浙西南——赣东北地区寒武系荷塘组页岩气成藏地质条件及有利区带优选  

Shale gas reservoir-forming conditions and exploration prospecting in the Cambrian Hetang Formation of southwestern Zhejiang and northeastern Jiangxi Province

作　　者：邵威 黄正清[1] 李建青 周道容 SHAO Wei;HUANG Zhengqing;LI Jianqing;ZHOU Daorong(Nanjing Center,China Geological Survey,Nanjing 210016,Jiangsu,China)

机构地区：[1]中国地质调查局南京地质调查中心,江苏南京210016

出　　处：《中国地质》2022年第4期1262-1274,共13页Geology in China

基　　金：中国地质调查局项目“下扬子地区寒武系页岩地球化学特征与含气性研究”(2016ZX05034001-003)资助。

摘　　要：【研究目的】浙西南—赣东北地区寒武系荷塘组广泛发育暗色泥页岩,是下扬子地区页岩气调查的重点层位。目前该区勘探程度低,导致对该区页岩气成藏条件认识不清。【研究方法】通过寒武系荷塘组暗色泥页岩发育的地质背景、有机地球化学参数以及野外调查等方面研究,对该区页岩气资源潜力进行了评价,对有利区进行了优选。【研究结果】浙西南—赣东北地区寒武系荷塘组炭质硅质页岩在研究区内分布广泛,沉积厚度达35~200 m,其中在开化—常山—玉山地区的平均厚度超过50 m;有机质丰度高(1.48%~23.53%),镜质体反射率适中(2.01%~3.0%),有机质处于成熟—过成熟阶段。研究区荷塘组地层发育微孔隙、微裂缝等孔隙类型,储集性能较好。等温吸附实验测得炭质硅质页岩吸附气含量平均为5.93 kg/t,表明荷塘组炭质硅质页岩具有较好的吸附能力,有一定的吸附性。【结论】以在高热演化程度环境中找热演化程度较低的区域和在复杂的构造背景中寻找相对稳定的区域为准则,研究认为开化—常山—玉山地区寒武系荷塘组炭质硅质页岩分布厚度适中,有机质丰度高,成熟度相对较低,页岩气保存地质条件较好。[Objective]The dark shale of the Cambrian Hetang Formation widely occurred in southwestern Zhejiang and northeastern Jiangxi is the key target of shale gas exploration in the Lower Yangtze region.However,due to the present low exploration level of this interval,understanding of the shale gas accumulation conditions is still insufficient.[Methods]Based on the analysis of geological background,organic geochemical indicators and field stratigraphic outcrop investigation of the dark shale,the shale gas resource potential is evaluated and the favorable areas are optimized.[Results]The dark shale ranges from 35 to 200 meters in thickness with an average of over 50 meters in Jiangshan-Changshan area and is characterized by medium to high content of organic matter(TOC ranging from 1.48%to 23.53%)and high to over maturity(Ro ranging from 2.01%to 3.0%).The organic matters are highly and over highly matured.Abundant micropores and microfractures were observed in the shales,indicating the high quality shale reservoirs.The isothermal adsorption experiment shows that the carbonaceous shale has strong adsorption ability,which reaches 5.93 kg/t on average.[Conclusions]It is suggested that the region of Jiangshan-Changshan area in western Zhejiang is favorable for shale gas exploration on the basis of relatively low thermal evolution of organic matter and stable stratigraphic structure preservation conditions.

关 键 词：页岩气 成藏条件 荷塘组 油气勘查工程 常山 浙江 江西 

分 类 号：P618.13[天文地球—矿床学]