六盘水松沙地区煤层气地质特征及勘探潜力分析

CBM Geological Features and Exploration Potential Analysis in Songsha Region,Lupanshui

通过对六盘水松沙地区煤层特征、煤岩煤质、煤变质程度、孔渗、等温吸附、煤岩力学特征、煤层含气性、生气及保存条件及该区煤层气勘探前景分析,结果表明:松沙地区含煤地层主要为龙潭组,含煤28～49层,总厚24. 78m;显微煤岩组分以镜质组为主,高达60. 72%～75. 05%,煤层镜煤反射率(Ro,max%)为0. 85%～1. 06%,为中等变质程度,整体属于气-肥煤,为煤层气的形成奠定了物质基础;煤层宏观裂隙发育,连通性好,孔隙结构以小孔和微孔为主,透气性较好,有利于煤层气的吸附;研究区主要可采煤层含气量较高,为3. 30～17. 32m3/t;主要煤层兰氏体积为4. 35～14. 71m3/t,平均8. 1m3/t;煤层顶底板岩性抗压强度、抗拉强度比煤层大。煤系地层水动力条件弱,水文地质条件简单,煤层顶底板一般为较厚的泥岩和粉砂质泥岩,有利于煤层气的保存与富集成藏。综上分析认为,松沙勘查区具有较好的煤层气勘探开发潜力。

Through studies on coal seam features,coal petrology and coal quality,coal metamorphic degree,pores permeability,isothermal adsorption,coal and rock mechanical features,coal gas-bearing property,gas generation and preservation conditions,as well as CBM exploration prospect in the Songsha region,Lupanshui,the results have shown that the coal-bearing strata mainly belong to the Longtan Formation with 28~49 coal seams,total thickness 24.78m.Macerals have mainly vitrinite,with proportion 60.72%~75.05%as high;reflectance of vitrinite(Ro max%)between 0.85%~1.06%,medium metamorphism degree,belong to gas-fat coal as a whole,thus have laid the material foundation for CBM formation.Macroscopic fissures in coal seam are well developed with good connectivity;pore structures have mainly small pores and micropores with better gas permeability,propitious to CBM adsorption.Main mineable coal seams in study area have higher gas content of 3.30~17.32m^3/t;Langmuir’s volume 4.35~14.71m^3/t,average 8.1m^3/t;compressive and tensile strengths of coal roof and floor rocks are larger than those of coal seams.Hydrodynamic condition of coal measures strata is weak,hydrogeological condition simple,coal roof and floor rocks are generally rather thick mudstone and silty mudstone,thus in favor of CBM preservation and enriched reservoiring.Summed up above analyses,considered that the Songsha exploration area has better CBM exploration and exploitation potential.