惠州凹陷HZ25转换带构造特征与成藏条件

The Tectonic Characteristics and Analysis of Hydrocarbon Accumulation Conditions in HZ25 Transfer Zone in Huizhou Sag,Pearl River Mouth Basin

根据最新采集处理的高质量三维地震及3口钻测井分析化验资料,探讨了珠江口盆地惠州凹陷HZ25转换带的构造特征及其对油气成藏的控制作用。精细构造解释、相干体切片及断层位移-距离关系分析表明,HZ25转换带是在NW—SE向拉张作用下形成的同向叠覆的构造转换带,连接F_1断层的下盘和F2断层的上盘,断层总位移量在其内部基本保持不变;构造转换带应力区还伴生形成F_3和F_4断层,并构成复杂的构造-古地貌格局,分割洼陷并控制储集体分布和油气运移方向;构造转换带是盆外隆起水系的入口,为大套粗粒三角洲及优质储层的发育提供了有利地质条件,相对高部位密集发育的断裂系统及三角洲砂体是油气运移和聚集的优良场所,构造变换带与其控制发育的厚层辫状河三角洲耦合,形成地层-岩性复合圈闭。HZ25构造转换带文昌组的油气突破,为惠州凹陷古近系油气勘探打开局面并提供了方向,分布在惠州凹陷边缘的一系列构造转换带是未来值得重视的勘探地区。

The tectonic characteristics of HZ25transfer zone in the Huizhou Sag,Pearl River Mouth Basin,and its controlling effect on hydrocarbon accumulation are discussed in this study.The discussion is based on the latest collected and processed high-quality3D seismic data and the analysis testing data of three drilled wells.The detailed structural interpretation,coherence slices,and analysis of the displacement-distance relationship show that the HZ25transfer zone is a synthetic overlapping transfer zone subject to NW-SE tension.This transfer zone connects the headwall of the F1fault and the hanging wall of the F2fault.Its total interior displacement remained unchanged.The F3and F4faults were formed in association with the stress of the transfer zone areas,and,finally,the complex paleogeomorphology was formed.It splits the sub-sag and controls the distribution of the reservoir body and the direction of hydrocarbon migration.The transfer zone is the entrance to the uplift drainage basin,provides favorable geological conditions for the growth of an extensive set of coarse-grained sedimented deltas,and for a good reservoir.The fracture system and the delta sandstone,with intensive development relative to their high position,are good places for hydrocarbon migration and accumulation.The transfer zone,coupled with its controlled thick-layer braided delta,forms the stratigraphic-lithological trap.The hydrocarbon breakthrough of HZ25transfer zone during the Wenchang Group facilitates hydrocarbon exploration in Huizhou Sag of the Lower Paleogene stratum and points to targets for exploration.In addition,a series of transfer zones distributed on the edge of the Huizhou Sag could be good targets for exploration in the future.