石油实验地质2025，Vol.47Issue(6)：1268-1281,14.DOI:10.11781/sysydz2025061268
莺歌海盆地东方1-1底辟不同区域天然气成藏特征与差异富集模式
Accumulation characteristics and differential enrichment modes of natural gas in different regions of Dongfang 1-1 diapir,Yinggehai Basin
摘要
Abstract
As one of the most important gas-bearing structures in the central depression of the Yinggehai Basin,the diapir-associated gas field group has proven geological natural gas reserves of about 180 billion m3.However,the natural gas accumulation characteristics differ significantly across different regions of the diapir,which seriously affects natural gas exploration process in the central depression.Therefore,taking gas reservoirs in different regions(core,affected region,and unaffected region)of the Dongfang 1-1 diapir as research objects,the study employed gas component analysis,carbon isotope analysis,sandstone physical property tests,and inclusion tests to investigate the natural gas composition and source,reservoir characteristics,migration systems,charging stages,and caprock sealing capacity.The results indicated that the natural gas in the second member of the Pliocene Yinggehai Formation(Y2)in the diapiric core and the first member of the Miocene Huangliu Formation(H1)in the unaffected zone was mainly CH4,with an average content of 69.98%.In contrast,CO2 content in the H1 reser-voirs of the affected zone and diapiric core was higher,reaching up to 65.99%.The diapiric core and unaffected zone used diapiric faults and associated micro-fractures,respectively,as the main migration systems.The H1 and Y2 gas reservoirs corresponded to the second and third stages of natural gas charging,respectively.The physical properties of the H1 reservoirs improved progressively from the diapiric core towards the affected and unaffected zones.Both the H1 and Y2 reservoirs showed strong overpressure and overpressure characteristics,with formation pressure coefficients of approximately 1.8 and 1.5,respectively.The overlying mudstone caprock of the H1 reser-voir in the unaffected zone demonstrated strong physical sealing capacity,with a fracture pressure coefficient less than 0.9,followed by the affected zone,and poorest in the diapiric core.Based on these results,three natural gas migration-accumulation modes were established for the different regions of the Dongfang 1-1 diapir:(1)dia-piric core:early hydrocarbon gas charging,late non-hydrocarbon gas charging,overpressure sealing in medium-deep low-permeability reservoirs,and conventional physical sealing in shallow layers;(2)diapir-affected zone:early hydrocarbon gas charging accompanied by mudstone-controlled physical sealing and late non-hydrocarbon gas charging accompanied by overpressure sealing in low-permeability reservoirs;(3)diapir-unaffected zone:hydrocarbon gas charging,micro-fracture migration,and mudstone-controlled physical sealing.关键词
差异富集模式/莺歌海组/黄流组/东方1-1底辟/莺歌海盆地Key words
differential enrichment mode/Yinggehai Formation/Huangliu Formation/Dongfang 1-1 diapir/Yinggehai Basin分类
能源科技引用本文复制引用
杨博,裴健翔,姜福杰,党亚云,彭睿,吴红丽,胡高伟,李卓,何涛..莺歌海盆地东方1-1底辟不同区域天然气成藏特征与差异富集模式[J].石油实验地质,2025,47(6):1268-1281,14.基金项目
中国海洋石油有限公司综合科研项目"莺歌海盆地超压低渗气藏勘探开发关键技术研究"(KJZH-2023-2102)资助. （KJZH-2023-2102）
