本文以彬长矿区大佛寺煤矿侏罗系延安组低阶煤为研究对象，在详细收集研究区的地质勘探资料、矿井瓦斯资料及地面煤层气井资料基础上，采用室内测试分析、编图分析、相关分析、储层数值模拟技术；以天然气地质学、煤田地质学、构造地质学、煤层气地质学及数学地质等理论为指导，对主要可采煤层的地质特征、物性特征、储层气含量主控因素、开采选区影响因素及煤层气产能建模等进行了研究： ⑴大佛寺井田主要可采煤层孔径分布范围广，以中渗透率储层为主，吸附性能中等，含气饱和度较低，临界解吸压力平均1.00～1.13MPa，储层甲烷浓度在50%～80%左右，空气干燥基甲烷含量为1.00～5.57m3/t。 ⑵含气量在井田变化较大，影响煤层含气量的主要控制因素为煤层顶板5m内泥岩厚度与煤层顶面到直罗组顶面砂泥岩比，次为地质构造；依据煤层厚度变化率与褶曲构造叠加复合特点两个指标，参考煤层顶板岩性的变化，对井田可采煤层断层发育程度进行预测，4上煤层中小断层主要发育在煤层厚度变化率在＋0.3以上或－0.30以下范围，4号煤层中小断层主要发育在煤层厚度变化率在＋0.10以上或－0.10以下范围。 ⑶通过对煤储层的孔隙特征、渗透性特征、渗透率特征、吸附——解吸特征、煤层气成分及瓦斯分带、煤层含气量特征的研究，分别对4煤渗透率、储层压力、含气饱和度进行了预测：4煤渗透率总体具有东部高，并由东向西降低的规律；4煤储层压力在井田范围内含气饱和度从西部向东部逐渐增大，4煤含气饱和度在13.92%～97.49%之间，平均为51.42%，表明研究区存在含气饱和度高值区。 ⑷通过水化学特征对比分析，得出地面煤层气井的排采水主要来自距离煤层顶板很近的4上煤～4煤间砂岩含水层水；在分析影响井田低煤阶煤层气开发主要地质因素的基础上，采用加权综合指数法对煤层气有利开发区进行了评价与圈定，得出本区主采煤层以中等有利开发区与不利开发区为主； ⑸运用simediwn软件，对煤层气井产气、产水进行模拟预测，再将模拟结果与生产数据拟合，拟合结果表明，产水曲线和产气曲线总体拟合良好，说明参数选取合适。 研究成果为本区煤层气高效开发提供了依据。

This paper takes the low-rank coal in Dafosi Coal Mine of Binchang, which belongs to the Yan’an formation of Jurassic system, as its researching object. The information collection of geological prospecting、firedamp and ground coal-bed gas well of the object served as its researching preparation；Guided by theories like natural gas geology、coal geology、 structural geology、coal-bed gas geology and mathematical geology, the paper explores the geologic feature、physical characteristics、main controlling factors of reservoir gas content、factors affecting the location of mining district and modeling of coal-bed productivity, etc cetera, of the major minable coal seams, by using indoor test analysis、mapping analysis、correlation analysis、technique of numerical simulation for reservoir. The research shows: (1)The major minable coal seams of Dafosi Field has a large pore size distribution range, with main reservoir of secondary permeability. The seam has a medium adsorptive property, relatively low gas saturation, which belongs to undersaturation, an average critical desorption pressure ranging 1.00～ 1.13Mpa, concentration of methane in reservoir always rounding 50%～80%, methane content measured against air dry basis ranging 1.00～5.57m3/t, and wide range ability of gas content in the field; (2)The main controlling factor of coal-bed analysis is the ratio of thickness of mudstone within 5m to the seam roof to the distance between the seam surface and Zhiluo Formation. The secondary factor is geological structure; Judging from the changing rate of thickness of the seam and the features of the superposition and recombination of folds and structures, this paper makes prediction on the degree of fault development of minable seam in the field with resort to the lithologic changing of roof the seam; in the coal seam thickness change rate are mainly developed 4上coal above ＋0.3 or below －0.30, 4 coal above ＋0.10 or below －0.10. (3) Through the studies on the coal reservoir pore characteristics、Permeability characteristics、permeability、adsorption desorption characteristics of coalbed gas composition、gas zone and the characteristics of coal seam gas content, the paper does prediction of 4coal permeability、reservoir pressure、gas saturation has carried on the forecast: 4 coal has a high penetration rate in the east ,and lower east to west by the low; 4 coal reservoir pressure in the range of mining field contains gas saturation is gradually increasing from the west to the east, 4 coal containing gas saturation between 13.92% ~ 13.92%, with an of average 51.42%, indicating the presence of high gas saturation in the study area value of the area.show that high gas saturation value area in the study area. (4) By means of the contrastive analysis of hydrochemical characteristics, the researcher concludes that the major resource of the water extraction and draining of the ground coal-bed gas well is the aquifer in sandstone 4上 to 4 coal which is quite close to the roof; Based on the analysis of major geological influencing factors of the low-rank coal in the field, the researcher does valuation and delineation for favorable development zone of coal-bed gas. By means of weighted aggregate index number, it comes out that the coal seams in this diggings are medium favorable and unfavorable ones for the most part; (5)Resorting to the simediwn modeling software, the paper gives analytical prediction of the gas yield and production water of the coal-bed gas well;Then the simulation results and production data fitting, the fitting results show that the water production generally fitting curve and the curve of gas is good , selecting an appropriate description of the parameters.Whose findings provides gist for the high efficient development of the diggings.