湘中坳陷二叠系龙潭组页岩气富集主控因素及勘探潜力  

Main Controlling Factors of Shale Gas Enrichment and Exploration Potential of Permian Longtan Formation in Central Hunan Depression

作　　者：苗凤彬 张国涛[1,2,3] 张保民 王强[1,2,3] 田巍 吕嵘[1,2,3] 周鹏 MIAO Feng-Bin;ZHANG Guo-Tao;ZHANG Bao-Min;WANG Qiang;TIAN Wei;LV Rong;ZHOU Peng(Wuhan Center,China Geological Survey(Geosciences Innovation Center of Central South China),Wuhan 430205,Hubei,China;Technology Innovation Center for Shale Oil and Gas Accumulation Theory and Engineering in Southern Complex Structural Area,China Geological Survey,Wuhan 430205,Hubei,China;Shale Gas Research Center for Southern Complex Structural Area,Wuhan 430205,Hubei,China)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质调查局南方复杂构造区页岩油气成藏理论与工程技术创新中心,湖北武汉430205 [3]南方复杂构造区页岩气研究中心,湖北武汉430205

出　　处：《华南地质》2025年第1期109-125,共17页South China Geology

基　　金：中国地质调查局地质调查项目(DD20243464、DD20240047)。

摘　　要：湘中坳陷是南方复杂构造带页岩气调查评价新区,龙潭组海陆过渡相页岩是重点勘探层位之一。综合野外剖面调查、钻探及实验测试数据,本文取得了以下认识:(1)区内龙潭组页岩厚度呈现南厚北薄、中部厚东西部薄的变化趋势,优质页岩主要形成于潟湖沉积相区,厚度为60~130 m,以Ⅱ型有机质为主,TOC大于1.5%,1.5%<R_(o)<3.0%,具备较好的生烃物质基础;页岩中石英等脆性矿物含量较大,具高硅低钙特点,储集空间类型丰富,平均孔隙度为3.3%,渗透率为0.0081 mD,具低孔低渗、高脆性储层特征。(2)龙潭组含气性整体呈现出南部邵阳凹陷高、北部涟源凹陷低的区域性分布规律与中部高、上下部低的纵向变化特征。(3)潟湖相还原环境形成较大厚度的富有机质页岩具有优质的生烃基础与自身封盖性,是富集成藏的基础;保存条件控制含气量,是富集成藏的重要保证,形成了龙潭组“沉积相控藏、保存条件定富”的残留向斜型页岩气成藏模式。(4)龙潭组页岩气有利区分布分散,共优选出邓家铺-滩头、三比田-箍脚底、短陂桥-牛马司、桥头河-洪山殿4个龙潭组页岩气有利片区,主体位于邵阳凹陷内的向斜中心区,测算资源量为1446.9×10^(8)m^(3),表明湘中坳陷龙潭组具备一定的页岩气资源潜力。The central Hunan depression is an emerging area for shale gas investigation and evaluation within the complex structural belt of southern China.The marine-continental transitional shale in the Longtan Formation in this area is a key exploration target.Based on field profile surveys,drilling measurements,and experimental testing data,The following insights have been obtained:(1)The thickness of the Longtan Formation shale exhibits a spatial trend,being thicker in the south and thinner in the north,as well as thicker in the central area and thinner in the eastern and western areas.High-quality shale is predominantly developed in the lagoon sedimentary facies zone,with a thickness ranging from 60 to-130 metres.This shale primarily composes type Ⅱ organic matter,with TOC content exceeding 1.5%,and the R_(o) between 1.5%and 3.0%,indicating a robust foundation for hydrocarbon generation.The shale is rich in brittle minerals such as quartz,characterized by high silicon and low calcium content.The shale reservoirs feature diverse pore types,with an average porosity of 3.3%and an average permeability of 0.0081 mD,demonstrating low porosity,low permeability,and high brittleness.(2)The overall gas content of the Longtan Formation displays a regional distribution pattern,with higher values in the southern Shaoyang sag and lower values in the northern Lianyuan sag.Vertically,the gas content is higher in the central section and lower in the upper and lower parts.(3)The thick organic-rich shale formed in the reducing environment of the lagoon facies possesses a high-quality hydrocarbon generation foundation and self-sealing capacity,,serving as the basis for shale gas enrichment and accumulation.The preservation conditions are critical in controlling the gas content and are essential for shale gas enrichment.A shale gas accumulation model for the Longtan Formation has been established,emphasizing that‘sedimentary facies control the formation of gas reservoirs,while preservation conditions determine gas enrichment’.The sy

关 键 词：成藏地质特征 富集主控因素 资源潜力 页岩气 龙潭组 湘中坳陷 

分 类 号：P618.13[天文地球—矿床学]