| The coal seam is typically high order tectonic fracture of coal in Henan Jiaozuo Mine Group, the horizon average tons of coal containing gas is 10.98 m3 / t, the early stage of the ground in the mining area and the surrounding have caopleted 50 for fracturing and drilling CBM extraction, but due to geological, drilling, fracturing, mining technology lag behind, have all failed, single well’s highest capacity is less than 1000 m3 / dThe technologies about drilling well on the ground for co al bed gas have made a breakthrough in the area of primary structure coal. O ur country has not been achieved significant results in the tectonic coal area, even if we has been tried to drill vertical well and use conventional fracturing many times. The Lower Permian Shang Xi group Ⅱ1 coal seam in the Jiaozuo ZhongMa mine in Henan province is characterized by high rank structure coal. The mining area and its surrounding has accomplished the 50 wells fracturing and drilling for extracting coal bed methane. In China, we firstly put for ward the “Assist-seam”to explore coal bed gas based on the “release-seam”in the mining coal industry and included its mechanism. It’s the first to arrange U-well in the roof of Ⅱ1 coal seam and complete successfully the horizontal well drilling,staged fracturing and U-well production. This project for the domestic development of coal-bed methane in tectonic coal provides a new thought and method.In the implementation of the project for the drilling, first drill a vertical well, drilling to coal floor, the following completion casing, cementing. Under the roof of coal seam in a phi 177.8 mm glass fiber reinforced plastic casing, cementing, coagulation and amplitude measurement, the glass fiber reinforced plastic casing made a about 7 meters long, vertical Wells 400 mm hole, reduce the difficulty of docking. Then drill a horizontal well, the first pilot Wells, dangling after directional sidetracking. Horizontal interval, the RMRS rotary steering technology is used and LWD logging with drilling technology, with reference to coal mining working face transportation lane profile geological map, according to the power tool for resistivity and natural gamma curve, the drilling tool deflection Angle adjustment, ensure that the horizontal well trajectory within about 5 m above the top of the coal seam and sandstone. After the success of the docking, vertical Wells with gravel filling, concrete block, guarantee level of downhole casing, cementing, perforating and fracturing is completed.Due to the level of embedded depth is less than 500 meters, the traditional communication was difficult to form the vertical hydraulic fracturing cracks of coal seam and roof, studies the directional jet fracturing technology can well solve the deep vertical crack problem. At the same time, the hydraulic jet fracturing can implement a single pass string perforating and fracturing operation and drag the staged fracturing string, improve working efficiency.In full on the basis of summarizing the failures in the region, draw lessons from other successful development case, study and formulate a row of four phase control scheme. Using coal-bed methane intelligent mining equipment instead of pumping unit, the traditional equipment such as electric submersible pump, to achieve fine line, guarante e the stability of coal seam drainage, coal seam pressure continuous, slow down, to prevent coal seam caused by excessive drainage and agitate, pulverized coal blocking channels. |
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