南海北部油气成藏区带的划分与勘探前景

Plays division and exploration potentials in the northern South China Sea

南海北部大陆边缘整体勘探程度较低。为加强该区油气成藏特征的系统分析与对比,根据构造、沉积特征的差异性,将该区划分为4个油气成藏区带:走滑拉分区(莺歌海盆地)、陆内裂陷区(北部湾盆地)、陆架浅水区(琼东南盆地北部裂陷带,珠江口盆地北部裂陷带的珠一、珠三坳陷)、陆坡深水区(珠江口盆地珠二坳陷,琼东南盆地中央裂陷带及南部裂陷带)。进而分析了各区带的油气成藏特征及勘探前景,结论认为:①走滑拉分区油气成藏主要受控于泥底辟构造活动,应重点突破下含油气系统;②陆内裂陷区断裂构造发育,企西隆起东部是寻找大中型油田的有利区带;③陆架浅水区"皮薄肉厚",油气勘探应以古近系陆相断陷沉积的储盖组合类型为主;④陆坡深水区油气成藏要素配置良好,是未来发现大型油气田、开创油气勘探新局面的主战场。

Exploration maturity is relatively low in the continental margin of the northern South China Sea.In order to strengthen systematic analysis and correlation of hydrocarbon pooling characteristics in the study area,we identify four plays according to the structural and sedimentary features,including a strike-slip pull-apart play(the Yinggehai Basin),an intra-continental faulted depression play(the Beibuwan Basin),a shallow-water shelf play(the northern faulted depression in the Qiongdongnan Basin,the Zhu-1 and Zhu-3 depressions in the northern faulted depression of the Pearl River Mouth Basin),and a deep-water slope play(the Zhu-2 depression in the Pearl River Mouth Basin,the central and southern faulted depressions in the Qiongdongnan Basin).The hydrocarbon pooling features and exploration potentials of each play are analyzed respectively.The strike-slip pull-apart play is mainly controlled by mud diapir structures,thus the lower petroleum system should be the major target.The intra-continental faulted depression play is intensively faulted and the eastern part of the Qixi uplift is favorable for the formation of large-and medium-oil reservoirs.Exploration in the shallow-water shelf play should focus on reservoir-seal combinations of the Palaeogene in the continental faulted depression.The deep-water slope play has favorable combinations of hydrocarbon pooling elements,thus it will be the major area to find large oil and gas fields in the future.