Thin interbedded coal-measure gas (CMG) reservoirs with marine–continental transitional facies have particularities, and the optimization of the production layer is a critical component of their successful development. Parameters from seven Late Permian CMG wells (i.e., geochemical, reservoir physical characteristics, and gas-bearing test data) in the north end of Tucheng Syncline in western Guizhou were collected. Combined with regional geological data, the development characteristics, geochemical characteristics, reservoir porosity, permeability characteristics, and gas-bearing characteristics of CMG in the thin interbedded Longtan Formation of marine–continental transitional facies were analyzed systematically. Then, four geological characteristics of the thin interbedded CMG reservoir of the Longtan Formation of the marine–continental transitional facies were defined as follows. (1) The sedimentary environment of coal measures in marine–continental transitional facies changes frequently; coal, shale and sandstone are interbedded frequently; and the thickness of each type of reservoir varies greatly, but the cumulative result is thick. (2) Mud shale and sandstone in coal-measure strata have high TOC and similar R_O, and shale and sandstone have similar inorganic content, showing the characteristics of high clay and low brittleness, and sandstone showing obvious shale characteristics. (3) The coal seams have a significant gas concentration and are the foundation of CMG resources. The gas content in shale is unevenly distributed. Some carbonaceous mudstone is close to the coal seam, and the gas content of sandstone is the lowest. The gas content of sandstone and mudstone has a certain correlation with the distance from the coal seam. Within 1 m from the coal seam, the gas content of sandstone and mudstone in coal measures is generally higher than 1 m³/t. (4) The coal measure reservoir has low porosity and permeability, so industrial gas flow can be obtained only through engineering transformation. Based on these geological characteristics and on the “three-step” optimization combination of multicoal seam production layers and principal components analysis of non-coal measure reservoir physical properties, a "four-step" optimization of coal measure reservoir combined production sections was established. Taking well PC-1 as representative of the spatial relationship between the target coal seam and sandstone layer, three sets of CMG combined production combinations were optimized.

海陆过渡相薄互层煤系气藏具有特殊性，产层优化是其成功开发的关键。采集了黔西土城向斜北端7口晚二叠世CMG井的地球化学、储层物性、含气试验数据等参数。结合区域地质资料，系统分析了海陆过渡相薄互层龙潭组CMG的发育特征、地球化学特征、储层孔隙度、渗透率特征和含气特征。然后，海陆过渡相龙潭组薄互层CMG储层4个地质特征定义如下。(1) 海陆过渡相煤系沉积环境变化频繁；煤、页岩、砂岩频繁互层；各类型储层厚度差异较大，但累积结果较厚。(2) 煤系地层中的泥页岩和砂岩具有较高的 TOC 及相似性R _O，与页岩和砂岩无机含量相近，呈现高粘土低脆性特征，砂岩表现出明显的页岩特征。（3）煤层瓦斯浓度高，是煤层气资源的基础。页岩中的含气量分布不均。一些碳质泥岩靠近煤层，砂岩含气量最低。砂岩、泥岩的含气量与距煤层的距离有一定的相关性。距煤层1 m以内，煤系砂岩、泥岩含气量一般高于1 m ³/吨。(4)煤系储层孔隙度和渗透率低，只有通过工程改造才能获得工业气流。基于这些地质特征，在多煤层产层“三步”优化组合和非煤系储层物性主成分分析的基础上，建立了煤系储层组合生产段“四步”优化。以PC-1井为代表目标煤层与砂岩层的空间关系，优化了3套CMG联合生产组合。