南海北部琼东南盆地深水区陵水凹陷南部油气成藏条件

勘探已证实陵水凹陷浅层新近系发育中央峡谷莺歌海组—黄流组有效天然气成藏组合。渐新统崖城组煤系是陵水凹陷的主力气源岩,也可为陵水凹陷南部提供烃源。渐新统上部陵水组一段—中新统下部三亚组二段发育扇三角洲、浊积水道、海底扇砂岩储层,砂体富集的主控因素是凹陷边界断裂转换带、断阶带及构造坡折。陵水凹陷南部具有晚期成藏的特点,陵水凹陷生成的烃类通过断裂、砂体向南侧发生垂向与侧向运聚。综合储层、运移及圈闭条件等因素,优选出陵南斜坡反向断阶构造带为有利勘探区带。

Conditions of Hydrocarbon Accumulation in the South of Deepwater Lingshui Sag and Adjacent Area,Qiongdongnan Basin,South China Sea

It is proved that a shallow Neogene Huangliu-Yinggehai gas play is developed in the central canyon in Lingshui Sag and its adjacent area in Qiongdongnan Basin. The deep Oligocene Yacheng coal series is the major matured source rock in the sag, which provides abundant hydrocarbon to the south part of the sag. Fan delta, turbidite channel and submarine fan facies sandstone reservoirs are developed in the Upper Oligocene Lingshui 1st Member Formation and the Lower Miocene Sanya 2nd Member. Main controlling factors of sand body enrichment are contributed to the boundary fault transfer belt, faulted terrace belt and structural slope-break belts. Hydrocarbon accumulation pattern is described as getting close to source rock, migrating in vertical and lateral directions and gathering in the later period. On account of the conditions including reservoir, migration and traps, it is optimized that the reverse faulted terrace belt in the slope of southern Lingshui sag is the areas favorable for exploration.