南海珠江口盆地珠三坳陷油气输导系统研究

Petroleum migration system in Zhu Ⅲ Depression,Pearl River Mouth Basin,South China Sea

通过地震剖面资料解释、伽马测井和声波测井曲线分析,在综合了前人研究成果的基础上,提出了珠江口盆地珠三坳陷的油气输导系统由深大断裂输导体、不整合面输导体和高孔渗海相砂岩输导体联合组成。近EW为主的Ⅱ构造带和珠三南断裂带长期活动为浅部WC9-1,WC9-2和WC19-1油气田与深部烃源岩之间提供了垂向运移通道,包裹体测温结果也显示从深部到浅部温度逐渐降低的垂向运移特征。珠海组和珠江组底部均对应着区域性的不整合,且不整合面之上沉积了海进体系域砂岩,砂岩的孔渗性好,且侧向连续性也好,它们在时空上形成了油气运移的"黄金通道"。地震资料解释在T4和T5构造面上显示出2条明显的NW-SE向构造脊,构造脊之下的断裂—不整合—砂岩的精妙组合构成了文昌B凹陷中WC13-1和WC13-2油田的油气运移输导网络。

Analyses of seismic profile, gamma ray and acoustic loggings have indicated that petroleum migration system in the Zhu Ⅲ Depression of the Pearl River Mouth Basin is composed of deep fault, unconformity and marine sandstone with high porosity and permeability. The EW oriented structural belt Ⅱ and the southern fault remain active for long time, providing pathways for vertical migration in the WC9--1, WC9--2 and WC19--1 oil-and-gas fields. Tests of inclusion show that temperature decreases from the lower to the upper formation, which may prove vertical migration. Regional unconformities have been found at the bottom of Zhuhai and Zhujiang Formations. Sandstones of TST deposit on the unconformities. Due to favorable porosity and permeability as well as lateral connectivity, the sandstones provide excellent pathways for petroleum migration. According to seismic data, there are 2 obvious NW--SE oriented structural ridges on the T4 and T5 structural planes. Fault, unconformity and sandstone under the ridges form highly effective migration system for the WC13--1 and WC13--2 oilfields in the Wenchang B Sag.