bearing stratum is Shitouhezi Formation of Hegang Formation of Lower Cretaceous, with more than 40 coal-bearing layers, of which 36 are recoverable and partially recoverable. The cumulative thickness of minable coal seams is 50 ~ 80m, most of which are medium-thick coal seams, some of which are extra-thick coal seams, and the thickness of coal seams varies greatly. Coal ranks are mainly gas coal and fat coal. Hegang Mining Group Company is the main coal development enterprise in the mining area. At present, it has 9 coal mines with a coal production capacity of1500×104t/a. ..
1. Mine gas emission
(1) 9 production mines such as Xing 'an, Junde, Nanshan, Yixin (Xinyi) and Xingshan, among which Nanshan and Yixin are coal and gas outburst mines; The four mines of R&F, Continental, Zhenxing and Lingbei are low gas mines.
(2) The absolute gas emission and relative gas emission in Nanshan Mine are much larger than those in other mines. In 2004, the absolute gas emission of Nanshan Mine reached 1 12.68m3/min, and the relative gas emission reached19.37m3/t d. The gas emission of Junde Mine and Xing 'an Mine was also relatively large.
(3) With the deepening of mine production to the deep level, the gas emission increases sharply. 1988, the absolute gas emission of the company's mine was 105.66m3/mim, which increased to 188.88m3/min in 1998 and reached 2 18.83m3/min in 2004. The annual increase exceeds 10%.
(4) Mine gas emission presents a distribution of high in the north and low in the south. Xingshan, Xinyi and Nanshan mines in the north are high gas mines, and the gas emission from the three mines is 150.02m3/min, accounting for 62.6% of the total. Except Xingshan Mine in the south, the others are all low gas mines, and the relative gas emission of Xingshan Mine is only 8.23 m3/t d. ..
(5) The gas dynamics phenomenon in the fault structural belt is remarkable. For example, the gas pressure in the F 14 fault zone of Nanshan Mine is 1.8MPa, coal and gas outburst occurs near the fault, and gas emission occurs when the vertical borehole (φ325) touches the F 14 fault; When No.22 coal seam in Xingshan Coal Mine is close to the fault, gas gushes out, and the gushing amount is 1.8m3/min.
2. Coalbed methane reservoir
At the depth of 800 meters, the measured gas content (combustible basis) in the coal seam of He 02 coalbed methane well is 1.06 ~ 5.0 1m3/t, and the methane concentration of coalbed methane is 60% ~ 90%. The gas saturation is generally about 10%, the gas gradient is generally 0.8 ~ 1.0m3/t 100m, and the depth of the weathered zone of coalbed methane is generally 220 ~ 350m. Most coal bodies are primary structures with developed cleavage cracks. The permeability of coal seam measured by injection/pressure drop method is 0.02~0.40mD, the maximum reservoir pressure is 8.2MPa (vertical depth is 950m), the reservoir pressure gradient is 0.7 ~ 0.9 MPa/ 100 m, the average Langmuir volume is about 23.3m3/t, and the average Langmuir pressure is 2.7MPa.
3. Coalbed methane resources
(1) coalbed methane resources
The total resource of coalbed methane in Hegang mining area (production mine and mine under construction) is 83.35× 108m3, and the total recoverable resource of coalbed methane is 2 1.69× 108m3. In the total resources of coalbed methane, the resource consumption is17.10×108m3, accounting for 20.52%. The remaining CBM resources are 66.25× 108m3, accounting for 79.48%. The consumption of coalbed methane resources consists of two parts: drainage consumption and exhaust consumption. The drainage consumption is about1.61×108m3, accounting for 9.42%; The exhaust air consumption is 15.49× 108m3, accounting for 90.58%. The remaining recoverable resources of coalbed methane are17.19×108m3. The remaining coalbed methane resources in goaf are 5.2 1× 108m3.
(2) CBM resource categories
The eight statistical mine resource categories in Hegang Mining Area are all Class II (Table 7-5), and the evaluation score of mine coalbed methane resources is 170 ~ 180.