珠江口盆地恩平凹陷北部披覆带油气成藏条件

Hydrocarbon accumulation conditions in drape structure zone north of Enping sag,Pearl River Mouth Basin

珠江口盆地北部隆起带的油气勘探始于20世纪70年代,直到2015年依然未获商业突破。此后勘探研究人员创新提出一系列地质认识:低角度断层控制的恩平17洼具备向北部陡坡带大规模供烃的烃源条件;陡坡带大型弧形断层形成的“陡坡扇体+断层”高效输导体系能够向北部披覆带中浅层大规模输导油气;先存基底隆起背景下继承性发育的断裂构造是油气运聚的有利区;大型海相三角洲砂岩与海泛泥岩组合提供了良好的储盖条件。基于这些认识,推动钻探并在恩平凹陷北部披覆带发现了珠江口盆地北部隆起带的第一个商业油田。恩平凹陷北部披覆带的油藏均为典型的构造油藏,为常温常压系统;储层类型为中高孔、中高渗的砂岩储层,经济效益良好。

Oil and gas exploration in the northern uplift zone of Pearl River Mouth Basin began in the 1970s,and there was no commercial breakthrough until 2015.Since then,experts and scholars have creatively put forward a series of geological viewpoints the Enping 17 subsag controlled by low angle fault has the hydrocarbon source conditions for large-scale hydrocarbon supply to the northern steep slope zone;The“steep slope fan+fault”efficient channeling system formed by large arcuate fault in the steep slope zone may channel oil and gas to the middle and shallow layers of the drape zone in the north on a large scale;The inherited fault structure under the backdrop of pre-existing basement uplift is a favorable area for oil and gas migration and accumulation;The combination of large marine delta sandstone and marine flooding mudstone provides a good reservoir-cap condition.Based on these understandings,drilling activities are advanced in the drape structure zone north of Enping sag,and the first commercial oilfield is discovered in the northern uplift zone of Pearl River Mouth Basin.The reservoirs in the drape structure zone north of Enping sag are typical structure ones,which are normal temperature and pressure system;The reservoir type is the medium-high porosity and medium-high permeability sandstone reservoir with good economic development condition.