论文部分内容阅读
利用露头、钻井及岩心等资料,以地球化学、储层、气体成因以及构造保存条件等为重点研究对象,对湖南省常德地区牛蹄塘组页岩气的成藏条件开展了系统分析。研究表明:该区域牛蹄塘组富有机质页岩具有机碳含量高、厚度大、热演化程度普遍较高的特点;页岩的有效孔隙度为2%~5%,储集空间主要以基质孔隙为主,朗格缪尔体积分布于1~3.5m~3/t之间;盖层厚度较大(>200m),具备形成页岩气的生、储、盖条件。分析了常德1井产水产气的原因,指出所产气、水主要产自牛蹄塘组底部富有机质页岩中的封闭裂缝体系中,处于地层水交替阻滞带,所产烃类气体主要为原油裂解气,非烃类气体主要为过成熟阶段产物,并混入了部分大气,氦气为壳源无机成因。明确了常德地区页岩气成藏过程及散失模式,认为构造破坏、地层水散失和扩散作用是页岩气散失的主要途径,页岩的含气性主要受构造及保存条件控制。优选常德1井以西(地层水交替阻滞带以下)保存条件较好的区域为页岩气分布的有利区,具有较大的资源潜力。
Based on the data of outcrop, drilling and core, the geochemical conditions, reservoir, gas genesis and tectonic preservation conditions are the main research objects. The formation conditions of shale gas in Niutitang Formation in Changde, Hunan Province are systematically analyzed. The results show that the organic-rich shale in Niutitang Formation in this area is characterized by high carbon content, large thickness and high thermal evolution. The effective porosity of shale is 2% ~ 5% Porosity, and Langmuir volume distributed between 1 ~ 3.5m ~ 3 / t. The thickness of caprock is larger (> 200m), which has the conditions for the formation, formation and accumulation of shale gas. The reason of producing gas and gas in Changde-1 well was analyzed. It is pointed out that the produced gas and water are mainly produced in the closed fracture system in the organic-rich shale at the bottom of the Niutitang Formation and in the stagnant zone of formation water. The hydrocarbon gas produced mainly For crude oil cracked gas, non-hydrocarbon gas is mainly over-mature stage product, and mixed into the part of the atmosphere, helium as a shell inorganic origin. It is clear that shale gas accumulation process and dissipation model in Changde area suggest that structural failure, formation water dissipation and diffusion are the main ways of shale gas loss. The gas content of shale is mainly controlled by tectonic and preservation conditions. It is preferable that the area with good preservation conditions to the west of Changde-1 well (below the alternate stagnation zone of formation water) is a favorable area for shale gas distribution with great resource potential.