低阶煤煤层气富集区预测方法研究与应用

Research and application of the prediction method for CBM enrichment area of low rank coal

目前低阶煤煤层气勘探面临资源探明率低,单井产量低的问题,中、低阶煤煤层气勘探还处于摸索阶段。为提高低阶煤煤层气富集区预测精度,探索性应用"弹性模量参数反演技术"。应用韩城、晋城、保德、吉尔嘎朗图、沁水盆地、淮南、淮北等地56口井652个煤样实验室测试数据,进行高、中、低阶煤含气量与弹性参量关系对比分析,结果表明:不同煤阶的煤层含气量与弹性参量之间相关关系具有一致性,且密度对低阶煤含气量的变化较中、高阶煤更为敏感,认为低阶煤煤层气储层具有利用地球物理方法进行识别的基础。在此基础上,选取吉尔嘎朗图凹陷三维地震数据,应用叠前弹性模量参数反演方法,预测其白垩系下统赛罕塔拉组Ⅳ煤组煤层气富集区面积总计101 km^(2),为下一步开发提供了优质建产区;经验证,预测结果与含气量测试结果吻合率为83.3%。叠前弹性模量参数反演可应用于低阶煤煤层气富集区预测,研究结果对低阶煤煤层气勘探开发具有一定的指导意义。

The exploration of low rank coal coalbed methane(CBM) faces the problems of low resource exploration rate and low single well production. And medium and low rank coal CBM exploration is still in the primary stage.In order to improve the predition accuracy of the low rank coal CBM enrichment area, the laboratory test data of 652 coal samples from 56 wells in Hancheng, Jincheng Baode, Ji’ergalangtu Qinshui Basin, Huainan, Huaibei and other places were collected to compare the relationship between gas content and elastic parameters of high, medium and low rank coal samples. The results indicated that the correlation between coal seam gas content and elastic parameters of different coal rank is consistent. And density is more sensitive to the changes of gas content of low rank coal than that of medium and high rank coal. It is considered that low coal-rank CBM reservoirs have the basis for identification using geophysical methods. On this basis, the 3D seismic data of the Ji’ergalangtu depression was selected and the pre-stack elastic modulus parameter inversion method was applied to predict its coal-bed methane enrichment area in the Ⅳ coal group of the Lower Cretaceous Saihantala Formation with a total area of 101 km;,which provides a high-quality construction area for the next development. The coincidence rate between the predicted results and gas content test results was 83.3%, which further proved that it was feasible to detect the low rank coal CBM enrichment area by prestack elastic parameters inversion of relative change. The research results have certain guiding significance for the exploration and development of low rank coal CBM.