Table 8-7 Data Table for Optimization of Favorable Target Area for CBM Exploration
(1) Jincheng area in the south of Qinshui basin
1. Basic overview and exploration and development status
Jincheng area is located in the southern slope belt, which spans Jincheng, Gaoping, Yangcheng, Anze and other counties and cities. The overall structural form is a gentle monocline inclined to the northwest. The main exploration targets are Shanxi Formation 3 coal and Taiyuan Formation 15 coal, with a favorable exploration area of 3260km2 and coalbed methane resources of 84 10× 108 m3, and accumulated proven coalbed methane geological reserves.
Jincheng area is the best high-yield enrichment area of coalbed methane in China at present, forming the first high-rank coalbed methane field in the world. By the end of 2009, * * * has drilled more than 3,000 wells, with an annual gas production of 9.7× 108m3, and the average daily output of a single well is 800 ~ 10000m3.
2. Conditions of coalbed methane accumulation
The coal seam in Jincheng area has a high degree of metamorphism, RO: 2.6% ~ 3.8%, gas content is generally high, generally 15 ~ 24m3/t, and gas saturation is 56.4 1% ~ 100%.
The buried depth of main coal seams in this area is between 150 ~ 1300m, and the thickness is generally 5 ~ 7m. The roof of coal seam is mostly mudstone and silty mudstone, which has strong sealing ability and is beneficial to the preservation of coalbed methane.
The total salinity of groundwater in the main coal seam is 800 ~ 2600 mg/L, and the main hydrochemical type is NaHCO3. The groundwater runoff condition is weak, and the groundwater retention area has slow runoff, which is a favorable accumulation area for coalbed methane.
(2) Jixian-Hancheng area on the southeast edge of Ordos Basin.
1. Basic overview and exploration and development status
Daning-Hancheng area in the eastern margin of Ordos basin has become one of the hot spots of coalbed methane exploration and development in China. There are 6030.4× 108m3 coalbed methane resources in Daning-Jixian block, and the abundance of coalbed methane resources is 1.78× 108m3/km2. The coalbed methane resource in Hancheng-Heyang block is 2850.6× 108m3, and the coalbed methane resource abundance is1.46x108m3/km2 (Table 8-8).
Table 8-8 Statistics of CBM Resources with Different Buried Depth in Daning-Hancheng Area
The proven geological reserves of coalbed methane in Hancheng area are 5 1× 108 m3 and 3.6× 108m3 in Banqiao area. By the end of 2009, more than 300 coalbed methane wells have been built in this area, and the annual gas production in Hancheng area is 1500× 104m3.
2. Conditions of coalbed methane accumulation
The main minable coal seams in Daning-Hancheng area are No.5 and No.8 coal seams, and the thickness of coal seams is generally 3 ~ 5m. The gas content of No.5 coal is between 3.19 and 20.87m3/t, with an average of15.25m3/t; The gas content of No.8 coal is mostly between 3.09 ~ 17.2m3/t, with an average of10.31m3/t. ..
The metamorphic degree of coal in this area is high, mainly coking coal, lean coal and lean coal, and the western part of the study area can reach anthracite. The vitrinite content of No.5 main coal and No.8 main coal in this area is 64.2% and 64.0%, among which the vitrinite content in Daning-Jixian area is slightly higher than that in Hancheng-Heyang area. The permeability of the two main coal seams is between (0.1~ 6.65) ×10-3 μ m2.
The hydrogeological conditions in this area are simple. The aquifer in this area is weak in water abundance and the hydraulic connection between aquifers is poor. Groundwater collects from the outcrop area of eastern coal measures to the deep, forming a coalbed methane enrichment area with high reservoir pressure.
(3) The Sanjiao-Shilou North on the eastern edge of Ordos.
1. Basic overview and exploration and development status
Sanjiao-Shiloubei area is located in the middle of the eastern margin of Ordos Basin, and the structural position is located in the Lishi nose-shaped structural belt. The main development target layers are No.5 coal of Shanxi Formation and No.8 coal of Taiyuan Formation. This area is rich in coalbed methane resources and has a good prospect for coalbed methane exploration. The favorable gas-bearing area is 15 1 1km2, and the coalbed methane resource is 2749× 108m3. Among them, the shallow favorable area of No.5 coal seam151km2, and the resource amount1667m3; ; No.8 coal 1500m shallow favorable area 1270km2, and resource amount 1082m3.
By the end of 2009, * * CBM wells 129 were under construction. Sanjiao and Liulin blocks are hot spots of coalbed methane development at present, and the proven reserves in the northern part of Liulin block have been submitted to 53× 108m3.
2. Conditions of coalbed methane accumulation
The metamorphic degree of coal and rock is increasing from north to south, and it is generally fat coking coal. The total thickness of coal seam is 10~20m ~ 20m, showing the distribution characteristics of thick in the north and thin in the south. The thickness of No.5 coal seam is 0 ~ 7m, that of No.8 coal seam is 2 ~ 15m, and that of most areas west of the eastern outcrop area is about 5 ~ 10m. The gas content of No.5 coal seam is distributed in the east-west belt, and the gas content near the outcrop area in the east is low (0 ~ 5m3/t), and the gas content in the west gradually increases with the increase of buried depth (15 ~ 20m3/t). No 8 coal seam has the same distribution characteristics. The gas saturation of No.5 coal is generally higher than that of No.8 coal.
The top rock type of No.5 coal seam is mainly mudstone. Mudstone caprock is widely distributed in the work area with a thickness of 0.5~40m. The top rock type of No.8 coal is mainly limestone.
The porosity of coal and rock in this area is generally 3% ~ 8% (Table 8-9). Cleavage and cracks are developed in Sanjiao-Liulin area with good permeability. The poor permeability in Shilou and Wubao areas is mainly related to the large buried depth of coal seam.
Table 8-9 Statistics of Porosity and Permeability of Coal and Rock in Work Area
(D) Fuxin Basin, Liaoning Province
1. Basic overview and exploration and development status
Fuxin basin is located in the west of Liaoning province, with Songling Mountain range in the west and Yiwulu Mountain range in the east, which is a long and narrow belt valley distributed in the northeast. The stratum is generally monoclinic structure, and the dip angle of stratum is between10 ~ 20.
Fuxin coal-bearing stratum is the Lower Cretaceous Fuxin Formation in Mesozoic, with a high gas mining area of 27.62km2, coalbed methane reserves in the unexploited area of No.3 Mine of 70.68× 108m3, mined-out area of No.3 Mine of 23.62× 108m3 and total coalbed methane reserves of No.3 Mine of 94.30× 65438. The gas production in 2009 was about 3000× 104m3.
2. Conditions of coalbed methane accumulation
Liu Jia-Wangyingqu jointly developed Himalayan diabase. The intrusion of magma promotes the formation of coalbed methane, increases the porosity and permeability of coal seam, and provides a good storage space for coalbed methane.
The type of coal and rock is mainly long-flame coal, with a small amount of gas coal in the deep, with a total thickness of 30 ~ 100 m and a buried depth of 300 ~1000 m. The coalbed methane content of coal reservoir is (8.42 ~ 12.6) m3/t, which is generally 9.5m3/t ... The coal seam permeability is (0.323 ~ 0.469) × 10-3 μ m2.
Table 8- 10 Calculation Table of Coalbed Methane Reserves
(5) Daxing Minefield in Tiefa Coalfield, Liaoning Province
1. Basic overview and exploration and development status
Tiefa Coalfield is located 34km northwest of Tieling City, with a length of 29.5km from north to south, a width of 17.4km from east to west and an area of about 5 13km2. Daxing mine field is a syncline structure extending to the northeast, with gentle north wing and steep south wing, and the coalbed methane resource is 92.77× 108m3.
Daxing mine field in Tiefa coalfield has the characteristics of good resource conditions, high resource abundance, clear reservoir characteristics and broad market for coalbed methane utilization, and has a good prospect for coalbed methane development. From 1996 to 2008, there were 13 production test wells of coalbed methane parameters in Daxing well field of Tiefa coalfield.
2. Conditions of coalbed methane accumulation
Magmatic activity in Daxing mine field is intense, including eruption and intrusion. Eruptive rocks are mainly basalt and intrusive rocks are mainly diabase (Figure 8-4). Both magmatic rocks intrude into coal measures, which has great influence on coal measures, especially the main coal seam, and increases the content of coalbed methane, which is beneficial to the production of coalbed methane.
Daxing mine field * * has 14 minable seam. The eastern coal seam is thin and gradually thickens to the west. There are two coal collection centers in the west of the mine field. The thickness of coal seam is generally 3 ~ 20m, the buried depth is 550~650m, the gas content is 2.43 ~ 8.18m3/t. The permeability is between (0.01~1.507) ×10-3 μ m2.
Figure 8-4 Relationship between Diabase, Coal Seam and Structure in Daxing Mine Field
(6) Yangquan area in the north of Qinshui basin.
1. Basic overview and exploration and development status
Yangquan mining area is located in the northeast corner of Qinshui coalfield, which spans Yangquan City, Pingding and Xiyang in Jinzhong area. The favorable exploration area is 360km2, and the coalbed methane resource is 944× 108m3. By the end of 2009, more than 330 CBM wells have been drilled, with a daily gas production of 3.2× 104m3. Yangquan mining area is 364km2, and the remaining coalbed methane resources are 944× 108m3.
2. Conditions of coalbed methane accumulation
The buried depth of the main coal seam is 300 ~ 800 m, the gas content is 8 ~ 103/t, the average thickness of No.3 coal in Shanxi Formation and No.5 coal in Taiyuan Formation is 1.35m, and the thickness of No.5 coal in 15 is 5.20m, indicating that anthracite is the main coal evolution degree. The methane content in No.3 coal seam is between 0.82 ~ 16.80m3/t, with an average of 8.23m3/t; 15 coal seam methane content is between 0.49 ~ 9.92m3/t, with an average of 4.24m3/t; No.3 coal seam is mainly sandy mudstone with a thickness of 2 ~ 9m 15 coal seam with a thickness of 3 ~1m. The maximum permeability of coal seam is 13.36× 10-3μm2.
(7) Baode-Shenmu area in the northeast of Ordos Basin.
1. Basic overview and exploration and development status
The study area is located in the eastern and northern part of Ordos basin, which spans two major structural units: Shanxi Flexural Zone and Yishan Slope. The study area includes Shenmu County and Fugu County in Shaanxi Province, Hequ County and Baode County in Shaanxi Province. The best area for coalbed methane exploration is located in Baode-Sunjiagou area on the east bank of the Yellow River. The buried depth of No.5 and No.8 coal seams in this area is 300 ~1500m, with a total area of 2098km2. The total coalbed methane resources are 3453.8× 108m3, and the average resource abundance is1.65x108m3/km2 (Figure 8-5).
By the end of 2009, 4 CBM wells 150m3 have been drilled in Baode, including 4 U-shaped horizontal wells, with a maximum daily gas production of 6000m3 and an average daily water production of150m3.
2. Conditions of coalbed methane accumulation
Long flame coal, gas coal, fat coal and coking coal are developed in this area. From north to south, the coal rank gradually rises, showing the characteristics of strip distribution, and the Ro is 0.7% ~ 1.2%. The total thickness of coal seam is 10 ~ 35m, and the single thickness of main coal seam is 8 ~ 10~35m, showing the distribution characteristics of thick east and west sides and thin north and south parts. Buried deeply controlled by structure, generally shallow in the east and deep in the west. The buried depth of No.5 coal seam is between 0 and 2000 meters, and the plane distribution of the buried depth of No.8 coal seam is the same as that of No.5 coal seam. At the same well point or place, the buried depth is only 30 to 60 meters deeper than that of No.5 coal seam.
Figure 8-5 Comprehensive Evaluation Map of Coalbed Methane in Baode-Shenmu Area
The gas content of No.5 coal is 5.7 1 ~ 9.7 1m3/t, with an average gas content of 8.35m3/t; The gas content of No.8 coal is 8.23 ~19.95m3/t, and the average gas content is13.9m3/t. ..
The lithology of No.5 coal roof in this area is mostly mudstone, which is beneficial to the preservation of coalbed methane. However, sandstone caprocks are developed in some areas of No.8 coal roof, which is not conducive to the preservation of coalbed methane. The porosity of No.5 coal and No.8 coal is between 6.9% and 9.33%, which are medium and high porosity coal seams. The permeability is between (1 ~ 5) × 10-3μ m2, which is a mesoporous permeable layer. Both main coal layers have the characteristics of medium and high porosity and permeability, and with the increase of coal seam buried depth, the porosity and permeability conditions tend to deteriorate.
(VIII) Southern area of Ningwu Basin
1. Basic overview and exploration and development status
Ningwu Basin is located in the northwest of Shanxi Province, with Luliangshan uplift and Luyashan anticlinorium in the west and Wutaishan uplift in the east. It is a tectonic basin formed by tectonic movement after the late Paleozoic coal-forming period, with an area of about 365,438 0.20km2.. No.4 coal at the bottom of Shanxi Formation and No.9 coal at the bottom of Taiyuan Formation are the main target beds for exploration.
At present, two CBM wells 12 have been drilled in this area, and the maximum daily gas production of three CBM wells exceeds 1000m3, which proves that the southern part of Ningwu basin has good CBM exploration potential. It is predicted that the favorable exploration area of No.9 coal in Taiyuan Formation is 534km2, which contains shallow coalbed methane and its geological resources 1500m 108m3. After exploration, the gas-bearing area of No.9 coal in Taiyuan Formation in this area is initially controlled at112.15km2; The controlled reserves of coalbed methane are191.32×108m3 (Figure 8-6).
Figure 8-6 Comprehensive Map of Controlled Reserves of No.9 Coal in the South of Ningwu Taiyuan Formation
2. Conditions of coalbed methane accumulation
The coal rank in this area is low to medium metamorphic gas-rich coal, and the Ro is 0.85% ~ 1. 12%. The evolution degree of No.4 coal in Shanxi Formation is slightly lower than that of No.9 coal in Taiyuan Formation. The buried depth of coal seam is mainly controlled by structure and topography, and the change law is simple. The buried depth of coal seam in favorable area is 500 ~1500m. The thickness of No.9 coal is 4.36~24.62m, and the average thickness exceeds11m. The thickness of No.4 coal is 0.37 ~ 13. 15m, generally 2 ~ 4m. The gas content of No.4 coal in Shanxi Formation is generally 2 ~ 6m3/t, and that of No.9 coal in Taiyuan Formation is generally 5 ~ 65438+1100m3/t. The porosity of coal seam is 3.97% ~ 5.2%, and the permeability is generally (0.01~ 0.86) ×/kloc-0.
The direct roof of No.4 coal in Shanxi Formation in the south of Ningwu Basin is dominated by shale, sandstone and siltstone, while the roof of No.9 coal in Taiyuan Formation is dominated by marl and mudstone, with a small amount of limestone and sandstone.
(9) Huolinhe area in Erlian basin
1. Basic overview and exploration and development status
Huolinhe Basin is located in the southern section of Daxinganling, 400 kilometers northwest of Tongliao City. It is a semi-graben fault basin with northeast distribution. The upper Jurassic-lower Cretaceous Huolinhe Formation is the coal-bearing section in this area, and the lower coal-bearing section of the upper Jurassic is the key target layer for coalbed methane exploration in this area. The basin covers an area of 540km2, of which the favorable gas-bearing area is 380km2, and the coalbed methane resource is 1008× 108m3 (Table 8- 1 1). In 2007, China Petroleum drilled a coalbed methane well in the central depression, and obtained industrial gas flow through drainage test, which revealed that this area has a good prospect for coalbed methane exploration.
Table 8- Calculation Table of CBM Resources in Huolinhe Basin +0 1
2. Conditions of coalbed methane accumulation
Ro of coal seams in this area is between 0.370% and 0.603%, generally lower than 0.5%, mainly lignite. The thickness of coal seam is huge, and the average total thickness of minable coal seam is 76.91m.
The buried depth of coal seams in Huolinhe area is mostly shallower than 1000 m, and the buried depth of methane weathering zone is about 400 m.
The gas content is 2.08 ~ 6.53m3/t, and the average methane content in coal seam is 9 1.47%. The coal seam porosity in this area is high, and the average porosity of the lower coal-bearing section is 17.9%. The measured permeability of 900m coal seam is 0.9 1× 10-3μm2, and the overall physical properties of coal reservoirs in this area are good, and the permeability of shallow coal seams will be higher.
The lithology of the direct roof and floor of the main coal seam is mostly argillaceous or tuffaceous cemented mudstone and siltstone, which has good sealing property. The coal-bearing aquifer is in confined water environment, which is beneficial to the closed preservation of coalbed methane.