莺-琼盆地成藏条件比较性评价有关问题——与陈斯忠先生商榷

根据对莺 琼盆地成气地质条件的分析认为 :①莺歌海盆地烃源以裂后拗陷期的中新统烃源岩为主 ,晚期泥底辟活动对气藏的破坏作用不严重 ;②钻探证实琼东南盆地Ⅱ号断裂带是烃源断裂 ,能否形成富集高产的富烃气藏 ,主要取决于主运聚输导系统与储盖组合良好的圈闭的有效配置 ;③琼东南盆地上第三系中新统海相泥岩具备一定的生烃能力 ;④琼东南盆地主要成藏组合类型是渐新统自生自储成藏组合的下组合系统和中新统下生上储、自生自储成藏组合的上组合系统 ;⑤莺歌海盆地泥底辟带东方和乐东区 2口深探井的钻探成果证实 ,异常高温高压 (压力系数大于2 0 )地层系统中仍然存在具高突破压力、封盖能力强的泥岩封盖层 ;⑥莺歌海盆地烃源岩时代新、生排烃时间晚 ,有利于天然气运聚动平衡成藏 ,资源量及勘探潜力大 ,应排在中国近海 5个含气盆地 (凹陷 )之首

SOME QUESTIONS ABOUT THE COMPARATIVE EVALUATION OF HYDROCARBON ACCUMULATION CONDITIONS IN YING-QIONG BASINS:A DISCUSSION

The following conclusions are reached based on analyses of geologic gas accumulation conditions in Yinggehai and Qiongdongnan basins. (1) The main source rocks in Yinggehai basin are in Miocene and formed during the post_rift depressing stage, and the destruction of gas reservoirs by the late mud diapiric activity was not serious. (2) Drilling proved that the No.2 Fault in Qiongdongnan basin has brought the source rocks to be faulted, and formation of rich gas reservoirs may depend on an effective match between the main carrier systems and the traps with a good reservoir_seal assemblage. (3) The Miocene marine mudstones in Qiongdongnan basin have some hydrocarbon generation potential. (4) The main petroleum assemblages in Qiongdongnan basin are the lower part of Oligocene self_generating and self_reservoiring assemblage and the upper part of Miocene bottom_generating and top_reservoiring assemblage and self_generating and self_reservoiring assemblage. (5) The drill data from two exploration wells in DF and LD areas in the mud diapir structure belt in Yinggehai basin showed that formations with abnormal high pressure (the pressure coefficient is higher than 2.0) and high temperature still contain the mudstone seals with a good sealing ability and a high breakthrough pressure. (6) Yinggehai basin has abundant hydrocarbon resources and a good exploration potential because of favorable accumulation conditions (younger source rocks and later hydrocarbon expulsion), and therefore should be the best one among the five gas_bearing basins (depressions) offshore China.