珠江口盆地隆起区残留洼陷地质特征与石油勘探新领域

Geological characteristics of residual sags and a new field of petroleum exploration in the uplift area of Pearl River Mouth Basin

珠江口盆地近年来勘探实践证实,储量增长主要依靠富生烃凹陷的新突破,找到发育文昌组半深湖—深湖相优质烃源岩的潜在富生烃凹陷成为该盆地增储上产的关键,因此中央隆起带残留洼陷作为石油勘探新区逐渐引起广大学者的关注。珠江口盆地中央隆起带存在19个文昌组残留洼陷,并利用"三步定洼法"系统确定残洼文昌组分布规模与结构特征,初步认为残洼具有较好的勘探潜力;通过对已证实富生烃凹陷的类比分析,运用"无井区烃源岩评价法",指出如隆起区残洼控洼断裂活动速率大于100 m/Ma,沉降速率大于200 m/Ma,地震剖面上具有低频连续强反射特征,则残洼文昌组发育半深湖—深湖相优质烃源岩。首次提出珠江口盆地中央隆起区残留洼陷具有较大的勘探前景,对拓展新区勘探具有重要的战略意义。

In recent years, exploration practices in Pearl River Mouth Basin （PRMB） have proven that the growth of petroleum re serves mainly depends on new discoveries of hydrocarbon-rich sags. Thus, finding potential hydrocarbon rich sags with deep and semi-deep lacustrine source rocks of Wenchang Formation has become a key step for increasing petroleum reserves and production in PRMB. As a new field for petroleum exploration, the central uplift belt of PRMB has attracted increasing attention of relevant re searchers. Here we propose the discovery of Wenchang Formation in 19 residual sags in the central uplift belt of PRMB. The distribution and structural characteristics of the Wenchang Formation in these residual sags were determined using a three-step method. A comparative analysis was performed on the proven hydrocarbon-rich sags by source rock evaluation in non well area. Results show that the residual sags have great potential for petroleum exploration. With boundary fault activity rate greater than 100 m/Ma, the subsiding rate is greater than 200 m/Ma. High amplitude and continuous low frequency reflection in the seismic profile imply the de- velopment of deep/semi-deep lacustrine source rocks in the residual sags of Wenchang Formation. This study presents the first evi- dence that residual sags in the central uplift belt has great potential for petroleum exploration, which has strategic implications for expanding new fields of petroleum exploration in PRMB.