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沁水盆地寿阳西部地区煤层气资源潜力评价

Potential evaluation of coalbed methane resources in western Shouyang County of Qinshui Basin

  • 摘要: 针对寿阳西部地区景尚东区块煤层气赋存情况不明、勘查程度低、资源潜力评价依据不足现状;采用钻探、物探、样品分析测试、等温吸附试验、注入压降试井手段,获得了该区块煤储层的深度、厚度、结构、煤质、含气量、等温吸附性能、孔隙度、渗透率、储层压力、地应力等参数,研究了煤层赋存特征、煤层含气性与吸附特征、煤岩煤质及煤变质特征、储层物性特征、资源开发潜力等。研究结果表明:该区煤层累计厚度大,平均厚度累计9.91 m,煤变质程度高,各煤层含气量高,3、8、15、15下号煤层平均含气量分别为13.69、14.29、9.59、11.82 m3/t,估算煤层气地质资源量为145.13×108 m3,具有很好的资源条件;含气饱和度介于40%~62%,平均50 %,表明本区煤层含气饱和度低;临界解吸压力介于0.65~2.76 MPa,平均1.38 MPa,临界解吸压力低;孔隙度平均4.89%,宏观裂隙发育1~3 条/cm,显微裂隙不发育,孔隙、显微裂隙、宏观裂隙连通性差,渗透率为4.5×10-17 m2,渗透性较差;闭合压力较大,破裂压力与闭合压力差较小;低含气饱和度、低临界解吸压力、低渗透率是未来煤层气开采的不利因素。综合分析认为区块具有进一步勘查开发的潜力。

     

    Abstract: In view of the current situation of unclear coalbed methane occurrence, low exploration level, and insufficient resource potential evaluation basis in Jingshangdong block in the western region of Shouyang, the following parameters of coal beds were obtained, including burial depth, thickness, structure, coal quality, gas content, isothermal adsorption property, porosity, permeability, reservoir pressure and crustal stress. The occurrence characteristics of coal seam, gas bearing capacity and adsorption characteristics, coal petrology and coal metamorphism, coal reservoir characteristics and resource development potential were studied in this paper. The results show that the cumulative thickness of coal seams in this area is large, the average thickness is 9.91 m, the coal metamorphism is high, and the gas content of each coal seam is high with the average gas content of No.3, 8, 15, 15 lower coal bed at 13.69, 14.29, 9.59 and 11.82 m3/t, respectively. The estimated CBM resources is 145.13×108 m3, suggesting good resource conditions. The gas saturation of coal beds are low, ranging from 40% to 62%, with an average of 50%. The critical desorption pressure ranges from 0.65 MPa to 2.76 MPa with an average value of 1.38 MPa. The average porosity is 4.89%, micro-fractures and macro-fractures have poor connectivity, with a permeability of 4.5×10-17 m2,which is very poor. The closing pressure is large, and the difference between the rupture pressure and the closing pressure is small; low gas saturation, low critical desorption pressure, and low permeability are unfavorable factors for future CBM exploitation. The comprehensive analysis shows that the block has the potential for further exploration and development. The comprehensive analysis shows that the block has the potential for further exploration and development.

     

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