煤炭地下气化(UCG)地质条件评价将极大降低其工程风险，科学选址则是UCG工程能否成功的先决条件。为研究延川南区块深部UCG地质条件评价和优选有利区域，对研究区2号煤层的煤岩煤质、煤层赋存、围岩、水文地质、构造等指标进行量化处理，利用TOPSIS法，对各开发区域进行数学评价和等级划分，最终形成有利区、较有利区以及潜在有利区的综合评价结果。

结果表明：研究区2号煤层属于三角洲平原相沉积环境，大部分属于中煤级煤，焦煤、贫煤和瘦煤均有分布；平均水分和灰分平均含量较低，挥发分产率较高，硫分含量则是从低硫煤到高硫煤都有一定发育；煤层厚度较大，稳定性较好，平均夹矸层数和夹矸系数相对较小，煤层结构简单，属于稳定的中厚−厚煤层，煤体结构较完整。2号煤层的顶底板岩性多为泥岩类，围岩综合岩性指数较大，封闭性能好；总体断层分形维数值中等，断层发育程度简单，开发条件较好；研究区地表水部分发育，水文分形维数值中等，地下水封闭系数较大。

整体而言，研究区2号煤层的资源条件和地质条件适合进行UCG工程实施。依据构造、埋深、河流和矿井边界等分布特征，结合地勘资料描述，将目的煤层划分为11个开发单元，有利区主要集中在北部，最有利区域是中北部的单元Ⅴ和Ⅲ，较有利区主要为Ⅰ、Ⅱ、Ⅳ、Ⅵ、Ⅶ、Ⅸ、Ⅹ，区域Ⅷ和Ⅺ为煤炭地下气化开发的潜在有利区。

Geological condition assessment for underground coal gasification (UCG) allows for considerably reducing the risk of UCG projects, while scientific siting serves as a prerequisite for the success of UCG projects. To achieve the geological condition assessment for deep UCG and the selection of optimal favorable areas in the Yanchuannan block, this study quantified the indices of coal quality, coal seam occurrence, surrounding rocks, hydrogeology, and structures in the No.2 coal seam in the study area. Employing the technique for order preference by similarity to an ideal solution (TOPSIS) method, this study performed mathematical assessments and grading of various exploitation units. Finally, this study obtained comprehensive assessment results of favorable, relatively favorable, and potentially favorable areas for UCG.

The results indicate that the No.2 coal seam in the study area was formed in a sedimentary environment of the delta plain facies. This coal seam consists primarily of medium-rank coals, including coking, lean, and meagre coals, exhibiting low average moisture and low average ash contents and a high yield of volatile constituents. In terms of sulfur content, the No.2 coal seam contains low- to high-sulfur coals. Furthermore, the No.2 coal seam manifests a considerable thickness, high stability, a low average gangue layer number, and low gangue coefficients (i.e., the ratio of the total gangue thickness to the total coal seam thickness), and simple structures, suggesting a stable moderately thick to thick coal seam with a relatively complete coal structure. The roof and floor of the No.2 coal seam are dominated by mudstones, and its surrounding rocks show high values of the comprehensive lithological index and high sealing performance. Faults in the coal seam exhibit moderate fractal dimension values overall, suggesting simple fault development and favorable conditions for exploitation. The study area exhibits surface water locally, with moderate hydrological fractal dimension values and high groundwater sealing coefficients.

Overall, the No.2 coal seam in the study area exhibits resource and geological conditions suitable for the implementation of UCG projects. Based on the distribution characteristics of structures, burial depths, rivers, and mine boundaries, as well as the description of geological exploration data, the No.2 coal seam can be divided into 11 exploitation units, with favorable areas for UCG primarily distributed in the northern part. Specifically, the most favorable areas consist of units Ⅴ and Ⅲ in the north-central part, the relatively favorable areas include units Ⅰ, Ⅱ, Ⅳ, Ⅵ, Ⅶ, Ⅸ, and Ⅹ, and potentially favorable areas comprise units Ⅷ and Ⅺ.