莺-琼盆地中新统大型重力流储集体发育条件、沉积特征及天然气勘探有利方向

Development conditions,sedimentary characteristics of Miocene large gravity flow reservoirs and the favorable gas exploration directions in Ying-Qiong basin

重点分析了莺-琼盆地中新统大型重力流储集体发育的必要条件与沉积特征,明确了该区大型储集体发育规律及有利勘探区带。充足的物源供给、区域性相对海平面的大幅下降、适宜的古地貌条件以及频繁的构造运动等因素的有机耦合造就了莺-琼盆地中新统主要发育海底扇和轴向水道这2种大型储集体。中中新统梅山组沉积时期,东方区、乐东-陵水凹陷发育大规模海底扇;晚中新世黄流组沉积时期,东方区和乐东区均发育大型海底扇(群),与此同时琼东南盆地中央峡谷水道体系、莺歌海盆地乐东10-1水道体系亦较发育。钻井揭示,莺-琼盆地中新统大型海底扇和峡谷水道内充填的水道砂储层物性均较好,可以作为良好的储层。圈闭、烃源与运移条件等综合分析认为,莺-琼盆地近海深水区是获得规模储量的成熟区,崖城区是寻找大中型油气藏的现实区,莺歌海凹陷及周边是下步勘探的重要领域。

The necessary conditions and sedimentary characteristics of Miocene large gravity flow reservoirs were analyzed to reveal the development regularity of reservoirs and favorable exploration zone in Yinggehai-Qiongdongnan （Ying- Qiong） basin. In the basin, Miocene large submarine fan and axial channel sandstone reservoirs develop due to suffi- cient sediment supply, significant regional sea level drop, suitable geomorphology and frequent tectonic movements. In Meishan Formation of mid-Miocene, large scale submarine fans deposit in Dongfang area and Ledong-Lingshui sag of Ying-Qiong basin, in Huangliu Formation of late-Miocene, large submarine fans （group） develop in Dongfang and Ledong area. Meanwhile, channel systems such as central canyon in Qiongdongnan basin and the Ledong 10-1 channel in Yinggehai basin also develop. Drilling results indicate good reservoir properties of channel sand bodies in submarine fan and central canyon. Comprehensive analyses of trap, hydrocarbon source and migration conditions show that off- shore deep water area is a mature area to obtain scale exploration reserves, Yacheng is a realistic area to explore large medium reservoirs, and Yinggehai sag and its neighborhood are important targets in future exploration.