煤炭地下气化地质选址原则与案例评价

21世纪以来,煤炭地下气化技术水平快速发展,以煤层水平井和移动注气技术应用为基础的现代煤炭地下气化技术日益成熟,具备了产业化示范的技术基础。煤炭地下气化的技术流程包括气化炉选址、气化炉建炉、气化炉点火、气化过程测量与控制、地下水污染防治与控制、气化炉闭炉,而地质选址是煤炭地下气化项目规划、规模化稳定生产及地下水污染防治的保障条件和先决条件。首先概述了煤炭地下气化的3种主要技术路线。依据现代煤炭地下气化技术路线,提出了地质选址评价的基本原则。地质选址需从煤炭储量、煤层条件、地质构造、水文地质条件、顶底岩层稳定性、煤种、煤质等多个角度,围绕气化炉建设、稳定气化和环境影响进行全面评价。在此基础上,以内蒙古哈日高毕矿区为例,进行了煤炭地下气化地质选址案例分析。基于三维地震解释成果和波阻抗反演数据体,研究了目的煤层的空间展布及断层发育特征。通过对拟声波反演结果进行分析,获得了目的煤层顶底板岩性的分布特征。基于地震属性和视电阻率测井曲线,采用多属性神经网络反演对目的煤层及顶底板的富水性进行了研究。基于蚂蚁体属性技术对目标层段的裂隙发育特征进行了分析。最后,从煤层展布及构造特征、岩性分布特征、富水情况、裂隙发育规律方面对案例研究区进行了地质选址综合评价,以此作为科学选址的决策依据。

Geological site selection and evaluation for underground coal gasification

The key technology of underground coal gasification (UCG) has rapidly developed since the 21st century.The modern UCG technology based on directional borehole in the coal seam and moveable gas injection is growing mature and is expected to provide the technical basis for UCG commercialization.The technical process of UCG consists of site selection,gasifier construction,ignition,measurement & control,groundwater pollution control & prevention,shut down of gasifier.Geological site selection for UCG is the most important guarantee condition for UCG project plan,stable operation control,and groundwater pollution prevention.In this paper,typical UCG technical routings were outlined.Combined with the modern UCG technology,the basic principles for geological site selection were put forward from the aspects of coal reserves,coal seam conditions,geological structure,hydrogeological conditions,roof and bottom rock stability,coal types and coal property.On this basis,taking the Ha Jigobi mining area in Inner Mongolia as an example,a case study of UCG geological site selection was carried out.Based on the results of 3D seismic interpretation and wave impedance inversion data,the spatial distribution and fault development characteristics of the target coal seam were studied.By analyzing the results of the pseudo acoustic inversion,the distribution characteristics of the lithology of the roof and floor of the target coal seam were obtained.Based on seismic attributes and apparent resistivity log curves,a multi attribute neural network inversion was used to study the water abundance of the target coal seam and the roof and floor.Based on the ant body attribute technique,the fracture development characteristics of the target stratum were analyzed.Finally,the comprehensive evaluation of the geological site selection of the case study area was carried out from the aspects of coal seam distribution and structural characteristics,lithological distribution characteristics,water abundance conditions and fracture development law,which was used as the decision making basis for scientific site selection.