琼东南盆地南部隆起带渐新统崖城组层序沉积模式

近期在琼东南盆地南部隆起带前古近系潜山基岩储层和渐新统崖城组砂岩储层中连续获得了天然气勘探重大突破。为了进一步明确崖城组沉积物源及沉积相带展布、为该区天然气勘探部署提供技术支撑，基于最新的钻井资料，结合地震资料解释成果，研究了该盆地南部隆起带崖城组层序地层、沉积物源及层序格架下的沉积相展布。研究结果表明：①南部隆起带崖城组发育3个三级层序，每个三级层序受三级海平面变化控制周期性发育海侵体系域和高位体系域，低位体系域以对老层序高位体系域的改造为主；②崖城组具有多沉积中心与多物源的特点，各凹陷缓坡发育宽相带的扇三角洲—陆棚沉积体系，陡坡发育窄相带的水下扇—陆棚沉积体系；③南部隆起崖城组发育海侵体系域、高位体系域和低位体系域3种层序沉积模式；④南部隆起带前古近系潜山花岗岩基底遭受了长期暴露剥蚀，古隆起形成了重要的潜山型花岗岩储层，崖城组残留了较大面积的扇三角洲砂体，低位期暴露剥蚀改造，形成了具一定规模的砂岩储层。结论认为，该研究成果可以为该区崖城组碎屑岩储层分布规律研究提供依据。

Sequence sedimentary models of Oligocene Yacheng Formation in the southern uplift belt of the Qiongdongnan Basin

In the southern uplift belt of the Qiongdongnan Basin, major breakthroughs in natural gas exploration have been continuously made in the pre-Paleogene buried hill bedrock reservoirs and Oligocene Yacheng Formation sandstone reservoirs in recent years. Therefore, the sequence stratigraphy, sedimentary provenance and sedimentary facies distribution under the sequence framework of the Yacheng Formation in the southern uplift belt are studied based on the latest drilling and seismic data. The study results were achieved as follows. (1) There are three third-order sequences in the Yacheng Formation of the southern uplift belt. Each third-order sequence is controlled by the third-order sea-level change, forming a periodical transgressive system tract and a highstand system tract. The lowstand system tract mainly transforms the highstand system tract of the old sequences. (2) The Yacheng Formation has the characteristics of multiple depocenters and multiple provenances. In each sag, fan delta—continental shelf deposits with wide facies belt are developed on the gentle slope, and subsea fan—continental shelf deposits with narrow facies belt are developed on the steep slope. (3) There are three sequence depositional models in the Yacheng Formation of the southern uplift belt: transgressive system tract, highstand system tract and lowstand system tract. (4) The basement of pre-Paleogene buried hill granite in the southern uplift belt suffered long-term exposure and denudation, and the ancient uplift formed important buried-hill granite reservoir. The Yacheng Formation remains a larger area of fan delta sand bodies that were denuded and reformed during the low stand stage, forming sandstone reservoir with a certain scale. It is concluded that the research results can provide basis for studying the distribution law of clastic reservoirs in the Yacheng Formation in this area.